fix(alerting): Resolve issue with blank GoogleChat messages (#364)

* debug: Print GoogleChat request body

* chore: Update TwiN/whois to v1.1.0

* fix: Add missing client changes

* test: Improve DNS tests

* chore: Remove accidental change

* docs: Add note for future change to default behavior

* fix(alerting): Don't include URL in Google Chat alert if endpoint type isn't HTTP

Fixes #362

.dockerignore

@@ -1,5 +1,7 @@
-example
+.examples
 Dockerfile
 .github
 .idea
 .git
+web/app
+*.db

.examples/docker-compose-grafana-prometheus/README.md

@@ -0,0 +1,41 @@
+## Usage
+Gatus exposes Prometheus metrics at `/metrics` if the `metrics` configuration option is set to `true`.
+
+To run this example, all you need to do is execute the following command:
+```console
+docker-compose up
+```
+Once you've done the above, you should be able to access the Grafana dashboard at `http://localhost:3000`.
+
+![Gatus Grafana dashboard](../../.github/assets/grafana-dashboard.png)
+
+
+## Queries
+By default, this example has a Grafana dashboard with some panels, but for the sake of verbosity, you'll find
+a list of simple queries below. Those make use of the `key` parameter, which is a concatenation of the endpoint's
+group and name.
+
+### Success rate
+```
+sum(rate(gatus_results_total{success="true"}[30s])) by (key) / sum(rate(gatus_results_total[30s])) by (key)
+```
+
+### Response time
+```
+gatus_results_duration_seconds
+```
+
+### Total results per minute
+```
+sum(rate(gatus_results_total[5m])*60) by (key)
+```
+
+### Total successful results per minute
+```
+sum(rate(gatus_results_total{success="true"}[5m])*60) by (key)
+```
+
+### Total unsuccessful results per minute
+```
+sum(rate(gatus_results_total{success="false"}[5m])*60) by (key)
+```

.examples/docker-compose-grafana-prometheus/config/config.yaml

@@ -0,0 +1,19 @@
+metrics: true
+endpoints:
+  - name: website
+    url: https://twin.sh/health
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+
+  - name: example
+    url: https://example.com/
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+
+  - name: github
+    url: https://api.github.com/healthz
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"

.examples/docker-compose-grafana-prometheus/docker-compose.yml

@@ -0,0 +1,42 @@
+version: "3.9"
+services:
+  gatus:
+    container_name: gatus
+    image: twinproduction/gatus
+    restart: always
+    ports:
+      - "8080:8080"
+    volumes:
+      - ./config:/config
+    networks:
+      - metrics
+
+  prometheus:
+    container_name: prometheus
+    image: prom/prometheus:v2.14.0
+    restart: always
+    command: --config.file=/etc/prometheus/prometheus.yml
+    ports:
+      - "9090:9090"
+    volumes:
+      - ./prometheus/prometheus.yml:/etc/prometheus/prometheus.yml
+    networks:
+      - metrics
+
+  grafana:
+    container_name: grafana
+    image: grafana/grafana:6.4.4
+    restart: always
+    environment:
+      GF_SECURITY_ADMIN_PASSWORD: secret
+    ports:
+      - "3000:3000"
+    volumes:
+      - ./grafana/grafana.ini/:/etc/grafana/grafana.ini:ro
+      - ./grafana/provisioning/:/etc/grafana/provisioning/:ro
+    networks:
+      - metrics
+
+networks:
+  metrics:
+    driver: bridge

.examples/docker-compose-grafana-prometheus/grafana/provisioning/dashboards/gatus.json

@@ -0,0 +1,582 @@
+{
+  "annotations": {
+    "list": [
+      {
+        "builtIn": 1,
+        "datasource": "-- Grafana --",
+        "enable": true,
+        "hide": true,
+        "iconColor": "rgba(0, 211, 255, 1)",
+        "name": "Annotations & Alerts",
+        "type": "dashboard"
+      }
+    ]
+  },
+  "editable": true,
+  "gnetId": null,
+  "graphTooltip": 0,
+  "id": 3,
+  "links": [],
+  "panels": [
+    {
+      "cacheTimeout": null,
+      "datasource": null,
+      "description": "Number of successful results compared to the total number of results during the current interval",
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 0
+      },
+      "id": 9,
+      "links": [],
+      "options": {
+        "fieldOptions": {
+          "calcs": [
+            "mean"
+          ],
+          "defaults": {
+            "mappings": [
+              {
+                "id": 0,
+                "op": "=",
+                "text": "N/A",
+                "type": 1,
+                "value": "null"
+              }
+            ],
+            "max": 1,
+            "min": 0,
+            "nullValueMode": "connected",
+            "thresholds": [
+              {
+                "color": "red",
+                "value": null
+              },
+              {
+                "color": "semi-dark-orange",
+                "value": 0.6
+              },
+              {
+                "color": "yellow",
+                "value": 0.8
+              },
+              {
+                "color": "dark-green",
+                "value": 0.95
+              }
+            ],
+            "unit": "percentunit"
+          },
+          "override": {},
+          "values": false
+        },
+        "orientation": "horizontal",
+        "showThresholdLabels": false,
+        "showThresholdMarkers": false
+      },
+      "pluginVersion": "6.4.4",
+      "targets": [
+        {
+          "expr": "sum(rate(gatus_results_total{success=\"true\"}[30s])) by (key) / sum(rate(gatus_results_total[30s])) by (key)",
+          "hide": false,
+          "legendFormat": "{{key}}",
+          "refId": "B"
+        }
+      ],
+      "timeFrom": null,
+      "timeShift": null,
+      "title": "Success rate",
+      "type": "gauge"
+    },
+    {
+      "aliasColors": {},
+      "bars": false,
+      "cacheTimeout": null,
+      "dashLength": 10,
+      "dashes": false,
+      "datasource": null,
+      "fill": 1,
+      "fillGradient": 0,
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 0
+      },
+      "id": 11,
+      "legend": {
+        "avg": false,
+        "current": false,
+        "max": false,
+        "min": false,
+        "show": true,
+        "total": false,
+        "values": false
+      },
+      "lines": true,
+      "linewidth": 1,
+      "links": [],
+      "nullPointMode": "null as zero",
+      "options": {
+        "dataLinks": []
+      },
+      "percentage": false,
+      "pluginVersion": "6.4.4",
+      "pointradius": 2,
+      "points": false,
+      "renderer": "flot",
+      "seriesOverrides": [],
+      "spaceLength": 10,
+      "stack": false,
+      "steppedLine": false,
+      "targets": [
+        {
+          "expr": "gatus_results_duration_seconds",
+          "format": "time_series",
+          "instant": false,
+          "interval": "",
+          "intervalFactor": 1,
+          "legendFormat": "{{key}}",
+          "refId": "A"
+        }
+      ],
+      "thresholds": [],
+      "timeFrom": null,
+      "timeRegions": [],
+      "timeShift": null,
+      "title": "Response time",
+      "tooltip": {
+        "shared": true,
+        "sort": 0,
+        "value_type": "individual"
+      },
+      "type": "graph",
+      "xaxis": {
+        "buckets": null,
+        "mode": "time",
+        "name": null,
+        "show": true,
+        "values": []
+      },
+      "yaxes": [
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        },
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        }
+      ],
+      "yaxis": {
+        "align": false,
+        "alignLevel": null
+      }
+    },
+    {
+      "aliasColors": {},
+      "bars": false,
+      "cacheTimeout": null,
+      "dashLength": 10,
+      "dashes": false,
+      "datasource": null,
+      "fill": 1,
+      "fillGradient": 0,
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 0,
+        "y": 8
+      },
+      "id": 10,
+      "legend": {
+        "avg": false,
+        "current": false,
+        "max": false,
+        "min": false,
+        "show": true,
+        "total": false,
+        "values": false
+      },
+      "lines": true,
+      "linewidth": 1,
+      "links": [],
+      "nullPointMode": "connected",
+      "options": {
+        "dataLinks": []
+      },
+      "percentage": false,
+      "pluginVersion": "6.4.4",
+      "pointradius": 2,
+      "points": true,
+      "renderer": "flot",
+      "seriesOverrides": [],
+      "spaceLength": 10,
+      "stack": false,
+      "steppedLine": false,
+      "targets": [
+        {
+          "expr": "sum(rate(gatus_results_total{success=\"true\"}[30s])) by (key) / sum(rate(gatus_results_total[30s])) by (key)",
+          "format": "time_series",
+          "instant": false,
+          "interval": "",
+          "intervalFactor": 1,
+          "legendFormat": "{{key}}",
+          "refId": "A"
+        }
+      ],
+      "thresholds": [],
+      "timeFrom": null,
+      "timeRegions": [],
+      "timeShift": null,
+      "title": "Success rate",
+      "tooltip": {
+        "shared": true,
+        "sort": 0,
+        "value_type": "individual"
+      },
+      "type": "graph",
+      "xaxis": {
+        "buckets": null,
+        "mode": "time",
+        "name": null,
+        "show": true,
+        "values": []
+      },
+      "yaxes": [
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        },
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        }
+      ],
+      "yaxis": {
+        "align": false,
+        "alignLevel": null
+      }
+    },
+    {
+      "aliasColors": {},
+      "bars": false,
+      "dashLength": 10,
+      "dashes": false,
+      "datasource": null,
+      "description": "Number of results per minute",
+      "fill": 1,
+      "fillGradient": 0,
+      "gridPos": {
+        "h": 8,
+        "w": 12,
+        "x": 12,
+        "y": 8
+      },
+      "id": 2,
+      "interval": "",
+      "legend": {
+        "alignAsTable": false,
+        "avg": false,
+        "current": false,
+        "hideEmpty": false,
+        "hideZero": false,
+        "max": false,
+        "min": false,
+        "rightSide": false,
+        "show": true,
+        "total": false,
+        "values": false
+      },
+      "lines": true,
+      "linewidth": 1,
+      "nullPointMode": "null",
+      "options": {
+        "dataLinks": []
+      },
+      "percentage": false,
+      "pointradius": 2,
+      "points": false,
+      "renderer": "flot",
+      "seriesOverrides": [],
+      "spaceLength": 10,
+      "stack": false,
+      "steppedLine": false,
+      "targets": [
+        {
+          "expr": "sum(rate(gatus_results_total[5m])*60) by (key)",
+          "format": "time_series",
+          "hide": false,
+          "instant": false,
+          "interval": "30s",
+          "intervalFactor": 1,
+          "legendFormat": "{{key}}",
+          "refId": "A"
+        }
+      ],
+      "thresholds": [],
+      "timeFrom": null,
+      "timeRegions": [],
+      "timeShift": null,
+      "title": "Total results per minute",
+      "tooltip": {
+        "shared": true,
+        "sort": 0,
+        "value_type": "individual"
+      },
+      "type": "graph",
+      "xaxis": {
+        "buckets": null,
+        "mode": "time",
+        "name": null,
+        "show": true,
+        "values": []
+      },
+      "yaxes": [
+        {
+          "decimals": null,
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        },
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        }
+      ],
+      "yaxis": {
+        "align": false,
+        "alignLevel": null
+      }
+    },
+    {
+      "aliasColors": {},
+      "bars": false,
+      "dashLength": 10,
+      "dashes": false,
+      "datasource": null,
+      "fill": 1,
+      "fillGradient": 0,
+      "gridPos": {
+        "h": 7,
+        "w": 12,
+        "x": 0,
+        "y": 16
+      },
+      "id": 5,
+      "legend": {
+        "avg": false,
+        "current": false,
+        "max": false,
+        "min": false,
+        "show": true,
+        "total": false,
+        "values": false
+      },
+      "lines": true,
+      "linewidth": 1,
+      "nullPointMode": "null",
+      "options": {
+        "dataLinks": []
+      },
+      "percentage": false,
+      "pointradius": 2,
+      "points": false,
+      "renderer": "flot",
+      "seriesOverrides": [],
+      "spaceLength": 10,
+      "stack": false,
+      "steppedLine": false,
+      "targets": [
+        {
+          "expr": "sum(rate(gatus_results_total{success=\"true\"}[5m])*60) by (key)",
+          "instant": false,
+          "interval": "30s",
+          "legendFormat": "{{key}}",
+          "refId": "A"
+        }
+      ],
+      "thresholds": [],
+      "timeFrom": null,
+      "timeRegions": [],
+      "timeShift": null,
+      "title": "Successful results per minute",
+      "tooltip": {
+        "shared": true,
+        "sort": 0,
+        "value_type": "individual"
+      },
+      "type": "graph",
+      "xaxis": {
+        "buckets": null,
+        "mode": "time",
+        "name": null,
+        "show": true,
+        "values": []
+      },
+      "yaxes": [
+        {
+          "decimals": null,
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        },
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        }
+      ],
+      "yaxis": {
+        "align": false,
+        "alignLevel": null
+      }
+    },
+    {
+      "aliasColors": {},
+      "bars": false,
+      "dashLength": 10,
+      "dashes": false,
+      "datasource": null,
+      "fill": 1,
+      "fillGradient": 0,
+      "gridPos": {
+        "h": 7,
+        "w": 12,
+        "x": 12,
+        "y": 16
+      },
+      "id": 3,
+      "legend": {
+        "avg": false,
+        "current": false,
+        "max": false,
+        "min": false,
+        "show": true,
+        "total": false,
+        "values": false
+      },
+      "lines": true,
+      "linewidth": 1,
+      "nullPointMode": "null",
+      "options": {
+        "dataLinks": []
+      },
+      "percentage": false,
+      "pointradius": 2,
+      "points": false,
+      "renderer": "flot",
+      "seriesOverrides": [],
+      "spaceLength": 10,
+      "stack": false,
+      "steppedLine": false,
+      "targets": [
+        {
+          "expr": "sum(rate(gatus_results_total{success=\"false\"}[5m])*60) by (key)",
+          "interval": "30s",
+          "legendFormat": "{{key}} ",
+          "refId": "A"
+        }
+      ],
+      "thresholds": [],
+      "timeFrom": null,
+      "timeRegions": [],
+      "timeShift": null,
+      "title": "Unsuccessful results per minute",
+      "tooltip": {
+        "shared": true,
+        "sort": 0,
+        "value_type": "individual"
+      },
+      "type": "graph",
+      "xaxis": {
+        "buckets": null,
+        "mode": "time",
+        "name": null,
+        "show": true,
+        "values": []
+      },
+      "yaxes": [
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        },
+        {
+          "format": "short",
+          "label": null,
+          "logBase": 1,
+          "max": null,
+          "min": null,
+          "show": true
+        }
+      ],
+      "yaxis": {
+        "align": false,
+        "alignLevel": null
+      }
+    }
+  ],
+  "refresh": "1m",
+  "schemaVersion": 20,
+  "style": "dark",
+  "tags": [],
+  "templating": {
+    "list": []
+  },
+  "time": {
+    "from": "now-1h",
+    "to": "now"
+  },
+  "timepicker": {
+    "refresh_intervals": [
+      "5s",
+      "10s",
+      "30s",
+      "1m",
+      "5m",
+      "15m",
+      "30m",
+      "1h",
+      "2h",
+      "1d"
+    ]
+  },
+  "timezone": "",
+  "title": "Gatus",
+  "uid": "KPI7Qj1Wk",
+  "version": 2
+}

.examples/docker-compose-mattermost/config/config.yaml

@@ -0,0 +1,16 @@
+alerting:
+  mattermost:
+    webhook-url: "http://mattermost:8065/hooks/tokengoeshere"
+    insecure: true
+
+endpoints:
+  - name: example
+    url: https://example.org
+    interval: 1m
+    alerts:
+      - type: mattermost
+        enabled: true
+        description: "health check failed 3 times in a row"
+        send-on-resolved: true
+    conditions:
+      - "[STATUS] == 200"

.examples/docker-compose-mattermost/docker-compose.yml

@@ -0,0 +1,23 @@
+version: "3.9"
+services:
+  gatus:
+    container_name: gatus
+    image: twinproduction/gatus:latest
+    ports:
+      - "8080:8080"
+    volumes:
+      - ./config:/config
+    networks:
+      - default
+
+  mattermost:
+    container_name: mattermost
+    image: mattermost/mattermost-preview:5.26.0
+    ports:
+      - "8065:8065"
+    networks:
+      - default
+
+networks:
+  default:
+    driver: bridge

.examples/docker-compose-postgres-storage/config/config.yaml

@@ -0,0 +1,42 @@
+storage:
+  type: postgres
+  path: "postgres://username:password@postgres:5432/gatus?sslmode=disable"
+
+endpoints:
+  - name: back-end
+    group: core
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+      - "[CERTIFICATE_EXPIRATION] > 48h"
+
+  - name: monitoring
+    group: internal
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+
+  - name: nas
+    group: internal
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+
+  - name: example-dns-query
+    url: "8.8.8.8" # Address of the DNS server to use
+    interval: 5m
+    dns:
+      query-name: "example.com"
+      query-type: "A"
+    conditions:
+      - "[BODY] == 93.184.216.34"
+      - "[DNS_RCODE] == NOERROR"
+
+  - name: icmp-ping
+    url: "icmp://example.org"
+    interval: 1m
+    conditions:
+      - "[CONNECTED] == true"

.examples/docker-compose-postgres-storage/docker-compose.yml

@@ -0,0 +1,29 @@
+version: "3.9"
+services:
+  postgres:
+    image: postgres
+    volumes:
+      - ./data/db:/var/lib/postgresql/data
+    ports:
+      - "5432:5432"
+    environment:
+      - POSTGRES_DB=gatus
+      - POSTGRES_USER=username
+      - POSTGRES_PASSWORD=password
+    networks:
+      - web
+
+  gatus:
+    image: twinproduction/gatus:latest
+    restart: always
+    ports:
+      - "8080:8080"
+    volumes:
+      - ./config:/config
+    networks:
+      - web
+    depends_on:
+      - postgres
+
+networks:
+  web:

.examples/docker-compose-sqlite-storage/config/config.yaml

@@ -0,0 +1,42 @@
+storage:
+  type: sqlite
+  path: /data/data.db
+
+endpoints:
+  - name: back-end
+    group: core
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+      - "[CERTIFICATE_EXPIRATION] > 48h"
+
+  - name: monitoring
+    group: internal
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+
+  - name: nas
+    group: internal
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+
+  - name: example-dns-query
+    url: "8.8.8.8" # Address of the DNS server to use
+    interval: 5m
+    dns:
+      query-name: "example.com"
+      query-type: "A"
+    conditions:
+      - "[BODY] == 93.184.216.34"
+      - "[DNS_RCODE] == NOERROR"
+
+  - name: icmp-ping
+    url: "icmp://example.org"
+    interval: 1m
+    conditions:
+      - "[CONNECTED] == true"

.examples/docker-compose-sqlite-storage/docker-compose.yml

@@ -0,0 +1,9 @@
+version: "3.9"
+services:
+  gatus:
+    image: twinproduction/gatus:latest
+    ports:
+      - "8080:8080"
+    volumes:
+      - ./config:/config
+      - ./data:/data/

.examples/docker-compose/config/config.yaml

@@ -0,0 +1,6 @@
+endpoints:
+  - name: example
+    url: https://example.org
+    interval: 30s
+    conditions:
+      - "[STATUS] == 200"

.examples/docker-compose/docker-compose.yml

@@ -0,0 +1,8 @@
+version: "3.8"
+services:
+  gatus:
+    image: twinproduction/gatus:latest
+    ports:
+      - 8080:8080
+    volumes:
+      - ./config:/config

.examples/docker-minimal/config.yaml

@@ -0,0 +1,6 @@
+endpoints:
+  - name: example
+    url: https://example.org
+    interval: 30s
+    conditions:
+      - "[STATUS] == 200"

.examples/kubernetes/gatus.yaml

@@ -0,0 +1,115 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: gatus
+  namespace: kube-system
+data:
+  config.yaml: |
+    metrics: true
+    endpoints:
+      - name: website
+        url: https://twin.sh/health
+        interval: 5m
+        conditions:
+          - "[STATUS] == 200"
+          - "[BODY].status == UP"
+
+      - name: github
+        url: https://api.github.com/healthz
+        interval: 5m
+        conditions:
+          - "[STATUS] == 200"
+
+      - name: cat-fact
+        url: "https://cat-fact.herokuapp.com/facts/random"
+        interval: 5m
+        conditions:
+          - "[STATUS] == 200"
+          - "[BODY].deleted == false"
+          - "len([BODY].text) > 0"
+          - "[BODY].text == pat(*cat*)"
+          - "[STATUS] == pat(2*)"
+          - "[CONNECTED] == true"
+
+      - name: example
+        url: https://example.com/
+        conditions:
+          - "[STATUS] == 200"
+---
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: gatus
+  namespace: kube-system
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: gatus
+  namespace: kube-system
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: gatus
+  template:
+    metadata:
+      name: gatus
+      namespace: kube-system
+      labels:
+        app: gatus
+    spec:
+      serviceAccountName: gatus
+      terminationGracePeriodSeconds: 5
+      containers:
+        - image: twinproduction/gatus
+          imagePullPolicy: IfNotPresent
+          name: gatus
+          ports:
+            - containerPort: 8080
+              name: http
+              protocol: TCP
+          resources:
+            limits:
+              cpu: 250m
+              memory: 100M
+            requests:
+              cpu: 50m
+              memory: 30M
+          readinessProbe:
+            httpGet:
+              path: /health
+              port: 8080
+            initialDelaySeconds: 5
+            periodSeconds: 10
+            successThreshold: 1
+            failureThreshold: 3
+          livenessProbe:
+            httpGet:
+              path: /health
+              port: 8080
+            initialDelaySeconds: 10
+            periodSeconds: 10
+            successThreshold: 1
+            failureThreshold: 5
+          volumeMounts:
+            - mountPath: /config
+              name: gatus-config
+      volumes:
+        - configMap:
+            name: gatus
+          name: gatus-config
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: gatus
+  namespace: kube-system
+spec:
+  ports:
+    - name: http
+      port: 8080
+      protocol: TCP
+      targetPort: 8080
+  selector:
+    app: gatus

.gitattributes

@@ -1 +1 @@
-* text=lf
+* text=auto eol=lf

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: [TwiN]

.github/assets/gatus-diagram.drawio

@@ -0,0 +1 @@
+<mxfile host="app.diagrams.net" modified="2021-09-12T22:49:28.336Z" agent="5.0 (Windows)" etag="r9FJ6Bphqwq-LaTO-jp3" version="15.0.6" type="device"><diagram id="FBbfVOMCjf6Z2LK8Yagy" name="Page-1">7Vtdb5swFP01edwEOCHJY5t03aR1q9RWbR9d8MCb4TJj8rFfP9OYBOI2YVrTi5S8RPjaxOack2sf7PTIJFlcSprFVxAy0fOccNEj057nDceu/iwDy1WADEarQCR5uAq5m8AN/8NM0DHRgocsbzRUAELxrBkMIE1ZoBoxKiXMm81+gGj2mtGIWYGbgAo7es9DFZuo5zibis+MR3HV9dgzNQmtWptAHtMQ5rUQueiRiQRQq6tkMWGiBK8CZnXfp1dq1yOTLFVtbvj2/UGwZFq4GpXZfXYJ8Yh9MN8yo6IwT2wGq5YVBCzUiJgiSBVDBCkVF5vouYQiDVnZjaNLmzZfATIddHXwJ1NqaeilhQIdilUiTO2qz7KjV5/NhHIoZMB2PJAZv6IyYmrXgw/XFGjtMkiYkkt9o2SCKj5rDoQaFUXrdhuc9YWB+h9g9yzYteKk4mlkwb8Bt0RqHnPFbjL6jMFc/+ReAnKmv4otdkNpP7m5YTQ2ejW/WM8xg5039L+KxTXp+86BwCIYktRoyeWDuf+58FgWPg6q4nRRr5wuTekNpey3lPIIU8n9Ezk7yfEwyRngkrPh47Fe1x1yiIPJjm9NAnOqgjgE/Elg6DYnAUKwJ4HhkeaZUds842NKeWRJOVcgy7U1tpK3lzN9H1vJYwurI5W2O2yrbdQ0XaXCEz+vNhyj8uOe+NnDD6pDcE/5bV9+e2UKeyd+jtVft+eHoPJzrBa7PT+oJttFdtnd54fg5jf/xM8efnB/P2aYNUOUSZjxkEmLuD1+sWkue//vHl1n2LW34a7tta9Ynmuv/cRliI8Y2Xp15A5H7RDzDoaY7bhvBA1+dQ8rj2BjVX1xDatrLS05LdSyg3g56Hi9tIHqC93techn+jIqL28ZTfIqrvupVXUQVB8dVM9OcVQpJhPIVfcAc/tjbMCIBdgtEyySNOkeXN4YXV/H6qi81ruWuKcjjtVRtecHd8//WN+It+aHoL4R9+yd5XI7Dn8zzrJT+Ltxnu0+899CA9G9ibM/agnW4SZO23vyNGEJyA6ag/7AwYZrjJsnm+dvnPfLk8RpmSdRDy0Q2+vmTM54wPISiDKsRwEpetrcPo2D/xKK2LZ3yvMAZNi9PLBGBi0PVIen6vZszgWH7oFFqvkQDyzk7Ui0Q4uk3zJpoq79q1HWtByAhgSEeOF9PfZpr8EQPVMeq5clrb1SH1XPtle6+4Ku4+0ZvwM6tn0ShrDfUqBtj9YS3FWq7bnu8hdSbR7TrLwsEnEWaLevwSolyAONLn1i4hpy/ryaJdMnUAqSWoMzwaOyQsGWlKFQgqdssv53nfM2+vbJfn2Td5W3vUeYQa4iWXqBri3SBtWRrQMs0nRx85fE57raHzvJxV8=</diagram></mxfile>

.github/codecov.yml

@@ -0,0 +1,12 @@
+ignore:
+  - "watchdog/watchdog.go"
+  - "storage/store/sql/specific_postgres.go" # Can't test for postgres
+
+coverage:
+  status:
+    patch: off
+    project:
+      default:
+        target: 75%
+        threshold: null
+

.github/dependabot.yml

@@ -0,0 +1,15 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    labels: ["dependencies"]
+    schedule:
+      interval: "weekly"
+      day: "wednesday"
+  - package-ecosystem: "gomod"
+    directory: "/"
+    open-pull-requests-limit: 1
+    labels: ["dependencies"]
+    schedule:
+      interval: "weekly"
+      day: "wednesday"

.github/workflows/benchmark.yml

@@ -0,0 +1,26 @@
+name: benchmark
+on:
+  workflow_dispatch:
+    inputs:
+      repository:
+        description: "Repository to checkout. Useful for benchmarking a fork. Format should be <owner>/<repository>."
+        required: true
+        default: "TwiN/gatus"
+      ref:
+        description: "Branch, tag or SHA to checkout"
+        required: true
+        default: "master"
+jobs:
+  build:
+    name: benchmark
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.19
+          repository: "${{ github.event.inputs.repository }}"
+          ref: "${{ github.event.inputs.ref }}"
+      - uses: actions/checkout@v3
+      - name: Benchmark
+        run: go test -bench=. ./storage/store

.github/workflows/build.yml

@@ -1,31 +0,0 @@
-name: build
-on:
-  pull_request:
-    paths-ignore:
-      - '*.md'
-  push:
-    branches:
-      - master
-    paths-ignore:
-      - '*.md'
-jobs:
-  build:
-    name: Build
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    steps:
-      - name: Set up Go 1.15
-        uses: actions/setup-go@v1
-        with:
-          go-version: 1.15
-        id: go
-      - name: Check out code into the Go module directory
-        uses: actions/checkout@v2
-      - name: Build binary to make sure it works
-        run: go build -mod vendor
-      - name: Test
-        run: sudo go test -mod vendor ./... -race -coverprofile=coverage.txt -covermode=atomic
-      - name: Codecov
-        uses: codecov/codecov-action@v1.0.14
-        with:
-          file: ./coverage.txt

.github/workflows/publish-experimental.yml

@@ -0,0 +1,27 @@
+name: publish-experimental
+on: [workflow_dispatch]
+jobs:
+  publish-experimental:
+    name: publish-experimental
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v3
+      - name: Get image repository
+        run: echo IMAGE_REPOSITORY=$(echo ${{ secrets.DOCKER_USERNAME }}/${{ github.event.repository.name }} | tr '[:upper:]' '[:lower:]') >> $GITHUB_ENV
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Login to Docker Registry
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build and push docker image
+        uses: docker/build-push-action@v3
+        with:
+          platforms: linux/amd64
+          pull: true
+          push: true
+          tags: ${{ env.IMAGE_REPOSITORY }}:experimental

.github/workflows/publish-latest.yml

@@ -0,0 +1,35 @@
+name: publish-latest
+on:
+  workflow_run:
+    workflows: ["build"]
+    branches: [master]
+    types: [completed]
+concurrency:
+  group: ${{ github.workflow }}
+  cancel-in-progress: true
+jobs:
+  publish-latest:
+    name: publish-latest
+    runs-on: ubuntu-latest
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    timeout-minutes: 60
+    steps:
+      - uses: actions/checkout@v3
+      - name: Get image repository
+        run: echo IMAGE_REPOSITORY=$(echo ${{ secrets.DOCKER_USERNAME }}/${{ github.event.repository.name }} | tr '[:upper:]' '[:lower:]') >> $GITHUB_ENV
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Login to Docker Registry
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build and push docker image
+        uses: docker/build-push-action@v3
+        with:
+          platforms: linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64
+          pull: true
+          push: true
+          tags: ${{ env.IMAGE_REPOSITORY }}:latest

.github/workflows/publish-release.yml

@@ -0,0 +1,31 @@
+name: publish-release
+on:
+  release:
+    types: [published]
+jobs:
+  publish-release:
+    name: publish-release
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+    steps:
+      - uses: actions/checkout@v3
+      - name: Get image repository
+        run: echo IMAGE_REPOSITORY=$(echo ${{ secrets.DOCKER_USERNAME }}/${{ github.event.repository.name }} | tr '[:upper:]' '[:lower:]') >> $GITHUB_ENV
+      - name: Get the release
+        run: echo RELEASE=${GITHUB_REF/refs\/tags\//} >> $GITHUB_ENV
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v2
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+      - name: Login to Docker Registry
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build and push docker image
+        uses: docker/build-push-action@v3
+        with:
+          platforms: linux/amd64,linux/arm/v6,linux/arm/v7,linux/arm64
+          pull: true
+          push: true
+          tags: ${{ env.IMAGE_REPOSITORY }}:${{ env.RELEASE }},${{ env.IMAGE_REPOSITORY }}:stable

.github/workflows/publish.yml

@@ -1,32 +0,0 @@
-name: publish
-on:
-  release:
-    types: [published]
-jobs:
-  build:
-    name: Publish
-    runs-on: ubuntu-latest
-    steps:
-      - name: Check out code
-        uses: actions/checkout@v2
-      - name: Get image repository
-        run: echo IMAGE_REPOSITORY=$(echo ${{ github.repository }} | tr '[:upper:]' '[:lower:]') >> $GITHUB_ENV
-      - name: Get the release
-        run: echo RELEASE=${GITHUB_REF/refs\/tags\//} >> $GITHUB_ENV
-      - name: Set up QEMU
-        uses: docker/setup-qemu-action@v1
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v1
-      - name: Login to Docker Registry
-        uses: docker/login-action@v1
-        with:
-          username: ${{ secrets.DOCKER_USERNAME }}
-          password: ${{ secrets.DOCKER_PASSWORD }}
-      - name: Build and push docker image
-        uses: docker/build-push-action@v2
-        with:
-          platforms: linux/amd64,linux/arm/v7,linux/arm64
-          pull: true
-          push: true
-          tags: |
-            ${{ env.IMAGE_REPOSITORY }}:${{ env.RELEASE }}

.github/workflows/test.yml

@@ -0,0 +1,30 @@
+name: test
+on:
+  pull_request:
+    paths-ignore:
+      - '*.md'
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - '*.md'
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.19
+      - uses: actions/checkout@v3
+      - name: Build binary to make sure it works
+        run: go build
+      - name: Test
+        # We're using "sudo" because one of the tests leverages ping, which requires super-user privileges.
+        # As for the 'env "PATH=$PATH" "GOROOT=$GOROOT"', we need it to use the same "go" executable that
+        # was configured by the "Set up Go" step (otherwise, it'd use sudo's "go" executable)
+        run: sudo env "PATH=$PATH" "GOROOT=$GOROOT" go test ./... -race -coverprofile=coverage.txt -covermode=atomic
+      - name: Codecov
+        uses: codecov/codecov-action@v3.1.1
+        with:
+          files: ./coverage.txt

.gitignore

@@ -1,4 +1,7 @@
-bin
 .idea
 .vscode
-gatus
+*.db
+*.db-shm
+*.db-wal
+gatus
+config/config.yml

Dockerfile

@@ -3,7 +3,7 @@ FROM golang:alpine as builder
 RUN apk --update add ca-certificates
 WORKDIR /app
 COPY . ./
-RUN CGO_ENABLED=0 GOOS=linux go build -mod vendor -a -installsuffix cgo -o gatus .
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o gatus .
 
 # Run Tests inside docker image if you don't have a configured go environment
 #RUN apk update && apk add --virtual build-dependencies build-base gcc
@@ -13,7 +13,6 @@ RUN CGO_ENABLED=0 GOOS=linux go build -mod vendor -a -installsuffix cgo -o gatus
 FROM scratch
 COPY --from=builder /app/gatus .
 COPY --from=builder /app/config.yaml ./config/config.yaml
-COPY --from=builder /app/static static/
 COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
 ENV PORT=8080
 EXPOSE ${PORT}

LICENSE

@@ -0,0 +1,202 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
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+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
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+      including but not limited to software source code, documentation
+      source, and configuration files.
+
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+      transformation or translation of a Source form, including but
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+
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+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "[]"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright [yyyy] [name of copyright owner]
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+

LICENSE.md

@@ -1,9 +0,0 @@
-MIT License
-
-Copyright (c) 2020 TwinProduction
-
-Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Makefile

@@ -0,0 +1,40 @@
+BINARY=gatus
+
+# Because there's a folder called "test", we need to make the target "test" phony
+.PHONY: test
+
+install:
+	go build -mod vendor -o $(BINARY) .
+
+run:
+	GATUS_CONFIG_FILE=./config.yaml ./$(BINARY)
+
+clean:
+	rm $(BINARY)
+
+test:
+	go test ./... -cover
+
+
+##########
+# Docker #
+##########
+
+docker-build:
+	docker build -t twinproduction/gatus:latest .
+
+docker-run:
+	docker run -p 8080:8080 --name gatus twinproduction/gatus:latest
+
+docker-build-and-run: docker-build docker-run
+
+
+#############
+# Front end #
+#############
+
+frontend-build:
+	npm --prefix web/app run build
+
+frontend-run:
+	npm --prefix web/app run serve

alerting/alert/alert.go

@@ -0,0 +1,94 @@
+package alert
+
+import (
+	"errors"
+	"strings"
+)
+
+var (
+	// ErrAlertWithInvalidDescription is the error with which Gatus will panic if an alert has an invalid character
+	ErrAlertWithInvalidDescription = errors.New("alert description must not have \" or \\")
+)
+
+// Alert is a core.Endpoint's alert configuration
+type Alert struct {
+	// Type of alert (required)
+	Type Type `yaml:"type"`
+
+	// Enabled defines whether the alert is enabled
+	//
+	// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value
+	// or not for provider.ParseWithDefaultAlert to work.
+	Enabled *bool `yaml:"enabled,omitempty"`
+
+	// FailureThreshold is the number of failures in a row needed before triggering the alert
+	FailureThreshold int `yaml:"failure-threshold"`
+
+	// Description of the alert. Will be included in the alert sent.
+	//
+	// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value
+	// or not for provider.ParseWithDefaultAlert to work.
+	Description *string `yaml:"description"`
+
+	// SendOnResolved defines whether to send a second notification when the issue has been resolved
+	//
+	// This is a pointer, because it is populated by YAML and we need to know whether it was explicitly set to a value
+	// or not for provider.ParseWithDefaultAlert to work. Use Alert.IsSendingOnResolved() for a non-pointer
+	SendOnResolved *bool `yaml:"send-on-resolved"`
+
+	// SuccessThreshold defines how many successful executions must happen in a row before an ongoing incident is marked as resolved
+	SuccessThreshold int `yaml:"success-threshold"`
+
+	// ResolveKey is an optional field that is used by some providers (i.e. PagerDuty's dedup_key) to resolve
+	// ongoing/triggered incidents
+	ResolveKey string `yaml:"-"`
+
+	// Triggered is used to determine whether an alert has been triggered. When an alert is resolved, this value
+	// should be set back to false. It is used to prevent the same alert from going out twice.
+	//
+	// This value should only be modified if the provider.AlertProvider's Send function does not return an error for an
+	// alert that hasn't been triggered yet. This doubles as a lazy retry. The reason why this behavior isn't also
+	// applied for alerts that are already triggered and has become "healthy" again is to prevent a case where, for
+	// some reason, the alert provider always returns errors when trying to send the resolved notification
+	// (SendOnResolved).
+	Triggered bool `yaml:"-"`
+}
+
+// ValidateAndSetDefaults validates the alert's configuration and sets the default value of fields that have one
+func (alert *Alert) ValidateAndSetDefaults() error {
+	if alert.FailureThreshold <= 0 {
+		alert.FailureThreshold = 3
+	}
+	if alert.SuccessThreshold <= 0 {
+		alert.SuccessThreshold = 2
+	}
+	if strings.ContainsAny(alert.GetDescription(), "\"\\") {
+		return ErrAlertWithInvalidDescription
+	}
+	return nil
+}
+
+// GetDescription retrieves the description of the alert
+func (alert Alert) GetDescription() string {
+	if alert.Description == nil {
+		return ""
+	}
+	return *alert.Description
+}
+
+// IsEnabled returns whether an alert is enabled or not
+func (alert Alert) IsEnabled() bool {
+	if alert.Enabled == nil {
+		// TODO: Default to true in v5.0.0 (unless default-alert.enabled is set to false)
+		return false
+	}
+	return *alert.Enabled
+}
+
+// IsSendingOnResolved returns whether an alert is sending on resolve or not
+func (alert Alert) IsSendingOnResolved() bool {
+	if alert.SendOnResolved == nil {
+		return false
+	}
+	return *alert.SendOnResolved
+}

alerting/alert/alert_test.go

@@ -0,0 +1,85 @@
+package alert
+
+import (
+	"testing"
+)
+
+func TestAlert_ValidateAndSetDefaults(t *testing.T) {
+	invalidDescription := "\""
+	scenarios := []struct {
+		name                     string
+		alert                    Alert
+		expectedError            error
+		expectedSuccessThreshold int
+		expectedFailureThreshold int
+	}{
+		{
+			name: "valid-empty",
+			alert: Alert{
+				Description:      nil,
+				FailureThreshold: 0,
+				SuccessThreshold: 0,
+			},
+			expectedError:            nil,
+			expectedFailureThreshold: 3,
+			expectedSuccessThreshold: 2,
+		},
+		{
+			name: "invalid-description",
+			alert: Alert{
+				Description:      &invalidDescription,
+				FailureThreshold: 10,
+				SuccessThreshold: 5,
+			},
+			expectedError:            ErrAlertWithInvalidDescription,
+			expectedFailureThreshold: 10,
+			expectedSuccessThreshold: 5,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			if err := scenario.alert.ValidateAndSetDefaults(); err != scenario.expectedError {
+				t.Errorf("expected error %v, got %v", scenario.expectedError, err)
+			}
+			if scenario.alert.SuccessThreshold != scenario.expectedSuccessThreshold {
+				t.Errorf("expected success threshold %v, got %v", scenario.expectedSuccessThreshold, scenario.alert.SuccessThreshold)
+			}
+			if scenario.alert.FailureThreshold != scenario.expectedFailureThreshold {
+				t.Errorf("expected failure threshold %v, got %v", scenario.expectedFailureThreshold, scenario.alert.FailureThreshold)
+			}
+		})
+	}
+}
+
+func TestAlert_IsEnabled(t *testing.T) {
+	if (Alert{Enabled: nil}).IsEnabled() {
+		t.Error("alert.IsEnabled() should've returned false, because Enabled was set to nil")
+	}
+	if value := false; (Alert{Enabled: &value}).IsEnabled() {
+		t.Error("alert.IsEnabled() should've returned false, because Enabled was set to false")
+	}
+	if value := true; !(Alert{Enabled: &value}).IsEnabled() {
+		t.Error("alert.IsEnabled() should've returned true, because Enabled was set to true")
+	}
+}
+
+func TestAlert_GetDescription(t *testing.T) {
+	if (Alert{Description: nil}).GetDescription() != "" {
+		t.Error("alert.GetDescription() should've returned an empty string, because Description was set to nil")
+	}
+	if value := "description"; (Alert{Description: &value}).GetDescription() != value {
+		t.Error("alert.GetDescription() should've returned false, because Description was set to 'description'")
+	}
+}
+
+func TestAlert_IsSendingOnResolved(t *testing.T) {
+	if (Alert{SendOnResolved: nil}).IsSendingOnResolved() {
+		t.Error("alert.IsSendingOnResolved() should've returned false, because SendOnResolved was set to nil")
+	}
+	if value := false; (Alert{SendOnResolved: &value}).IsSendingOnResolved() {
+		t.Error("alert.IsSendingOnResolved() should've returned false, because SendOnResolved was set to false")
+	}
+	if value := true; !(Alert{SendOnResolved: &value}).IsSendingOnResolved() {
+		t.Error("alert.IsSendingOnResolved() should've returned true, because SendOnResolved was set to true")
+	}
+}

alerting/alert/type.go

@@ -0,0 +1,49 @@
+package alert
+
+// Type is the type of the alert.
+// The value will generally be the name of the alert provider
+type Type string
+
+const (
+	// TypeCustom is the Type for the custom alerting provider
+	TypeCustom Type = "custom"
+
+	// TypeDiscord is the Type for the discord alerting provider
+	TypeDiscord Type = "discord"
+
+	// TypeEmail is the Type for the email alerting provider
+	TypeEmail Type = "email"
+
+	// TypeGoogleChat is the Type for the googlechat alerting provider
+	TypeGoogleChat Type = "googlechat"
+
+	// TypeMatrix is the Type for the matrix alerting provider
+	TypeMatrix Type = "matrix"
+
+	// TypeMattermost is the Type for the mattermost alerting provider
+	TypeMattermost Type = "mattermost"
+
+	// TypeMessagebird is the Type for the messagebird alerting provider
+	TypeMessagebird Type = "messagebird"
+
+	// TypeNtfy is the Type for the ntfy alerting provider
+	TypeNtfy Type = "ntfy"
+
+	// TypeOpsgenie is the Type for the opsgenie alerting provider
+	TypeOpsgenie Type = "opsgenie"
+
+	// TypePagerDuty is the Type for the pagerduty alerting provider
+	TypePagerDuty Type = "pagerduty"
+
+	// TypeSlack is the Type for the slack alerting provider
+	TypeSlack Type = "slack"
+
+	// TypeTeams is the Type for the teams alerting provider
+	TypeTeams Type = "teams"
+
+	// TypeTelegram is the Type for the telegram alerting provider
+	TypeTelegram Type = "telegram"
+
+	// TypeTwilio is the Type for the twilio alerting provider
+	TypeTwilio Type = "twilio"
+)

alerting/config.go

@@ -1,31 +1,156 @@
 package alerting
 
 import (
-	"github.com/TwinProduction/gatus/alerting/provider/custom"
-	"github.com/TwinProduction/gatus/alerting/provider/mattermost"
-	"github.com/TwinProduction/gatus/alerting/provider/messagebird"
-	"github.com/TwinProduction/gatus/alerting/provider/pagerduty"
-	"github.com/TwinProduction/gatus/alerting/provider/slack"
-	"github.com/TwinProduction/gatus/alerting/provider/twilio"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/alerting/provider"
+	"github.com/TwiN/gatus/v4/alerting/provider/custom"
+	"github.com/TwiN/gatus/v4/alerting/provider/discord"
+	"github.com/TwiN/gatus/v4/alerting/provider/email"
+	"github.com/TwiN/gatus/v4/alerting/provider/googlechat"
+	"github.com/TwiN/gatus/v4/alerting/provider/matrix"
+	"github.com/TwiN/gatus/v4/alerting/provider/mattermost"
+	"github.com/TwiN/gatus/v4/alerting/provider/messagebird"
+	"github.com/TwiN/gatus/v4/alerting/provider/ntfy"
+	"github.com/TwiN/gatus/v4/alerting/provider/opsgenie"
+	"github.com/TwiN/gatus/v4/alerting/provider/pagerduty"
+	"github.com/TwiN/gatus/v4/alerting/provider/slack"
+	"github.com/TwiN/gatus/v4/alerting/provider/teams"
+	"github.com/TwiN/gatus/v4/alerting/provider/telegram"
+	"github.com/TwiN/gatus/v4/alerting/provider/twilio"
 )
 
 // Config is the configuration for alerting providers
 type Config struct {
-	// Slack is the configuration for the slack alerting provider
-	Slack *slack.AlertProvider `yaml:"slack"`
+	// Custom is the configuration for the custom alerting provider
+	Custom *custom.AlertProvider `yaml:"custom,omitempty"`
+
+	// GoogleChat is the configuration for the Google chat alerting provider
+	GoogleChat *googlechat.AlertProvider `yaml:"googlechat,omitempty"`
+
+	// Discord is the configuration for the discord alerting provider
+	Discord *discord.AlertProvider `yaml:"discord,omitempty"`
+
+	// Email is the configuration for the email alerting provider
+	Email *email.AlertProvider `yaml:"email,omitempty"`
+
+	// Matrix is the configuration for the matrix alerting provider
+	Matrix *matrix.AlertProvider `yaml:"matrix,omitempty"`
 
 	// Mattermost is the configuration for the mattermost alerting provider
-	Mattermost *mattermost.AlertProvider `yaml:"mattermost"`
+	Mattermost *mattermost.AlertProvider `yaml:"mattermost,omitempty"`
 
 	// Messagebird is the configuration for the messagebird alerting provider
-	Messagebird *messagebird.AlertProvider `yaml:"messagebird"`
+	Messagebird *messagebird.AlertProvider `yaml:"messagebird,omitempty"`
 
-	// Pagerduty is the configuration for the pagerduty alerting provider
-	PagerDuty *pagerduty.AlertProvider `yaml:"pagerduty"`
+	// Ntfy is the configuration for the ntfy alerting provider
+	Ntfy *ntfy.AlertProvider `yaml:"ntfy,omitempty"`
+
+	// Opsgenie is the configuration for the opsgenie alerting provider
+	Opsgenie *opsgenie.AlertProvider `yaml:"opsgenie,omitempty"`
+
+	// PagerDuty is the configuration for the pagerduty alerting provider
+	PagerDuty *pagerduty.AlertProvider `yaml:"pagerduty,omitempty"`
+
+	// Slack is the configuration for the slack alerting provider
+	Slack *slack.AlertProvider `yaml:"slack,omitempty"`
+
+	// Teams is the configuration for the teams alerting provider
+	Teams *teams.AlertProvider `yaml:"teams,omitempty"`
+
+	// Telegram is the configuration for the telegram alerting provider
+	Telegram *telegram.AlertProvider `yaml:"telegram,omitempty"`
 
 	// Twilio is the configuration for the twilio alerting provider
-	Twilio *twilio.AlertProvider `yaml:"twilio"`
-
-	// Custom is the configuration for the custom alerting provider
-	Custom *custom.AlertProvider `yaml:"custom"`
+	Twilio *twilio.AlertProvider `yaml:"twilio,omitempty"`
+}
+
+// GetAlertingProviderByAlertType returns an provider.AlertProvider by its corresponding alert.Type
+func (config Config) GetAlertingProviderByAlertType(alertType alert.Type) provider.AlertProvider {
+	switch alertType {
+	case alert.TypeCustom:
+		if config.Custom == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Custom
+	case alert.TypeDiscord:
+		if config.Discord == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Discord
+	case alert.TypeEmail:
+		if config.Email == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Email
+	case alert.TypeGoogleChat:
+		if config.GoogleChat == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.GoogleChat
+	case alert.TypeMatrix:
+		if config.Matrix == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Matrix
+	case alert.TypeMattermost:
+		if config.Mattermost == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Mattermost
+	case alert.TypeMessagebird:
+		if config.Messagebird == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Messagebird
+	case alert.TypeNtfy:
+		if config.Ntfy == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Ntfy
+	case alert.TypeOpsgenie:
+		if config.Opsgenie == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Opsgenie
+	case alert.TypePagerDuty:
+		if config.PagerDuty == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.PagerDuty
+	case alert.TypeSlack:
+		if config.Slack == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Slack
+	case alert.TypeTeams:
+		if config.Teams == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Teams
+	case alert.TypeTelegram:
+		if config.Telegram == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Telegram
+	case alert.TypeTwilio:
+		if config.Twilio == nil {
+			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
+			return nil
+		}
+		return config.Twilio
+	}
+	return nil
 }

alerting/provider/custom/custom.go

@@ -3,88 +3,96 @@ package custom
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"net/http"
 	"strings"
 
-	"github.com/TwinProduction/gatus/client"
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
 )
 
 // AlertProvider is the configuration necessary for sending an alert using a custom HTTP request
 // Technically, all alert providers should be reachable using the custom alert provider
 type AlertProvider struct {
-	URL      string            `yaml:"url"`
-	Method   string            `yaml:"method,omitempty"`
-	Insecure bool              `yaml:"insecure,omitempty"`
-	Body     string            `yaml:"body,omitempty"`
-	Headers  map[string]string `yaml:"headers,omitempty"`
+	URL          string                       `yaml:"url"`
+	Method       string                       `yaml:"method,omitempty"`
+	Body         string                       `yaml:"body,omitempty"`
+	Headers      map[string]string            `yaml:"headers,omitempty"`
+	Placeholders map[string]map[string]string `yaml:"placeholders,omitempty"`
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
 }
 
 // IsValid returns whether the provider's configuration is valid
 func (provider *AlertProvider) IsValid() bool {
-	return len(provider.URL) > 0
+	if provider.ClientConfig == nil {
+		provider.ClientConfig = client.GetDefaultConfig()
+	}
+	return len(provider.URL) > 0 && provider.ClientConfig != nil
 }
 
-// ToCustomAlertProvider converts the provider into a custom.AlertProvider
-func (provider *AlertProvider) ToCustomAlertProvider(service *core.Service, alert *core.Alert, result *core.Result, resolved bool) *AlertProvider {
-	return provider
+// GetAlertStatePlaceholderValue returns the Placeholder value for ALERT_TRIGGERED_OR_RESOLVED if configured
+func (provider *AlertProvider) GetAlertStatePlaceholderValue(resolved bool) string {
+	status := "TRIGGERED"
+	if resolved {
+		status = "RESOLVED"
+	}
+	if _, ok := provider.Placeholders["ALERT_TRIGGERED_OR_RESOLVED"]; ok {
+		if val, ok := provider.Placeholders["ALERT_TRIGGERED_OR_RESOLVED"][status]; ok {
+			return val
+		}
+	}
+	return status
 }
 
-func (provider *AlertProvider) buildHTTPRequest(serviceName, alertDescription string, resolved bool) *http.Request {
-	body := provider.Body
-	providerURL := provider.URL
-	method := provider.Method
-	if strings.Contains(body, "[ALERT_DESCRIPTION]") {
-		body = strings.ReplaceAll(body, "[ALERT_DESCRIPTION]", alertDescription)
-	}
-	if strings.Contains(body, "[SERVICE_NAME]") {
-		body = strings.ReplaceAll(body, "[SERVICE_NAME]", serviceName)
-	}
-	if strings.Contains(body, "[ALERT_TRIGGERED_OR_RESOLVED]") {
-		if resolved {
-			body = strings.ReplaceAll(body, "[ALERT_TRIGGERED_OR_RESOLVED]", "RESOLVED")
-		} else {
-			body = strings.ReplaceAll(body, "[ALERT_TRIGGERED_OR_RESOLVED]", "TRIGGERED")
-		}
-	}
-	if strings.Contains(providerURL, "[ALERT_DESCRIPTION]") {
-		providerURL = strings.ReplaceAll(providerURL, "[ALERT_DESCRIPTION]", alertDescription)
-	}
-	if strings.Contains(providerURL, "[SERVICE_NAME]") {
-		providerURL = strings.ReplaceAll(providerURL, "[SERVICE_NAME]", serviceName)
-	}
-	if strings.Contains(providerURL, "[ALERT_TRIGGERED_OR_RESOLVED]") {
-		if resolved {
-			providerURL = strings.ReplaceAll(providerURL, "[ALERT_TRIGGERED_OR_RESOLVED]", "RESOLVED")
-		} else {
-			providerURL = strings.ReplaceAll(providerURL, "[ALERT_TRIGGERED_OR_RESOLVED]", "TRIGGERED")
-		}
+func (provider *AlertProvider) buildHTTPRequest(endpoint *core.Endpoint, alert *alert.Alert, resolved bool) *http.Request {
+	body, url, method := provider.Body, provider.URL, provider.Method
+	body = strings.ReplaceAll(body, "[ALERT_DESCRIPTION]", alert.GetDescription())
+	url = strings.ReplaceAll(url, "[ALERT_DESCRIPTION]", alert.GetDescription())
+	body = strings.ReplaceAll(body, "[ENDPOINT_NAME]", endpoint.Name)
+	url = strings.ReplaceAll(url, "[ENDPOINT_NAME]", endpoint.Name)
+	body = strings.ReplaceAll(body, "[ENDPOINT_GROUP]", endpoint.Group)
+	url = strings.ReplaceAll(url, "[ENDPOINT_GROUP]", endpoint.Group)
+	body = strings.ReplaceAll(body, "[ENDPOINT_URL]", endpoint.URL)
+	url = strings.ReplaceAll(url, "[ENDPOINT_URL]", endpoint.URL)
+	if resolved {
+		body = strings.ReplaceAll(body, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(true))
+		url = strings.ReplaceAll(url, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(true))
+	} else {
+		body = strings.ReplaceAll(body, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(false))
+		url = strings.ReplaceAll(url, "[ALERT_TRIGGERED_OR_RESOLVED]", provider.GetAlertStatePlaceholderValue(false))
 	}
 	if len(method) == 0 {
 		method = http.MethodGet
 	}
 	bodyBuffer := bytes.NewBuffer([]byte(body))
-	request, _ := http.NewRequest(method, providerURL, bodyBuffer)
+	request, _ := http.NewRequest(method, url, bodyBuffer)
 	for k, v := range provider.Headers {
 		request.Header.Set(k, v)
 	}
 	return request
 }
 
-// Send a request to the alert provider and return the body
-func (provider *AlertProvider) Send(serviceName, alertDescription string, resolved bool) ([]byte, error) {
-	request := provider.buildHTTPRequest(serviceName, alertDescription, resolved)
-	response, err := client.GetHTTPClient(provider.Insecure).Do(request)
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	request := provider.buildHTTPRequest(endpoint, alert, resolved)
+	response, err := client.GetHTTPClient(provider.ClientConfig).Do(request)
 	if err != nil {
-		return nil, err
+		return err
 	}
+	defer response.Body.Close()
 	if response.StatusCode > 399 {
-		body, err := ioutil.ReadAll(response.Body)
-		if err != nil {
-			return nil, fmt.Errorf("call to provider alert returned status code %d", response.StatusCode)
-		}
-		return nil, fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
 	}
-	return ioutil.ReadAll(response.Body)
+	return err
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
 }

alerting/provider/custom/custom_test.go

@@ -1,70 +1,226 @@
 package custom
 
 import (
-	"io/ioutil"
+	"fmt"
+	"io"
+	"net/http"
 	"testing"
 
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
 )
 
 func TestAlertProvider_IsValid(t *testing.T) {
-	invalidProvider := AlertProvider{URL: ""}
-	if invalidProvider.IsValid() {
-		t.Error("provider shouldn't have been valid")
+	t.Run("invalid-provider", func(t *testing.T) {
+		invalidProvider := AlertProvider{URL: ""}
+		if invalidProvider.IsValid() {
+			t.Error("provider shouldn't have been valid")
+		}
+	})
+	t.Run("valid-provider", func(t *testing.T) {
+		validProvider := AlertProvider{URL: "https://example.com"}
+		if validProvider.ClientConfig != nil {
+			t.Error("provider client config should have been nil prior to IsValid() being executed")
+		}
+		if !validProvider.IsValid() {
+			t.Error("provider should've been valid")
+		}
+		if validProvider.ClientConfig == nil {
+			t.Error("provider client config should have been set after IsValid() was executed")
+		}
+	})
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
 	}
-	validProvider := AlertProvider{URL: "http://example.com"}
-	if !validProvider.IsValid() {
-		t.Error("provider should've been valid")
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
 	}
 }
 
-func TestAlertProvider_buildHTTPRequestWhenResolved(t *testing.T) {
-	const (
-		ExpectedURL  = "http://example.com/service-name?event=RESOLVED&description=alert-description"
-		ExpectedBody = "service-name,alert-description,RESOLVED"
-	)
+func TestAlertProvider_buildHTTPRequest(t *testing.T) {
 	customAlertProvider := &AlertProvider{
-		URL:     "http://example.com/[SERVICE_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]",
-		Body:    "[SERVICE_NAME],[ALERT_DESCRIPTION],[ALERT_TRIGGERED_OR_RESOLVED]",
+		URL:  "https://example.com/[ENDPOINT_GROUP]/[ENDPOINT_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]&url=[ENDPOINT_URL]",
+		Body: "[ENDPOINT_NAME],[ENDPOINT_GROUP],[ALERT_DESCRIPTION],[ENDPOINT_URL],[ALERT_TRIGGERED_OR_RESOLVED]",
+	}
+	alertDescription := "alert-description"
+	scenarios := []struct {
+		AlertProvider *AlertProvider
+		Resolved      bool
+		ExpectedURL   string
+		ExpectedBody  string
+	}{
+		{
+			AlertProvider: customAlertProvider,
+			Resolved:      true,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=RESOLVED&description=alert-description&url=https://example.com",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,https://example.com,RESOLVED",
+		},
+		{
+			AlertProvider: customAlertProvider,
+			Resolved:      false,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=TRIGGERED&description=alert-description&url=https://example.com",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,https://example.com,TRIGGERED",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(fmt.Sprintf("resolved-%v-with-default-placeholders", scenario.Resolved), func(t *testing.T) {
+			request := customAlertProvider.buildHTTPRequest(
+				&core.Endpoint{Name: "endpoint-name", Group: "endpoint-group", URL: "https://example.com"},
+				&alert.Alert{Description: &alertDescription},
+				scenario.Resolved,
+			)
+			if request.URL.String() != scenario.ExpectedURL {
+				t.Error("expected URL to be", scenario.ExpectedURL, "got", request.URL.String())
+			}
+			body, _ := io.ReadAll(request.Body)
+			if string(body) != scenario.ExpectedBody {
+				t.Error("expected body to be", scenario.ExpectedBody, "got", string(body))
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildHTTPRequestWithCustomPlaceholder(t *testing.T) {
+	customAlertProvider := &AlertProvider{
+		URL:     "https://example.com/[ENDPOINT_GROUP]/[ENDPOINT_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]",
+		Body:    "[ENDPOINT_NAME],[ENDPOINT_GROUP],[ALERT_DESCRIPTION],[ALERT_TRIGGERED_OR_RESOLVED]",
 		Headers: nil,
+		Placeholders: map[string]map[string]string{
+			"ALERT_TRIGGERED_OR_RESOLVED": {
+				"RESOLVED":  "fixed",
+				"TRIGGERED": "boom",
+			},
+		},
 	}
-	request := customAlertProvider.buildHTTPRequest("service-name", "alert-description", true)
-	if request.URL.String() != ExpectedURL {
-		t.Error("expected URL to be", ExpectedURL, "was", request.URL.String())
+	alertDescription := "alert-description"
+	scenarios := []struct {
+		AlertProvider *AlertProvider
+		Resolved      bool
+		ExpectedURL   string
+		ExpectedBody  string
+	}{
+		{
+			AlertProvider: customAlertProvider,
+			Resolved:      true,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=fixed&description=alert-description",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,fixed",
+		},
+		{
+			AlertProvider: customAlertProvider,
+			Resolved:      false,
+			ExpectedURL:   "https://example.com/endpoint-group/endpoint-name?event=boom&description=alert-description",
+			ExpectedBody:  "endpoint-name,endpoint-group,alert-description,boom",
+		},
 	}
-	body, _ := ioutil.ReadAll(request.Body)
-	if string(body) != ExpectedBody {
-		t.Error("expected body to be", ExpectedBody, "was", string(body))
+	for _, scenario := range scenarios {
+		t.Run(fmt.Sprintf("resolved-%v-with-custom-placeholders", scenario.Resolved), func(t *testing.T) {
+			request := customAlertProvider.buildHTTPRequest(
+				&core.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&alert.Alert{Description: &alertDescription},
+				scenario.Resolved,
+			)
+			if request.URL.String() != scenario.ExpectedURL {
+				t.Error("expected URL to be", scenario.ExpectedURL, "got", request.URL.String())
+			}
+			body, _ := io.ReadAll(request.Body)
+			if string(body) != scenario.ExpectedBody {
+				t.Error("expected body to be", scenario.ExpectedBody, "got", string(body))
+			}
+		})
 	}
 }
 
-func TestAlertProvider_buildHTTPRequestWhenTriggered(t *testing.T) {
-	const (
-		ExpectedURL  = "http://example.com/service-name?event=TRIGGERED&description=alert-description"
-		ExpectedBody = "service-name,alert-description,TRIGGERED"
-	)
+func TestAlertProvider_GetAlertStatePlaceholderValueDefaults(t *testing.T) {
 	customAlertProvider := &AlertProvider{
-		URL:     "http://example.com/[SERVICE_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]",
-		Body:    "[SERVICE_NAME],[ALERT_DESCRIPTION],[ALERT_TRIGGERED_OR_RESOLVED]",
-		Headers: map[string]string{"Authorization": "Basic hunter2"},
+		URL:  "https://example.com/[ENDPOINT_NAME]?event=[ALERT_TRIGGERED_OR_RESOLVED]&description=[ALERT_DESCRIPTION]",
+		Body: "[ENDPOINT_NAME],[ENDPOINT_GROUP],[ALERT_DESCRIPTION],[ALERT_TRIGGERED_OR_RESOLVED]",
 	}
-	request := customAlertProvider.buildHTTPRequest("service-name", "alert-description", false)
-	if request.URL.String() != ExpectedURL {
-		t.Error("expected URL to be", ExpectedURL, "was", request.URL.String())
+	if customAlertProvider.GetAlertStatePlaceholderValue(true) != "RESOLVED" {
+		t.Error("expected RESOLVED, got", customAlertProvider.GetAlertStatePlaceholderValue(true))
 	}
-	body, _ := ioutil.ReadAll(request.Body)
-	if string(body) != ExpectedBody {
-		t.Error("expected body to be", ExpectedBody, "was", string(body))
+	if customAlertProvider.GetAlertStatePlaceholderValue(false) != "TRIGGERED" {
+		t.Error("expected TRIGGERED, got", customAlertProvider.GetAlertStatePlaceholderValue(false))
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProvider(t *testing.T) {
-	provider := AlertProvider{URL: "http://example.com"}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, true)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
 	}
-	if customAlertProvider != customAlertProvider {
-		t.Error("customAlertProvider should've been equal to customAlertProvider")
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
 	}
 }

alerting/provider/discord/discord.go

@@ -0,0 +1,143 @@
+package discord
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+// AlertProvider is the configuration necessary for sending an alert using Discord
+type AlertProvider struct {
+	WebhookURL string `yaml:"webhook-url"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group      string `yaml:"group"`
+	WebhookURL string `yaml:"webhook-url"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return len(provider.WebhookURL) > 0
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, provider.getWebhookURLForGroup(endpoint.Group), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Content string  `json:"content"`
+	Embeds  []Embed `json:"embeds"`
+}
+
+type Embed struct {
+	Title       string  `json:"title"`
+	Description string  `json:"description"`
+	Color       int     `json:"color"`
+	Fields      []Field `json:"fields"`
+}
+
+type Field struct {
+	Name   string `json:"name"`
+	Value  string `json:"value"`
+	Inline bool   `json:"inline"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	var message, results string
+	var colorCode int
+	if resolved {
+		message = fmt.Sprintf("An alert for **%s** has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
+		colorCode = 3066993
+	} else {
+		message = fmt.Sprintf("An alert for **%s** has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
+		colorCode = 15158332
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = ":white_check_mark:"
+		} else {
+			prefix = ":x:"
+		}
+		results += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
+	}
+	body, _ := json.Marshal(Body{
+		Content: "",
+		Embeds: []Embed{
+			{
+				Title:       ":helmet_with_white_cross: Gatus",
+				Description: message + description,
+				Color:       colorCode,
+				Fields: []Field{
+					{
+						Name:   "Condition results",
+						Value:  results,
+						Inline: false,
+					},
+				},
+			},
+		},
+	})
+	return body
+}
+
+// getWebhookURLForGroup returns the appropriate Webhook URL integration to for a given group
+func (provider *AlertProvider) getWebhookURLForGroup(group string) string {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.WebhookURL
+			}
+		}
+	}
+	return provider.WebhookURL
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/discord/discord_test.go

@@ -0,0 +1,259 @@
+package discord
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
+)
+
+func TestAlertProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{WebhookURL: ""}
+	if invalidProvider.IsValid() {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{WebhookURL: "http://example.com"}
+	if !validProvider.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "",
+			},
+		},
+	}
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "",
+				Group:      "group",
+			},
+		},
+	}
+	if providerWithInvalidOverrideTo.IsValid() {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		WebhookURL: "http://example.com",
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "group",
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"content\":\"\",\"embeds\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"description\":\"An alert for **endpoint-name** has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"color\":15158332,\"fields\":[{\"name\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n:x: - `[BODY] != \\\"\\\"`\\n\",\"inline\":false}]}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"content\":\"\",\"embeds\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"description\":\"An alert for **endpoint-name** has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"color\":3066993,\"fields\":[{\"name\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n:white_check_mark: - `[BODY] != \\\"\\\"`\\n\",\"inline\":false}]}]}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+						{Condition: "[BODY] != \"\"", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getWebhookURLForGroup(t *testing.T) {
+	tests := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput string
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example01.com",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			if got := tt.Provider.getWebhookURLForGroup(tt.InputGroup); got != tt.ExpectedOutput {
+				t.Errorf("AlertProvider.getWebhookURLForGroup() = %v, want %v", got, tt.ExpectedOutput)
+			}
+		})
+	}
+}

alerting/provider/email/email.go

@@ -0,0 +1,109 @@
+package email
+
+import (
+	"fmt"
+	"math"
+	"strings"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/core"
+	gomail "gopkg.in/mail.v2"
+)
+
+// AlertProvider is the configuration necessary for sending an alert using SMTP
+type AlertProvider struct {
+	From     string `yaml:"from"`
+	Username string `yaml:"username"`
+	Password string `yaml:"password"`
+	Host     string `yaml:"host"`
+	Port     int    `yaml:"port"`
+	To       string `yaml:"to"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group string `yaml:"group"`
+	To    string `yaml:"to"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.To) == 0 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+
+	return len(provider.From) > 0 && len(provider.Password) > 0 && len(provider.Host) > 0 && len(provider.To) > 0 && provider.Port > 0 && provider.Port < math.MaxUint16
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	var username string
+	if len(provider.Username) > 0 {
+		username = provider.Username
+	} else {
+		username = provider.From
+	}
+	subject, body := provider.buildMessageSubjectAndBody(endpoint, alert, result, resolved)
+	m := gomail.NewMessage()
+	m.SetHeader("From", provider.From)
+	m.SetHeader("To", strings.Split(provider.getToForGroup(endpoint.Group), ",")...)
+	m.SetHeader("Subject", subject)
+	m.SetBody("text/plain", body)
+	d := gomail.NewDialer(provider.Host, provider.Port, username, provider.Password)
+	return d.DialAndSend(m)
+}
+
+// buildMessageSubjectAndBody builds the message subject and body
+func (provider *AlertProvider) buildMessageSubjectAndBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) (string, string) {
+	var subject, message, results string
+	if resolved {
+		subject = fmt.Sprintf("[%s] Alert resolved", endpoint.DisplayName())
+		message = fmt.Sprintf("An alert for %s has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
+	} else {
+		subject = fmt.Sprintf("[%s] Alert triggered", endpoint.DisplayName())
+		message = fmt.Sprintf("An alert for %s has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		results += fmt.Sprintf("%s %s\n", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = "\n\nAlert description: " + alertDescription
+	}
+	return subject, message + description + "\n\nCondition results:\n" + results
+}
+
+// getToForGroup returns the appropriate email integration to for a given group
+func (provider *AlertProvider) getToForGroup(group string) string {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.To
+			}
+		}
+	}
+	return provider.To
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/email/email_test.go

@@ -0,0 +1,183 @@
+package email
+
+import (
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+func TestAlertDefaultProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{}
+	if invalidProvider.IsValid() {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{From: "from@example.com", Password: "password", Host: "smtp.gmail.com", Port: 587, To: "to@example.com"}
+	if !validProvider.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				To:    "to@example.com",
+				Group: "",
+			},
+		},
+	}
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				To:    "",
+				Group: "group",
+			},
+		},
+	}
+	if providerWithInvalidOverrideTo.IsValid() {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		From:     "from@example.com",
+		Password: "password",
+		Host:     "smtp.gmail.com",
+		Port:     587,
+		To:       "to@example.com",
+		Overrides: []Override{
+			{
+				To:    "to@example.com",
+				Group: "group",
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name            string
+		Provider        AlertProvider
+		Alert           alert.Alert
+		Resolved        bool
+		ExpectedSubject string
+		ExpectedBody    string
+	}{
+		{
+			Name:            "triggered",
+			Provider:        AlertProvider{},
+			Alert:           alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:        false,
+			ExpectedSubject: "[endpoint-name] Alert triggered",
+			ExpectedBody:    "An alert for endpoint-name has been triggered due to having failed 3 time(s) in a row\n\nAlert description: description-1\n\nCondition results:\n❌ [CONNECTED] == true\n❌ [STATUS] == 200\n",
+		},
+		{
+			Name:            "resolved",
+			Provider:        AlertProvider{},
+			Alert:           alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:        true,
+			ExpectedSubject: "[endpoint-name] Alert resolved",
+			ExpectedBody:    "An alert for endpoint-name has been resolved after passing successfully 5 time(s) in a row\n\nAlert description: description-2\n\nCondition results:\n✅ [CONNECTED] == true\n✅ [STATUS] == 200\n",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			subject, body := scenario.Provider.buildMessageSubjectAndBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if subject != scenario.ExpectedSubject {
+				t.Errorf("expected subject to be %s, got %s", scenario.ExpectedSubject, subject)
+			}
+			if body != scenario.ExpectedBody {
+				t.Errorf("expected body to be %s, got %s", scenario.ExpectedBody, body)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getToForGroup(t *testing.T) {
+	tests := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput string
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				To:        "to@example.com",
+				Overrides: nil,
+			},
+			InputGroup:     "",
+			ExpectedOutput: "to@example.com",
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				To:        "to@example.com",
+				Overrides: nil,
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "to@example.com",
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				To: "to@example.com",
+				Overrides: []Override{
+					{
+						Group: "group",
+						To:    "to01@example.com",
+					},
+				},
+			},
+			InputGroup:     "",
+			ExpectedOutput: "to@example.com",
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				To: "to@example.com",
+				Overrides: []Override{
+					{
+						Group: "group",
+						To:    "to01@example.com",
+					},
+				},
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "to01@example.com",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			if got := tt.Provider.getToForGroup(tt.InputGroup); got != tt.ExpectedOutput {
+				t.Errorf("AlertProvider.getToForGroup() = %v, want %v", got, tt.ExpectedOutput)
+			}
+		})
+	}
+}

alerting/provider/googlechat/googlechat.go

@@ -0,0 +1,201 @@
+package googlechat
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+// AlertProvider is the configuration necessary for sending an alert using Google chat
+type AlertProvider struct {
+	WebhookURL string `yaml:"webhook-url"`
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group      string `yaml:"group"`
+	WebhookURL string `yaml:"webhook-url"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	if provider.ClientConfig == nil {
+		provider.ClientConfig = client.GetDefaultConfig()
+	}
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return len(provider.WebhookURL) > 0
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, provider.getWebhookURLForGroup(endpoint.Group), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(provider.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Cards []Cards `json:"cards"`
+}
+
+type Cards struct {
+	Sections []Sections `json:"sections"`
+}
+
+type Sections struct {
+	Widgets []Widgets `json:"widgets"`
+}
+
+type Widgets struct {
+	KeyValue *KeyValue `json:"keyValue,omitempty"`
+	Buttons  []Buttons `json:"buttons,omitempty"`
+}
+
+type KeyValue struct {
+	TopLabel         string `json:"topLabel,omitempty"`
+	Content          string `json:"content,omitempty"`
+	ContentMultiline string `json:"contentMultiline,omitempty"`
+	BottomLabel      string `json:"bottomLabel,omitempty"`
+	Icon             string `json:"icon,omitempty"`
+}
+
+type Buttons struct {
+	TextButton TextButton `json:"textButton"`
+}
+
+type TextButton struct {
+	Text    string  `json:"text"`
+	OnClick OnClick `json:"onClick"`
+}
+
+type OnClick struct {
+	OpenLink OpenLink `json:"openLink"`
+}
+
+type OpenLink struct {
+	URL string `json:"url"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	var message, color string
+	if resolved {
+		color = "#36A64F"
+		message = fmt.Sprintf("<font color='%s'>An alert has been resolved after passing successfully %d time(s) in a row</font>", color, alert.SuccessThreshold)
+	} else {
+		color = "#DD0000"
+		message = fmt.Sprintf("<font color='%s'>An alert has been triggered due to having failed %d time(s) in a row</font>", color, alert.FailureThreshold)
+	}
+	var results string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		results += fmt.Sprintf("%s   %s<br>", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":: " + alertDescription
+	}
+	payload := Body{
+		Cards: []Cards{
+			{
+				Sections: []Sections{
+					{
+						Widgets: []Widgets{
+							{
+								KeyValue: &KeyValue{
+									TopLabel:         endpoint.DisplayName(),
+									Content:          message,
+									ContentMultiline: "true",
+									BottomLabel:      description,
+									Icon:             "BOOKMARK",
+								},
+							},
+							{
+								KeyValue: &KeyValue{
+									TopLabel:         "Condition results",
+									Content:          results,
+									ContentMultiline: "true",
+									Icon:             "DESCRIPTION",
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+	if endpoint.Type() == core.EndpointTypeHTTP {
+		// We only include a button targeting the URL if the endpoint is an HTTP endpoint
+		// If the URL isn't prefixed with https://, Google Chat will just display a blank message aynways.
+		// See https://github.com/TwiN/gatus/issues/362
+		payload.Cards[0].Sections[0].Widgets = append(payload.Cards[0].Sections[0].Widgets, Widgets{
+			Buttons: []Buttons{
+				{
+					TextButton: TextButton{
+						Text:    "URL",
+						OnClick: OnClick{OpenLink: OpenLink{URL: endpoint.URL}},
+					},
+				},
+			},
+		})
+	}
+	body, _ := json.Marshal(payload)
+	return body
+}
+
+// getWebhookURLForGroup returns the appropriate Webhook URL integration to for a given group
+func (provider *AlertProvider) getWebhookURLForGroup(group string) string {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.WebhookURL
+			}
+		}
+	}
+	return provider.WebhookURL
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/googlechat/googlechat_test.go

@@ -0,0 +1,277 @@
+package googlechat
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
+)
+
+func TestAlertDefaultProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{WebhookURL: ""}
+	if invalidProvider.IsValid() {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{WebhookURL: "http://example.com"}
+	if !validProvider.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "",
+			},
+		},
+	}
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "",
+				Group:      "group",
+			},
+		},
+	}
+	if providerWithInvalidOverrideTo.IsValid() {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		WebhookURL: "http://example.com",
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "group",
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name", Group: "endpoint-group"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Endpoint     core.Endpoint
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Endpoint:     core.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#DD0000'\u003eAn alert has been triggered due to having failed 3 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-1","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"❌   [CONNECTED] == true\u003cbr\u003e❌   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}},{"buttons":[{"textButton":{"text":"URL","onClick":{"openLink":{"url":"https://example.org"}}}}]}]}]}]}`,
+		},
+		{
+			Name:         "resolved",
+			Endpoint:     core.Endpoint{Name: "endpoint-name", URL: "https://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#36A64F'\u003eAn alert has been resolved after passing successfully 5 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-2","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"✅   [CONNECTED] == true\u003cbr\u003e✅   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}},{"buttons":[{"textButton":{"text":"URL","onClick":{"openLink":{"url":"https://example.org"}}}}]}]}]}]}`,
+		},
+		{
+			Name:         "icmp-should-not-include-url", // See https://github.com/TwiN/gatus/issues/362
+			Endpoint:     core.Endpoint{Name: "endpoint-name", URL: "icmp://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#DD0000'\u003eAn alert has been triggered due to having failed 3 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-1","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"❌   [CONNECTED] == true\u003cbr\u003e❌   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}}]}]}]}`,
+		},
+		{
+			Name:         "tcp-should-not-include-url", // See https://github.com/TwiN/gatus/issues/362
+			Endpoint:     core.Endpoint{Name: "endpoint-name", URL: "tcp://example.org"},
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: `{"cards":[{"sections":[{"widgets":[{"keyValue":{"topLabel":"endpoint-name","content":"\u003cfont color='#DD0000'\u003eAn alert has been triggered due to having failed 3 time(s) in a row\u003c/font\u003e","contentMultiline":"true","bottomLabel":":: description-1","icon":"BOOKMARK"}},{"keyValue":{"topLabel":"Condition results","content":"❌   [CONNECTED] == true\u003cbr\u003e❌   [STATUS] == 200\u003cbr\u003e","contentMultiline":"true","icon":"DESCRIPTION"}}]}]}]}`,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getWebhookURLForGroup(t *testing.T) {
+	tests := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput string
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example01.com",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			if got := tt.Provider.getWebhookURLForGroup(tt.InputGroup); got != tt.ExpectedOutput {
+				t.Errorf("AlertProvider.getToForGroup() = %v, want %v", got, tt.ExpectedOutput)
+			}
+		})
+	}
+}

alerting/provider/matrix/matrix.go

@@ -0,0 +1,190 @@
+package matrix
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"math/rand"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+// AlertProvider is the configuration necessary for sending an alert using Matrix
+type AlertProvider struct {
+	MatrixProviderConfig `yaml:",inline"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group string `yaml:"group"`
+
+	MatrixProviderConfig `yaml:",inline"`
+}
+
+const defaultHomeserverURL = "https://matrix-client.matrix.org"
+
+type MatrixProviderConfig struct {
+	// ServerURL is the custom homeserver to use (optional)
+	ServerURL string `yaml:"server-url"`
+
+	// AccessToken is the bot user's access token to send messages
+	AccessToken string `yaml:"access-token"`
+
+	// InternalRoomID is the room that the bot user has permissions to send messages to
+	InternalRoomID string `yaml:"internal-room-id"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.AccessToken) == 0 || len(override.InternalRoomID) == 0 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return len(provider.AccessToken) > 0 && len(provider.InternalRoomID) > 0
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	config := provider.getConfigForGroup(endpoint.Group)
+	if config.ServerURL == "" {
+		config.ServerURL = defaultHomeserverURL
+	}
+	// The Matrix endpoint requires a unique transaction ID for each event sent
+	txnId := randStringBytes(24)
+	request, err := http.NewRequest(
+		http.MethodPut,
+		fmt.Sprintf("%s/_matrix/client/v3/rooms/%s/send/m.room.message/%s?access_token=%s",
+			config.ServerURL,
+			url.PathEscape(config.InternalRoomID),
+			txnId,
+			url.QueryEscape(config.AccessToken),
+		),
+		buffer,
+	)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	MsgType       string `json:"msgtype"`
+	Format        string `json:"format"`
+	Body          string `json:"body"`
+	FormattedBody string `json:"formatted_body"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	body, _ := json.Marshal(Body{
+		MsgType:       "m.text",
+		Format:        "org.matrix.custom.html",
+		Body:          buildPlaintextMessageBody(endpoint, alert, result, resolved),
+		FormattedBody: buildHTMLMessageBody(endpoint, alert, result, resolved),
+	})
+	return body
+}
+
+// buildPlaintextMessageBody builds the message body in plaintext to include in request
+func buildPlaintextMessageBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) string {
+	var message, results string
+	if resolved {
+		message = fmt.Sprintf("An alert for `%s` has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for `%s` has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✓"
+		} else {
+			prefix = "✕"
+		}
+		results += fmt.Sprintf("\n%s - %s", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = "\n" + alertDescription
+	}
+	return fmt.Sprintf("%s%s\n%s", message, description, results)
+}
+
+// buildHTMLMessageBody builds the message body in HTML to include in request
+func buildHTMLMessageBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) string {
+	var message, results string
+	if resolved {
+		message = fmt.Sprintf("An alert for <code>%s</code> has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for <code>%s</code> has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		results += fmt.Sprintf("<li>%s - <code>%s</code></li>", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = fmt.Sprintf("\n<blockquote>%s</blockquote>", alertDescription)
+	}
+	return fmt.Sprintf("<h3>%s</h3>%s\n<h5>Condition results</h5><ul>%s</ul>", message, description, results)
+}
+
+// getConfigForGroup returns the appropriate configuration for a given group
+func (provider *AlertProvider) getConfigForGroup(group string) MatrixProviderConfig {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.MatrixProviderConfig
+			}
+		}
+	}
+	return provider.MatrixProviderConfig
+}
+
+func randStringBytes(n int) string {
+	// All the compatible characters to use in a transaction ID
+	const availableCharacterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+	b := make([]byte, n)
+	rand.Seed(time.Now().UnixNano())
+	for i := range b {
+		b[i] = availableCharacterBytes[rand.Intn(len(availableCharacterBytes))]
+	}
+	return string(b)
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/matrix/matrix_test.go

@@ -0,0 +1,331 @@
+package matrix
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
+)
+
+func TestAlertProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{
+		MatrixProviderConfig: MatrixProviderConfig{
+			AccessToken:    "",
+			InternalRoomID: "",
+		},
+	}
+	if invalidProvider.IsValid() {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{
+		MatrixProviderConfig: MatrixProviderConfig{
+			AccessToken:    "1",
+			InternalRoomID: "!a:example.com",
+		},
+	}
+	if !validProvider.IsValid() {
+		t.Error("provider should've been valid")
+	}
+	validProviderWithHomeserver := AlertProvider{
+		MatrixProviderConfig: MatrixProviderConfig{
+			ServerURL:      "https://example.com",
+			AccessToken:    "1",
+			InternalRoomID: "!a:example.com",
+		},
+	}
+	if !validProviderWithHomeserver.IsValid() {
+		t.Error("provider with homeserver should've been valid")
+	}
+}
+
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				Group: "",
+				MatrixProviderConfig: MatrixProviderConfig{
+					AccessToken:    "",
+					InternalRoomID: "",
+				},
+			},
+		},
+	}
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				Group: "group",
+				MatrixProviderConfig: MatrixProviderConfig{
+					AccessToken:    "",
+					InternalRoomID: "",
+				},
+			},
+		},
+	}
+	if providerWithInvalidOverrideTo.IsValid() {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		MatrixProviderConfig: MatrixProviderConfig{
+			AccessToken:    "1",
+			InternalRoomID: "!a:example.com",
+		},
+		Overrides: []Override{
+			{
+				Group: "group",
+				MatrixProviderConfig: MatrixProviderConfig{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"msgtype\":\"m.text\",\"format\":\"org.matrix.custom.html\",\"body\":\"An alert for `endpoint-name` has been triggered due to having failed 3 time(s) in a row\\ndescription-1\\n\\n✕ - [CONNECTED] == true\\n✕ - [STATUS] == 200\",\"formatted_body\":\"\\u003ch3\\u003eAn alert for \\u003ccode\\u003eendpoint-name\\u003c/code\\u003e has been triggered due to having failed 3 time(s) in a row\\u003c/h3\\u003e\\n\\u003cblockquote\\u003edescription-1\\u003c/blockquote\\u003e\\n\\u003ch5\\u003eCondition results\\u003c/h5\\u003e\\u003cul\\u003e\\u003cli\\u003e❌ - \\u003ccode\\u003e[CONNECTED] == true\\u003c/code\\u003e\\u003c/li\\u003e\\u003cli\\u003e❌ - \\u003ccode\\u003e[STATUS] == 200\\u003c/code\\u003e\\u003c/li\\u003e\\u003c/ul\\u003e\"}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"msgtype\":\"m.text\",\"format\":\"org.matrix.custom.html\",\"body\":\"An alert for `endpoint-name` has been resolved after passing successfully 5 time(s) in a row\\ndescription-2\\n\\n✓ - [CONNECTED] == true\\n✓ - [STATUS] == 200\",\"formatted_body\":\"\\u003ch3\\u003eAn alert for \\u003ccode\\u003eendpoint-name\\u003c/code\\u003e has been resolved after passing successfully 5 time(s) in a row\\u003c/h3\\u003e\\n\\u003cblockquote\\u003edescription-2\\u003c/blockquote\\u003e\\n\\u003ch5\\u003eCondition results\\u003c/h5\\u003e\\u003cul\\u003e\\u003cli\\u003e✅ - \\u003ccode\\u003e[CONNECTED] == true\\u003c/code\\u003e\\u003c/li\\u003e\\u003cli\\u003e✅ - \\u003ccode\\u003e[STATUS] == 200\\u003c/code\\u003e\\u003c/li\\u003e\\u003c/ul\\u003e\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getConfigForGroup(t *testing.T) {
+	tests := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput MatrixProviderConfig
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				MatrixProviderConfig: MatrixProviderConfig{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: nil,
+			},
+			InputGroup: "",
+			ExpectedOutput: MatrixProviderConfig{
+				ServerURL:      "https://example.com",
+				AccessToken:    "1",
+				InternalRoomID: "!a:example.com",
+			},
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				MatrixProviderConfig: MatrixProviderConfig{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: nil,
+			},
+			InputGroup: "group",
+			ExpectedOutput: MatrixProviderConfig{
+				ServerURL:      "https://example.com",
+				AccessToken:    "1",
+				InternalRoomID: "!a:example.com",
+			},
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				MatrixProviderConfig: MatrixProviderConfig{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: []Override{
+					{
+						Group: "group",
+						MatrixProviderConfig: MatrixProviderConfig{
+							ServerURL:      "https://example01.com",
+							AccessToken:    "12",
+							InternalRoomID: "!a:example01.com",
+						},
+					},
+				},
+			},
+			InputGroup: "",
+			ExpectedOutput: MatrixProviderConfig{
+				ServerURL:      "https://example.com",
+				AccessToken:    "1",
+				InternalRoomID: "!a:example.com",
+			},
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				MatrixProviderConfig: MatrixProviderConfig{
+					ServerURL:      "https://example.com",
+					AccessToken:    "1",
+					InternalRoomID: "!a:example.com",
+				},
+				Overrides: []Override{
+					{
+						Group: "group",
+						MatrixProviderConfig: MatrixProviderConfig{
+							ServerURL:      "https://example01.com",
+							AccessToken:    "12",
+							InternalRoomID: "!a:example01.com",
+						},
+					},
+				},
+			},
+			InputGroup: "group",
+			ExpectedOutput: MatrixProviderConfig{
+				ServerURL:      "https://example01.com",
+				AccessToken:    "12",
+				InternalRoomID: "!a:example01.com",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			if got := tt.Provider.getConfigForGroup(tt.InputGroup); got != tt.ExpectedOutput {
+				t.Errorf("AlertProvider.getConfigForGroup() = %v, want %v", got, tt.ExpectedOutput)
+			}
+		})
+	}
+}

alerting/provider/mattermost/mattermost.go

@@ -1,36 +1,106 @@
 package mattermost
 
 import (
+	"bytes"
+	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 
-	"github.com/TwinProduction/gatus/alerting/provider/custom"
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
 )
 
 // AlertProvider is the configuration necessary for sending an alert using Mattermost
 type AlertProvider struct {
 	WebhookURL string `yaml:"webhook-url"`
-	Insecure   bool   `yaml:"insecure,omitempty"`
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group      string `yaml:"group"`
+	WebhookURL string `yaml:"webhook-url"`
 }
 
 // IsValid returns whether the provider's configuration is valid
 func (provider *AlertProvider) IsValid() bool {
+	if provider.ClientConfig == nil {
+		provider.ClientConfig = client.GetDefaultConfig()
+	}
+	if provider.Overrides != nil {
+		registeredGroups := make(map[string]bool)
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
 	return len(provider.WebhookURL) > 0
 }
 
-// ToCustomAlertProvider converts the provider into a custom.AlertProvider
-func (provider *AlertProvider) ToCustomAlertProvider(service *core.Service, alert *core.Alert, result *core.Result, resolved bool) *custom.AlertProvider {
-	var message string
-	var color string
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer([]byte(provider.buildRequestBody(endpoint, alert, result, resolved)))
+	request, err := http.NewRequest(http.MethodPost, provider.getWebhookURLForGroup(endpoint.Group), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(provider.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Text        string       `json:"text"`
+	Username    string       `json:"username"`
+	IconURL     string       `json:"icon_url"`
+	Attachments []Attachment `json:"attachments"`
+}
+
+type Attachment struct {
+	Title    string  `json:"title"`
+	Fallback string  `json:"fallback"`
+	Text     string  `json:"text"`
+	Short    bool    `json:"short"`
+	Color    string  `json:"color"`
+	Fields   []Field `json:"fields"`
+}
+
+type Field struct {
+	Title string `json:"title"`
+	Value string `json:"value"`
+	Short bool   `json:"short"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	var message, color, results string
 	if resolved {
-		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", service.Name, alert.SuccessThreshold)
+		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
 		color = "#36A64F"
 	} else {
-		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", service.Name, alert.FailureThreshold)
+		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
 		color = "#DD0000"
 	}
-	var results string
 	for _, conditionResult := range result.ConditionResults {
 		var prefix string
 		if conditionResult.Success {
@@ -40,36 +110,47 @@ func (provider *AlertProvider) ToCustomAlertProvider(service *core.Service, aler
 		}
 		results += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
 	}
-	return &custom.AlertProvider{
-		URL:      provider.WebhookURL,
-		Method:   http.MethodPost,
-		Insecure: provider.Insecure,
-		Body: fmt.Sprintf(`{
-  "text": "",
-  "username": "gatus",
-  "icon_url": "https://raw.githubusercontent.com/TwinProduction/gatus/master/static/logo.png",
-  "attachments": [
-    {
-      "title": ":rescue_worker_helmet: Gatus",
-      "fallback": "Gatus - %s",
-      "text": "%s:\n> %s",
-      "short": false,
-      "color": "%s",
-      "fields": [
-        {
-          "title": "URL",
-          "value": "%s",
-          "short": false
-        },
-        {
-          "title": "Condition results",
-          "value": "%s",
-          "short": false
-        }
-      ]
-    }
-  ]
-}`, message, message, alert.Description, color, service.URL, results),
-		Headers: map[string]string{"Content-Type": "application/json"},
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
 	}
+	body, _ := json.Marshal(Body{
+		Text:     "",
+		Username: "gatus",
+		IconURL:  "https://raw.githubusercontent.com/TwiN/gatus/master/.github/assets/logo.png",
+		Attachments: []Attachment{
+			{
+				Title:    ":helmet_with_white_cross: Gatus",
+				Fallback: "Gatus - " + message,
+				Text:     message + description,
+				Short:    false,
+				Color:    color,
+				Fields: []Field{
+					{
+						Title: "Condition results",
+						Value: results,
+						Short: false,
+					},
+				},
+			},
+		},
+	})
+	return body
+}
+
+// getWebhookURLForGroup returns the appropriate Webhook URL integration to for a given group
+func (provider *AlertProvider) getWebhookURLForGroup(group string) string {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.WebhookURL
+			}
+		}
+	}
+	return provider.WebhookURL
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
 }

alerting/provider/mattermost/mattermost_test.go

@@ -1,10 +1,14 @@
 package mattermost
 
 import (
-	"strings"
+	"encoding/json"
+	"net/http"
 	"testing"
 
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
 )
 
 func TestAlertProvider_IsValid(t *testing.T) {
@@ -18,24 +22,241 @@ func TestAlertProvider_IsValid(t *testing.T) {
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithResolvedAlert(t *testing.T) {
-	provider := AlertProvider{WebhookURL: "http://example.com"}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{ConditionResults: []*core.ConditionResult{{Condition: "SUCCESSFUL_CONDITION", Success: true}}}, true)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "",
+			},
+		},
 	}
-	if !strings.Contains(customAlertProvider.Body, "resolved") {
-		t.Error("customAlertProvider.Body should've contained the substring resolved")
+
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+
+	providerWithInvalidOverrideWebHookUrl := AlertProvider{
+		Overrides: []Override{
+			{
+
+				WebhookURL: "",
+				Group:      "group",
+			},
+		},
+	}
+	if providerWithInvalidOverrideWebHookUrl.IsValid() {
+		t.Error("provider WebHookURL shoudn't have been valid")
+	}
+
+	providerWithValidOverride := AlertProvider{
+		WebhookURL: "http://example.com",
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "group",
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithTriggeredAlert(t *testing.T) {
-	provider := AlertProvider{WebhookURL: "http://example.com"}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{ConditionResults: []*core.ConditionResult{{Condition: "UNSUCCESSFUL_CONDITION", Success: false}}}, false)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
 	}
-	if !strings.Contains(customAlertProvider.Body, "triggered") {
-		t.Error("customAlertProvider.Body should've contained the substring triggered")
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"text\":\"\",\"username\":\"gatus\",\"icon_url\":\"https://raw.githubusercontent.com/TwiN/gatus/master/.github/assets/logo.png\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"fallback\":\"Gatus - An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row\",\"text\":\"An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"short\":false,\"color\":\"#DD0000\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"text\":\"\",\"username\":\"gatus\",\"icon_url\":\"https://raw.githubusercontent.com/TwiN/gatus/master/.github/assets/logo.png\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"fallback\":\"Gatus - An alert for *endpoint-name* has been resolved after passing successfully 5 time(s) in a row\",\"text\":\"An alert for *endpoint-name* has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"short\":false,\"color\":\"#36A64F\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getWebhookURLForGroup(t *testing.T) {
+	tests := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput string
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example01.com",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			if got := tt.Provider.getWebhookURLForGroup(tt.InputGroup); got != tt.ExpectedOutput {
+				t.Errorf("AlertProvider.getToForGroup() = %v, want %v", got, tt.ExpectedOutput)
+			}
+		})
 	}
 }

alerting/provider/messagebird/messagebird.go

@@ -1,11 +1,15 @@
 package messagebird
 
 import (
+	"bytes"
+	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 
-	"github.com/TwinProduction/gatus/alerting/provider/custom"
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
 )
 
 const (
@@ -17,6 +21,9 @@ type AlertProvider struct {
 	AccessKey  string `yaml:"access-key"`
 	Originator string `yaml:"originator"`
 	Recipients string `yaml:"recipients"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
 }
 
 // IsValid returns whether the provider's configuration is valid
@@ -24,27 +31,51 @@ func (provider *AlertProvider) IsValid() bool {
 	return len(provider.AccessKey) > 0 && len(provider.Originator) > 0 && len(provider.Recipients) > 0
 }
 
-// ToCustomAlertProvider converts the provider into a custom.AlertProvider
-// Reference doc for messagebird https://developers.messagebird.com/api/sms-messaging/#send-outbound-sms
-func (provider *AlertProvider) ToCustomAlertProvider(service *core.Service, alert *core.Alert, _ *core.Result, resolved bool) *custom.AlertProvider {
+// Send an alert using the provider
+// Reference doc for messagebird: https://developers.messagebird.com/api/sms-messaging/#send-outbound-sms
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, restAPIURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	request.Header.Set("Authorization", fmt.Sprintf("AccessKey %s", provider.AccessKey))
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Originator string `json:"originator"`
+	Recipients string `json:"recipients"`
+	Body       string `json:"body"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
 	var message string
 	if resolved {
-		message = fmt.Sprintf("RESOLVED: %s - %s", service.Name, alert.Description)
+		message = fmt.Sprintf("RESOLVED: %s - %s", endpoint.DisplayName(), alert.GetDescription())
 	} else {
-		message = fmt.Sprintf("TRIGGERED: %s - %s", service.Name, alert.Description)
-	}
-
-	return &custom.AlertProvider{
-		URL:    restAPIURL,
-		Method: http.MethodPost,
-		Body: fmt.Sprintf(`{
-  "originator": "%s",
-  "recipients": "%s",
-  "body": "%s"
-}`, provider.Originator, provider.Recipients, message),
-		Headers: map[string]string{
-			"Content-Type":  "application/json",
-			"Authorization": fmt.Sprintf("AccessKey %s", provider.AccessKey),
-		},
+		message = fmt.Sprintf("TRIGGERED: %s - %s", endpoint.DisplayName(), alert.GetDescription())
 	}
+	body, _ := json.Marshal(Body{
+		Originator: provider.Originator,
+		Recipients: provider.Recipients,
+		Body:       message,
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
 }

alerting/provider/messagebird/messagebird_test.go

@@ -1,10 +1,14 @@
 package messagebird
 
 import (
-	"strings"
+	"encoding/json"
+	"net/http"
 	"testing"
 
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
 )
 
 func TestMessagebirdAlertProvider_IsValid(t *testing.T) {
@@ -22,32 +26,137 @@ func TestMessagebirdAlertProvider_IsValid(t *testing.T) {
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithResolvedAlert(t *testing.T) {
-	provider := AlertProvider{
-		AccessKey:  "1",
-		Originator: "1",
-		Recipients: "1",
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
 	}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, true)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
-	}
-	if !strings.Contains(customAlertProvider.Body, "RESOLVED") {
-		t.Error("customAlertProvider.Body should've contained the substring RESOLVED")
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithTriggeredAlert(t *testing.T) {
-	provider := AlertProvider{
-		AccessKey:  "1",
-		Originator: "1",
-		Recipients: "1",
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{AccessKey: "1", Originator: "2", Recipients: "3"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"originator\":\"2\",\"recipients\":\"3\",\"body\":\"TRIGGERED: endpoint-name - description-1\"}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{AccessKey: "4", Originator: "5", Recipients: "6"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"originator\":\"5\",\"recipients\":\"6\",\"body\":\"RESOLVED: endpoint-name - description-2\"}",
+		},
 	}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, false)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
-	}
-	if !strings.Contains(customAlertProvider.Body, "TRIGGERED") {
-		t.Error("customAlertProvider.Body should've contained the substring TRIGGERED")
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal([]byte(body), &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
 	}
 }

alerting/provider/ntfy/ntfy.go

@@ -0,0 +1,95 @@
+package ntfy
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+const (
+	DefaultURL      = "https://ntfy.sh"
+	DefaultPriority = 3
+)
+
+// AlertProvider is the configuration necessary for sending an alert using Slack
+type AlertProvider struct {
+	Topic    string `yaml:"topic"`
+	URL      string `yaml:"url,omitempty"`      // Defaults to DefaultURL
+	Priority int    `yaml:"priority,omitempty"` // Defaults to DefaultPriority
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	if len(provider.URL) == 0 {
+		provider.URL = DefaultURL
+	}
+	if provider.Priority == 0 {
+		provider.Priority = DefaultPriority
+	}
+	return len(provider.URL) > 0 && len(provider.Topic) > 0 && provider.Priority > 0 && provider.Priority < 6
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, provider.URL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Topic    string   `json:"topic"`
+	Title    string   `json:"title"`
+	Message  string   `json:"message"`
+	Tags     []string `json:"tags"`
+	Priority int      `json:"priority"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	var message, tag string
+	if len(alert.GetDescription()) > 0 {
+		message = endpoint.DisplayName() + " - " + alert.GetDescription()
+	} else {
+		message = endpoint.DisplayName()
+	}
+	if resolved {
+		tag = "white_check_mark"
+	} else {
+		tag = "x"
+	}
+	body, _ := json.Marshal(Body{
+		Topic:    provider.Topic,
+		Title:    "Gatus",
+		Message:  message,
+		Tags:     []string{tag},
+		Priority: provider.Priority,
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/ntfy/ntfy_test.go

@@ -0,0 +1,104 @@
+package ntfy
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+func TestAlertDefaultProvider_IsValid(t *testing.T) {
+	scenarios := []struct {
+		name     string
+		provider AlertProvider
+		expected bool
+	}{
+		{
+			name:     "valid",
+			provider: AlertProvider{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+			expected: true,
+		},
+		{
+			name:     "no-url-should-use-default-value",
+			provider: AlertProvider{Topic: "example", Priority: 1},
+			expected: true,
+		},
+		{
+			name:     "invalid-topic",
+			provider: AlertProvider{URL: "https://ntfy.sh", Topic: "", Priority: 1},
+			expected: false,
+		},
+		{
+			name:     "invalid-priority-too-high",
+			provider: AlertProvider{URL: "https://ntfy.sh", Topic: "example", Priority: 6},
+			expected: false,
+		},
+		{
+			name:     "invalid-priority-too-low",
+			provider: AlertProvider{URL: "https://ntfy.sh", Topic: "example", Priority: -1},
+			expected: false,
+		},
+		{
+			name:     "no-priority-should-use-default-value",
+			provider: AlertProvider{URL: "https://ntfy.sh", Topic: "example"},
+			expected: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			if scenario.provider.IsValid() != scenario.expected {
+				t.Errorf("expected %t, got %t", scenario.expected, scenario.provider.IsValid())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{URL: "https://ntfy.sh", Topic: "example", Priority: 1},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"topic\":\"example\",\"title\":\"Gatus\",\"message\":\"endpoint-name - description-1\",\"tags\":[\"x\"],\"priority\":1}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{URL: "https://ntfy.sh", Topic: "example", Priority: 2},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"topic\":\"example\",\"title\":\"Gatus\",\"message\":\"endpoint-name - description-2\",\"tags\":[\"white_check_mark\"],\"priority\":2}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}

alerting/provider/opsgenie/opsgenie.go

@@ -0,0 +1,239 @@
+package opsgenie
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"strconv"
+	"strings"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+const (
+	restAPI = "https://api.opsgenie.com/v2/alerts"
+)
+
+type AlertProvider struct {
+	// APIKey to use for
+	APIKey string `yaml:"api-key"`
+
+	// Priority to be used in Opsgenie alert payload
+	//
+	// default: P1
+	Priority string `yaml:"priority"`
+
+	// Source define source to be used in Opsgenie alert payload
+	//
+	// default: gatus
+	Source string `yaml:"source"`
+
+	// EntityPrefix is a prefix to be used in entity argument in Opsgenie alert payload
+	//
+	// default: gatus-
+	EntityPrefix string `yaml:"entity-prefix"`
+
+	//AliasPrefix is a prefix to be used in alias argument in Opsgenie alert payload
+	//
+	// default: gatus-healthcheck-
+	AliasPrefix string `yaml:"alias-prefix"`
+
+	// Tags to be used in Opsgenie alert payload
+	//
+	// default: []
+	Tags []string `yaml:"tags"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	return len(provider.APIKey) > 0
+}
+
+// Send an alert using the provider
+//
+// Relevant: https://docs.opsgenie.com/docs/alert-api
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	err := provider.createAlert(endpoint, alert, result, resolved)
+	if err != nil {
+		return err
+	}
+	if resolved {
+		err = provider.closeAlert(endpoint, alert)
+		if err != nil {
+			return err
+		}
+	}
+	if alert.IsSendingOnResolved() {
+		if resolved {
+			// The alert has been resolved and there's no error, so we can clear the alert's ResolveKey
+			alert.ResolveKey = ""
+		} else {
+			alert.ResolveKey = provider.alias(buildKey(endpoint))
+		}
+	}
+	return nil
+}
+
+func (provider *AlertProvider) createAlert(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	payload := provider.buildCreateRequestBody(endpoint, alert, result, resolved)
+	return provider.sendRequest(restAPI, http.MethodPost, payload)
+}
+
+func (provider *AlertProvider) closeAlert(endpoint *core.Endpoint, alert *alert.Alert) error {
+	payload := provider.buildCloseRequestBody(endpoint, alert)
+	url := restAPI + "/" + provider.alias(buildKey(endpoint)) + "/close?identifierType=alias"
+	return provider.sendRequest(url, http.MethodPost, payload)
+}
+
+func (provider *AlertProvider) sendRequest(url, method string, payload interface{}) error {
+	body, err := json.Marshal(payload)
+	if err != nil {
+		return fmt.Errorf("error build alert with payload %v: %w", payload, err)
+	}
+	request, err := http.NewRequest(method, url, bytes.NewBuffer(body))
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	request.Header.Set("Authorization", "GenieKey "+provider.APIKey)
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		rBody, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(rBody))
+	}
+	return nil
+}
+
+func (provider *AlertProvider) buildCreateRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) alertCreateRequest {
+	var message, description, results string
+	if resolved {
+		message = fmt.Sprintf("RESOLVED: %s - %s", endpoint.Name, alert.GetDescription())
+		description = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
+	} else {
+		message = fmt.Sprintf("%s - %s", endpoint.Name, alert.GetDescription())
+		description = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
+	}
+	if endpoint.Group != "" {
+		message = fmt.Sprintf("[%s] %s", endpoint.Group, message)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "▣"
+		} else {
+			prefix = "▢"
+		}
+		results += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+	}
+	description = description + "\n" + results
+	key := buildKey(endpoint)
+	details := map[string]string{
+		"endpoint:url":    endpoint.URL,
+		"endpoint:group":  endpoint.Group,
+		"result:hostname": result.Hostname,
+		"result:ip":       result.IP,
+		"result:dns_code": result.DNSRCode,
+		"result:errors":   strings.Join(result.Errors, ","),
+	}
+	for k, v := range details {
+		if v == "" {
+			delete(details, k)
+		}
+	}
+	if result.HTTPStatus > 0 {
+		details["result:http_status"] = strconv.Itoa(result.HTTPStatus)
+	}
+	return alertCreateRequest{
+		Message:     message,
+		Description: description,
+		Source:      provider.source(),
+		Priority:    provider.priority(),
+		Alias:       provider.alias(key),
+		Entity:      provider.entity(key),
+		Tags:        provider.Tags,
+		Details:     details,
+	}
+}
+
+func (provider *AlertProvider) buildCloseRequestBody(endpoint *core.Endpoint, alert *alert.Alert) alertCloseRequest {
+	return alertCloseRequest{
+		Source: buildKey(endpoint),
+		Note:   fmt.Sprintf("RESOLVED: %s - %s", endpoint.Name, alert.GetDescription()),
+	}
+}
+
+func (provider *AlertProvider) source() string {
+	source := provider.Source
+	if source == "" {
+		return "gatus"
+	}
+	return source
+}
+
+func (provider *AlertProvider) alias(key string) string {
+	alias := provider.AliasPrefix
+	if alias == "" {
+		alias = "gatus-healthcheck-"
+	}
+	return alias + key
+}
+
+func (provider *AlertProvider) entity(key string) string {
+	alias := provider.EntityPrefix
+	if alias == "" {
+		alias = "gatus-"
+	}
+	return alias + key
+}
+
+func (provider *AlertProvider) priority() string {
+	priority := provider.Priority
+	if priority == "" {
+		return "P1"
+	}
+	return priority
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+func buildKey(endpoint *core.Endpoint) string {
+	name := toKebabCase(endpoint.Name)
+	if endpoint.Group == "" {
+		return name
+	}
+	return toKebabCase(endpoint.Group) + "-" + name
+}
+
+func toKebabCase(val string) string {
+	return strings.ToLower(strings.ReplaceAll(val, " ", "-"))
+}
+
+type alertCreateRequest struct {
+	Message     string            `json:"message"`
+	Priority    string            `json:"priority"`
+	Source      string            `json:"source"`
+	Entity      string            `json:"entity"`
+	Alias       string            `json:"alias"`
+	Description string            `json:"description"`
+	Tags        []string          `json:"tags,omitempty"`
+	Details     map[string]string `json:"details"`
+}
+
+type alertCloseRequest struct {
+	Source string `json:"source"`
+	Note   string `json:"note"`
+}

alerting/provider/opsgenie/opsgenie_test.go

@@ -0,0 +1,319 @@
+package opsgenie
+
+import (
+	"net/http"
+	"reflect"
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
+)
+
+func TestAlertProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{APIKey: ""}
+	if invalidProvider.IsValid() {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{APIKey: "00000000-0000-0000-0000-000000000000"}
+	if !validProvider.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	description := "my bad alert description"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:          "triggered",
+			Provider:      AlertProvider{},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 1, FailureThreshold: 1},
+			Resolved:      false,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "triggered-error",
+			Provider:      AlertProvider{},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      false,
+			ExpectedError: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "resolved",
+			Provider:      AlertProvider{},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+		},
+		{
+			Name:          "resolved-error",
+			Provider:      AlertProvider{},
+			Alert:         alert.Alert{Description: &description, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:      true,
+			ExpectedError: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+		},
+	}
+
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildCreateRequestBody(t *testing.T) {
+	t.Parallel()
+	description := "alert description"
+	scenarios := []struct {
+		Name     string
+		Provider *AlertProvider
+		Alert    *alert.Alert
+		Endpoint *core.Endpoint
+		Result   *core.Result
+		Resolved bool
+		want     alertCreateRequest
+	}{
+		{
+			Name:     "missing all params (unresolved)",
+			Provider: &AlertProvider{},
+			Alert:    &alert.Alert{},
+			Endpoint: &core.Endpoint{},
+			Result:   &core.Result{},
+			Resolved: false,
+			want: alertCreateRequest{
+				Message:     " - ",
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-",
+				Alias:       "gatus-healthcheck-",
+				Description: "An alert for ** has been triggered due to having failed 0 time(s) in a row\n",
+				Tags:        nil,
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name:     "missing all params (resolved)",
+			Provider: &AlertProvider{},
+			Alert:    &alert.Alert{},
+			Endpoint: &core.Endpoint{},
+			Result:   &core.Result{},
+			Resolved: true,
+			want: alertCreateRequest{
+				Message:     "RESOLVED:  - ",
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-",
+				Alias:       "gatus-healthcheck-",
+				Description: "An alert for ** has been resolved after passing successfully 0 time(s) in a row\n",
+				Tags:        nil,
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name:     "with default options (unresolved)",
+			Provider: &AlertProvider{},
+			Alert: &alert.Alert{
+				Description:      &description,
+				FailureThreshold: 3,
+			},
+			Endpoint: &core.Endpoint{
+				Name: "my super app",
+			},
+			Result: &core.Result{
+				ConditionResults: []*core.ConditionResult{
+					{
+						Condition: "[STATUS] == 200",
+						Success:   true,
+					},
+					{
+						Condition: "[BODY] == OK",
+						Success:   false,
+					},
+				},
+			},
+			Resolved: false,
+			want: alertCreateRequest{
+				Message:     "my super app - " + description,
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-my-super-app",
+				Alias:       "gatus-healthcheck-my-super-app",
+				Description: "An alert for *my super app* has been triggered due to having failed 3 time(s) in a row\n▣ - `[STATUS] == 200`\n▢ - `[BODY] == OK`\n",
+				Tags:        nil,
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name: "with custom options (resolved)",
+			Provider: &AlertProvider{
+				Priority:     "P5",
+				EntityPrefix: "oompa-",
+				AliasPrefix:  "loompa-",
+				Source:       "gatus-hc",
+				Tags:         []string{"do-ba-dee-doo"},
+			},
+			Alert: &alert.Alert{
+				Description:      &description,
+				SuccessThreshold: 4,
+			},
+			Endpoint: &core.Endpoint{
+				Name: "my mega app",
+			},
+			Result: &core.Result{
+				ConditionResults: []*core.ConditionResult{
+					{
+						Condition: "[STATUS] == 200",
+						Success:   true,
+					},
+				},
+			},
+			Resolved: true,
+			want: alertCreateRequest{
+				Message:     "RESOLVED: my mega app - " + description,
+				Priority:    "P5",
+				Source:      "gatus-hc",
+				Entity:      "oompa-my-mega-app",
+				Alias:       "loompa-my-mega-app",
+				Description: "An alert for *my mega app* has been resolved after passing successfully 4 time(s) in a row\n▣ - `[STATUS] == 200`\n",
+				Tags:        []string{"do-ba-dee-doo"},
+				Details:     map[string]string{},
+			},
+		},
+		{
+			Name: "with default options and details (unresolved)",
+			Provider: &AlertProvider{
+				Tags: []string{"foo"},
+			},
+			Alert: &alert.Alert{
+				Description:      &description,
+				FailureThreshold: 6,
+			},
+			Endpoint: &core.Endpoint{
+				Name:  "my app",
+				Group: "end game",
+				URL:   "https://my.go/app",
+			},
+			Result: &core.Result{
+				HTTPStatus: 400,
+				Hostname:   "my.go",
+				Errors:     []string{"error 01", "error 02"},
+				Success:    false,
+				ConditionResults: []*core.ConditionResult{
+					{
+						Condition: "[STATUS] == 200",
+						Success:   false,
+					},
+				},
+			},
+			Resolved: false,
+			want: alertCreateRequest{
+				Message:     "[end game] my app - " + description,
+				Priority:    "P1",
+				Source:      "gatus",
+				Entity:      "gatus-end-game-my-app",
+				Alias:       "gatus-healthcheck-end-game-my-app",
+				Description: "An alert for *end game/my app* has been triggered due to having failed 6 time(s) in a row\n▢ - `[STATUS] == 200`\n",
+				Tags:        []string{"foo"},
+				Details: map[string]string{
+					"endpoint:url":       "https://my.go/app",
+					"endpoint:group":     "end game",
+					"result:hostname":    "my.go",
+					"result:errors":      "error 01,error 02",
+					"result:http_status": "400",
+				},
+			},
+		},
+	}
+	for _, scenario := range scenarios {
+		actual := scenario
+		t.Run(actual.Name, func(t *testing.T) {
+			if got := actual.Provider.buildCreateRequestBody(actual.Endpoint, actual.Alert, actual.Result, actual.Resolved); !reflect.DeepEqual(got, actual.want) {
+				t.Errorf("buildCreateRequestBody() = %v, want %v", got, actual.want)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildCloseRequestBody(t *testing.T) {
+	t.Parallel()
+	description := "alert description"
+	scenarios := []struct {
+		Name     string
+		Provider *AlertProvider
+		Alert    *alert.Alert
+		Endpoint *core.Endpoint
+		want     alertCloseRequest
+	}{
+		{
+			Name:     "Missing all values",
+			Provider: &AlertProvider{},
+			Alert:    &alert.Alert{},
+			Endpoint: &core.Endpoint{},
+			want: alertCloseRequest{
+				Source: "",
+				Note:   "RESOLVED:  - ",
+			},
+		},
+		{
+			Name:     "Basic values",
+			Provider: &AlertProvider{},
+			Alert: &alert.Alert{
+				Description: &description,
+			},
+			Endpoint: &core.Endpoint{
+				Name: "endpoint name",
+			},
+			want: alertCloseRequest{
+				Source: "endpoint-name",
+				Note:   "RESOLVED: endpoint name - alert description",
+			},
+		},
+	}
+
+	for _, scenario := range scenarios {
+		actual := scenario
+		t.Run(actual.Name, func(t *testing.T) {
+			if got := actual.Provider.buildCloseRequestBody(actual.Endpoint, actual.Alert); !reflect.DeepEqual(got, actual.want) {
+				t.Errorf("buildCloseRequestBody() = %v, want %v", got, actual.want)
+			}
+		})
+	}
+}

alerting/provider/pagerduty/pagerduty.go

@@ -1,52 +1,149 @@
 package pagerduty
 
 import (
+	"bytes"
+	"encoding/json"
 	"fmt"
+	"io"
+	"log"
 	"net/http"
 
-	"github.com/TwinProduction/gatus/alerting/provider/custom"
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+const (
+	restAPIURL = "https://events.pagerduty.com/v2/enqueue"
 )
 
 // AlertProvider is the configuration necessary for sending an alert using PagerDuty
 type AlertProvider struct {
 	IntegrationKey string `yaml:"integration-key"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group          string `yaml:"group"`
+	IntegrationKey string `yaml:"integration-key"`
 }
 
 // IsValid returns whether the provider's configuration is valid
 func (provider *AlertProvider) IsValid() bool {
-	return len(provider.IntegrationKey) == 32
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.IntegrationKey) != 32 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	// Either the default integration key has the right length, or there are overrides who are properly configured.
+	return len(provider.IntegrationKey) == 32 || len(provider.Overrides) != 0
 }
 
-// ToCustomAlertProvider converts the provider into a custom.AlertProvider
+// Send an alert using the provider
 //
-// relevant: https://developer.pagerduty.com/docs/events-api-v2/trigger-events/
-func (provider *AlertProvider) ToCustomAlertProvider(service *core.Service, alert *core.Alert, _ *core.Result, resolved bool) *custom.AlertProvider {
+// Relevant: https://developer.pagerduty.com/docs/events-api-v2/trigger-events/
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, restAPIURL, buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	if alert.IsSendingOnResolved() {
+		if resolved {
+			// The alert has been resolved and there's no error, so we can clear the alert's ResolveKey
+			alert.ResolveKey = ""
+		} else {
+			// We need to retrieve the resolve key from the response
+			body, err := io.ReadAll(response.Body)
+			var payload pagerDutyResponsePayload
+			if err = json.Unmarshal(body, &payload); err != nil {
+				// Silently fail. We don't want to create tons of alerts just because we failed to parse the body.
+				log.Printf("[pagerduty][Send] Ran into error unmarshaling pagerduty response: %s", err.Error())
+			} else {
+				alert.ResolveKey = payload.DedupKey
+			}
+		}
+	}
+	return nil
+}
+
+type Body struct {
+	RoutingKey  string  `json:"routing_key"`
+	DedupKey    string  `json:"dedup_key"`
+	EventAction string  `json:"event_action"`
+	Payload     Payload `json:"payload"`
+}
+
+type Payload struct {
+	Summary  string `json:"summary"`
+	Source   string `json:"source"`
+	Severity string `json:"severity"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
 	var message, eventAction, resolveKey string
 	if resolved {
-		message = fmt.Sprintf("RESOLVED: %s - %s", service.Name, alert.Description)
+		message = fmt.Sprintf("RESOLVED: %s - %s", endpoint.DisplayName(), alert.GetDescription())
 		eventAction = "resolve"
 		resolveKey = alert.ResolveKey
 	} else {
-		message = fmt.Sprintf("TRIGGERED: %s - %s", service.Name, alert.Description)
+		message = fmt.Sprintf("TRIGGERED: %s - %s", endpoint.DisplayName(), alert.GetDescription())
 		eventAction = "trigger"
 		resolveKey = ""
 	}
-	return &custom.AlertProvider{
-		URL:    "https://events.pagerduty.com/v2/enqueue",
-		Method: http.MethodPost,
-		Body: fmt.Sprintf(`{
-  "routing_key": "%s",
-  "dedup_key": "%s",
-  "event_action": "%s",
-  "payload": {
-    "summary": "%s",
-    "source": "%s",
-    "severity": "critical"
-  }
-}`, provider.IntegrationKey, resolveKey, eventAction, message, service.Name),
-		Headers: map[string]string{
-			"Content-Type": "application/json",
+	body, _ := json.Marshal(Body{
+		RoutingKey:  provider.getIntegrationKeyForGroup(endpoint.Group),
+		DedupKey:    resolveKey,
+		EventAction: eventAction,
+		Payload: Payload{
+			Summary:  message,
+			Source:   "Gatus",
+			Severity: "critical",
 		},
-	}
+	})
+	return body
+}
+
+// getIntegrationKeyForGroup returns the appropriate pagerduty integration key for a given group
+func (provider *AlertProvider) getIntegrationKeyForGroup(group string) string {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.IntegrationKey
+			}
+		}
+	}
+	return provider.IntegrationKey
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}
+
+type pagerDutyResponsePayload struct {
+	Status   string `json:"status"`
+	Message  string `json:"message"`
+	DedupKey string `json:"dedup_key"`
 }

alerting/provider/pagerduty/pagerduty_test.go

@@ -1,10 +1,14 @@
 package pagerduty
 
 import (
-	"strings"
+	"encoding/json"
+	"net/http"
 	"testing"
 
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
 )
 
 func TestAlertProvider_IsValid(t *testing.T) {
@@ -18,24 +22,225 @@ func TestAlertProvider_IsValid(t *testing.T) {
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithResolvedAlert(t *testing.T) {
-	provider := AlertProvider{IntegrationKey: "00000000000000000000000000000000"}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, true)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				IntegrationKey: "00000000000000000000000000000000",
+				Group:          "",
+			},
+		},
 	}
-	if !strings.Contains(customAlertProvider.Body, "RESOLVED") {
-		t.Error("customAlertProvider.Body should've contained the substring RESOLVED")
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideIntegrationKey := AlertProvider{
+		Overrides: []Override{
+			{
+				IntegrationKey: "",
+				Group:          "group",
+			},
+		},
+	}
+	if providerWithInvalidOverrideIntegrationKey.IsValid() {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		Overrides: []Override{
+			{
+				IntegrationKey: "00000000000000000000000000000000",
+				Group:          "group",
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithTriggeredAlert(t *testing.T) {
-	provider := AlertProvider{IntegrationKey: "00000000000000000000000000000000"}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, false)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
 	}
-	if !strings.Contains(customAlertProvider.Body, "TRIGGERED") {
-		t.Error("customAlertProvider.Body should've contained the substring TRIGGERED")
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	description := "test"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{IntegrationKey: "00000000000000000000000000000000"},
+			Alert:        alert.Alert{Description: &description},
+			Resolved:     false,
+			ExpectedBody: "{\"routing_key\":\"00000000000000000000000000000000\",\"dedup_key\":\"\",\"event_action\":\"trigger\",\"payload\":{\"summary\":\"TRIGGERED: endpoint-name - test\",\"source\":\"Gatus\",\"severity\":\"critical\"}}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{IntegrationKey: "00000000000000000000000000000000"},
+			Alert:        alert.Alert{Description: &description, ResolveKey: "key"},
+			Resolved:     true,
+			ExpectedBody: "{\"routing_key\":\"00000000000000000000000000000000\",\"dedup_key\":\"key\",\"event_action\":\"resolve\",\"payload\":{\"summary\":\"RESOLVED: endpoint-name - test\",\"source\":\"Gatus\",\"severity\":\"critical\"}}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(&core.Endpoint{Name: "endpoint-name"}, &scenario.Alert, &core.Result{}, scenario.Resolved)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_getIntegrationKeyForGroup(t *testing.T) {
+	scenarios := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput string
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				IntegrationKey: "00000000000000000000000000000001",
+				Overrides:      nil,
+			},
+			InputGroup:     "",
+			ExpectedOutput: "00000000000000000000000000000001",
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				IntegrationKey: "00000000000000000000000000000001",
+				Overrides:      nil,
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "00000000000000000000000000000001",
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				IntegrationKey: "00000000000000000000000000000001",
+				Overrides: []Override{
+					{
+						Group:          "group",
+						IntegrationKey: "00000000000000000000000000000002",
+					},
+				},
+			},
+			InputGroup:     "",
+			ExpectedOutput: "00000000000000000000000000000001",
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				IntegrationKey: "00000000000000000000000000000001",
+				Overrides: []Override{
+					{
+						Group:          "group",
+						IntegrationKey: "00000000000000000000000000000002",
+					},
+				},
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "00000000000000000000000000000002",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			if output := scenario.Provider.getIntegrationKeyForGroup(scenario.InputGroup); output != scenario.ExpectedOutput {
+				t.Errorf("expected %s, got %s", scenario.ExpectedOutput, output)
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
 	}
 }

alerting/provider/provider.go

@@ -1,13 +1,22 @@
 package provider
 
 import (
-	"github.com/TwinProduction/gatus/alerting/provider/custom"
-	"github.com/TwinProduction/gatus/alerting/provider/mattermost"
-	"github.com/TwinProduction/gatus/alerting/provider/messagebird"
-	"github.com/TwinProduction/gatus/alerting/provider/pagerduty"
-	"github.com/TwinProduction/gatus/alerting/provider/slack"
-	"github.com/TwinProduction/gatus/alerting/provider/twilio"
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/alerting/provider/custom"
+	"github.com/TwiN/gatus/v4/alerting/provider/discord"
+	"github.com/TwiN/gatus/v4/alerting/provider/email"
+	"github.com/TwiN/gatus/v4/alerting/provider/googlechat"
+	"github.com/TwiN/gatus/v4/alerting/provider/matrix"
+	"github.com/TwiN/gatus/v4/alerting/provider/mattermost"
+	"github.com/TwiN/gatus/v4/alerting/provider/messagebird"
+	"github.com/TwiN/gatus/v4/alerting/provider/ntfy"
+	"github.com/TwiN/gatus/v4/alerting/provider/opsgenie"
+	"github.com/TwiN/gatus/v4/alerting/provider/pagerduty"
+	"github.com/TwiN/gatus/v4/alerting/provider/slack"
+	"github.com/TwiN/gatus/v4/alerting/provider/teams"
+	"github.com/TwiN/gatus/v4/alerting/provider/telegram"
+	"github.com/TwiN/gatus/v4/alerting/provider/twilio"
+	"github.com/TwiN/gatus/v4/core"
 )
 
 // AlertProvider is the interface that each providers should implement
@@ -15,16 +24,49 @@ type AlertProvider interface {
 	// IsValid returns whether the provider's configuration is valid
 	IsValid() bool
 
-	// ToCustomAlertProvider converts the provider into a custom.AlertProvider
-	ToCustomAlertProvider(service *core.Service, alert *core.Alert, result *core.Result, resolved bool) *custom.AlertProvider
+	// GetDefaultAlert returns the provider's default alert configuration
+	GetDefaultAlert() *alert.Alert
+
+	// Send an alert using the provider
+	Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error
+}
+
+// ParseWithDefaultAlert parses an Endpoint alert by using the provider's default alert as a baseline
+func ParseWithDefaultAlert(providerDefaultAlert, endpointAlert *alert.Alert) {
+	if providerDefaultAlert == nil || endpointAlert == nil {
+		return
+	}
+	if endpointAlert.Enabled == nil {
+		endpointAlert.Enabled = providerDefaultAlert.Enabled
+	}
+	if endpointAlert.SendOnResolved == nil {
+		endpointAlert.SendOnResolved = providerDefaultAlert.SendOnResolved
+	}
+	if endpointAlert.Description == nil {
+		endpointAlert.Description = providerDefaultAlert.Description
+	}
+	if endpointAlert.FailureThreshold == 0 {
+		endpointAlert.FailureThreshold = providerDefaultAlert.FailureThreshold
+	}
+	if endpointAlert.SuccessThreshold == 0 {
+		endpointAlert.SuccessThreshold = providerDefaultAlert.SuccessThreshold
+	}
 }
 
 var (
 	// Validate interface implementation on compile
 	_ AlertProvider = (*custom.AlertProvider)(nil)
-	_ AlertProvider = (*twilio.AlertProvider)(nil)
-	_ AlertProvider = (*slack.AlertProvider)(nil)
+	_ AlertProvider = (*discord.AlertProvider)(nil)
+	_ AlertProvider = (*email.AlertProvider)(nil)
+	_ AlertProvider = (*googlechat.AlertProvider)(nil)
+	_ AlertProvider = (*matrix.AlertProvider)(nil)
 	_ AlertProvider = (*mattermost.AlertProvider)(nil)
 	_ AlertProvider = (*messagebird.AlertProvider)(nil)
+	_ AlertProvider = (*ntfy.AlertProvider)(nil)
+	_ AlertProvider = (*opsgenie.AlertProvider)(nil)
 	_ AlertProvider = (*pagerduty.AlertProvider)(nil)
+	_ AlertProvider = (*slack.AlertProvider)(nil)
+	_ AlertProvider = (*teams.AlertProvider)(nil)
+	_ AlertProvider = (*telegram.AlertProvider)(nil)
+	_ AlertProvider = (*twilio.AlertProvider)(nil)
 )

alerting/provider/provider_test.go

@@ -0,0 +1,153 @@
+package provider
+
+import (
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+)
+
+func TestParseWithDefaultAlert(t *testing.T) {
+	type Scenario struct {
+		Name                                             string
+		DefaultAlert, EndpointAlert, ExpectedOutputAlert *alert.Alert
+	}
+	enabled := true
+	disabled := false
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []Scenario{
+		{
+			Name: "endpoint-alert-type-only",
+			DefaultAlert: &alert.Alert{
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type: alert.TypeDiscord,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+		},
+		{
+			Name: "endpoint-alert-overwrites-default-alert",
+			DefaultAlert: &alert.Alert{
+				Enabled:          &disabled,
+				SendOnResolved:   &disabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type:             alert.TypeTelegram,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &secondDescription,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeTelegram,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &secondDescription,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+		},
+		{
+			Name: "endpoint-alert-partially-overwrites-default-alert",
+			DefaultAlert: &alert.Alert{
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          nil,
+				SendOnResolved:   nil,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 6,
+				SuccessThreshold: 11,
+			},
+		},
+		{
+			Name: "default-alert-type-should-be-ignored",
+			DefaultAlert: &alert.Alert{
+				Type:             alert.TypeTelegram,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+			EndpointAlert: &alert.Alert{
+				Type: alert.TypeDiscord,
+			},
+			ExpectedOutputAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          &enabled,
+				SendOnResolved:   &enabled,
+				Description:      &firstDescription,
+				FailureThreshold: 5,
+				SuccessThreshold: 10,
+			},
+		},
+		{
+			Name: "no-default-alert",
+			DefaultAlert: &alert.Alert{
+				Type:             alert.TypeDiscord,
+				Enabled:          nil,
+				SendOnResolved:   nil,
+				Description:      &firstDescription,
+				FailureThreshold: 2,
+				SuccessThreshold: 5,
+			},
+			EndpointAlert:       nil,
+			ExpectedOutputAlert: nil,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			ParseWithDefaultAlert(scenario.DefaultAlert, scenario.EndpointAlert)
+			if scenario.ExpectedOutputAlert == nil {
+				if scenario.EndpointAlert != nil {
+					t.Fail()
+				}
+				return
+			}
+			if scenario.EndpointAlert.IsEnabled() != scenario.ExpectedOutputAlert.IsEnabled() {
+				t.Errorf("expected EndpointAlert.IsEnabled() to be %v, got %v", scenario.ExpectedOutputAlert.IsEnabled(), scenario.EndpointAlert.IsEnabled())
+			}
+			if scenario.EndpointAlert.IsSendingOnResolved() != scenario.ExpectedOutputAlert.IsSendingOnResolved() {
+				t.Errorf("expected EndpointAlert.IsSendingOnResolved() to be %v, got %v", scenario.ExpectedOutputAlert.IsSendingOnResolved(), scenario.EndpointAlert.IsSendingOnResolved())
+			}
+			if scenario.EndpointAlert.GetDescription() != scenario.ExpectedOutputAlert.GetDescription() {
+				t.Errorf("expected EndpointAlert.GetDescription() to be %v, got %v", scenario.ExpectedOutputAlert.GetDescription(), scenario.EndpointAlert.GetDescription())
+			}
+			if scenario.EndpointAlert.FailureThreshold != scenario.ExpectedOutputAlert.FailureThreshold {
+				t.Errorf("expected EndpointAlert.FailureThreshold to be %v, got %v", scenario.ExpectedOutputAlert.FailureThreshold, scenario.EndpointAlert.FailureThreshold)
+			}
+			if scenario.EndpointAlert.SuccessThreshold != scenario.ExpectedOutputAlert.SuccessThreshold {
+				t.Errorf("expected EndpointAlert.SuccessThreshold to be %v, got %v", scenario.ExpectedOutputAlert.SuccessThreshold, scenario.EndpointAlert.SuccessThreshold)
+			}
+		})
+	}
+}

alerting/provider/slack/slack.go

@@ -1,63 +1,142 @@
 package slack
 
 import (
+	"bytes"
+	"encoding/json"
 	"fmt"
+	"io"
 	"net/http"
 
-	"github.com/TwinProduction/gatus/alerting/provider/custom"
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
 )
 
 // AlertProvider is the configuration necessary for sending an alert using Slack
 type AlertProvider struct {
+	WebhookURL string `yaml:"webhook-url"` // Slack webhook URL
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group      string `yaml:"group"`
 	WebhookURL string `yaml:"webhook-url"`
 }
 
 // IsValid returns whether the provider's configuration is valid
 func (provider *AlertProvider) IsValid() bool {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
 	return len(provider.WebhookURL) > 0
 }
 
-// ToCustomAlertProvider converts the provider into a custom.AlertProvider
-func (provider *AlertProvider) ToCustomAlertProvider(service *core.Service, alert *core.Alert, result *core.Result, resolved bool) *custom.AlertProvider {
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, provider.getWebhookURLForGroup(endpoint.Group), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Text        string       `json:"text"`
+	Attachments []Attachment `json:"attachments"`
+}
+
+type Attachment struct {
+	Title  string  `json:"title"`
+	Text   string  `json:"text"`
+	Short  bool    `json:"short"`
+	Color  string  `json:"color"`
+	Fields []Field `json:"fields"`
+}
+
+type Field struct {
+	Title string `json:"title"`
+	Value string `json:"value"`
+	Short bool   `json:"short"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
 	var message, color, results string
 	if resolved {
-		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", service.Name, alert.SuccessThreshold)
+		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
 		color = "#36A64F"
 	} else {
-		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", service.Name, alert.FailureThreshold)
+		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
 		color = "#DD0000"
 	}
 	for _, conditionResult := range result.ConditionResults {
 		var prefix string
 		if conditionResult.Success {
-			prefix = ":heavy_check_mark:"
+			prefix = ":white_check_mark:"
 		} else {
 			prefix = ":x:"
 		}
 		results += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
 	}
-	return &custom.AlertProvider{
-		URL:    provider.WebhookURL,
-		Method: http.MethodPost,
-		Body: fmt.Sprintf(`{
-  "text": "",
-  "attachments": [
-    {
-      "title": ":helmet_with_white_cross: Gatus",
-      "text": "%s:\n> %s",
-      "short": false,
-      "color": "%s",
-      "fields": [
-        {
-          "title": "Condition results",
-          "value": "%s",
-          "short": false
-        }
-      ]
-    }
-  ]
-}`, message, alert.Description, color, results),
-		Headers: map[string]string{"Content-Type": "application/json"},
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ":\n> " + alertDescription
 	}
+	body, _ := json.Marshal(Body{
+		Text: "",
+		Attachments: []Attachment{
+			{
+				Title: ":helmet_with_white_cross: Gatus",
+				Text:  message + description,
+				Short: false,
+				Color: color,
+				Fields: []Field{
+					{
+						Title: "Condition results",
+						Value: results,
+						Short: false,
+					},
+				},
+			},
+		},
+	})
+	return body
+}
+
+// getWebhookURLForGroup returns the appropriate Webhook URL integration to for a given group
+func (provider *AlertProvider) getWebhookURLForGroup(group string) string {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.WebhookURL
+			}
+		}
+	}
+	return provider.WebhookURL
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
 }

alerting/provider/slack/slack_test.go

@@ -1,41 +1,277 @@
 package slack
 
 import (
-	"strings"
+	"encoding/json"
+	"net/http"
 	"testing"
 
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
 )
 
-func TestAlertProvider_IsValid(t *testing.T) {
+func TestAlertDefaultProvider_IsValid(t *testing.T) {
 	invalidProvider := AlertProvider{WebhookURL: ""}
 	if invalidProvider.IsValid() {
 		t.Error("provider shouldn't have been valid")
 	}
-	validProvider := AlertProvider{WebhookURL: "http://example.com"}
+	validProvider := AlertProvider{WebhookURL: "https://example.com"}
 	if !validProvider.IsValid() {
 		t.Error("provider should've been valid")
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithResolvedAlert(t *testing.T) {
-	provider := AlertProvider{WebhookURL: "http://example.com"}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{ConditionResults: []*core.ConditionResult{{Condition: "SUCCESSFUL_CONDITION", Success: true}}}, true)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "",
+			},
+		},
 	}
-	if !strings.Contains(customAlertProvider.Body, "resolved") {
-		t.Error("customAlertProvider.Body should've contained the substring resolved")
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "",
+				Group:      "group",
+			},
+		},
+	}
+	if providerWithInvalidOverrideTo.IsValid() {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		WebhookURL: "http://example.com",
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "group",
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithTriggeredAlert(t *testing.T) {
-	provider := AlertProvider{WebhookURL: "http://example.com"}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{ConditionResults: []*core.ConditionResult{{Condition: "UNSUCCESSFUL_CONDITION", Success: false}}}, false)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
 	}
-	if !strings.Contains(customAlertProvider.Body, "triggered") {
-		t.Error("customAlertProvider.Body should've contained the substring triggered")
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Endpoint     core.Endpoint
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Endpoint:     core.Endpoint{Name: "name"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"short\":false,\"color\":\"#DD0000\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "triggered-with-group",
+			Provider:     AlertProvider{},
+			Endpoint:     core.Endpoint{Name: "name", Group: "group"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *group/name* has been triggered due to having failed 3 time(s) in a row:\\n\\u003e description-1\",\"short\":false,\"color\":\"#DD0000\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":x: - `[CONNECTED] == true`\\n:x: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Endpoint:     core.Endpoint{Name: "name"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *name* has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"short\":false,\"color\":\"#36A64F\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+		{
+			Name:         "resolved-with-group",
+			Provider:     AlertProvider{},
+			Endpoint:     core.Endpoint{Name: "name", Group: "group"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"text\":\"\",\"attachments\":[{\"title\":\":helmet_with_white_cross: Gatus\",\"text\":\"An alert for *group/name* has been resolved after passing successfully 5 time(s) in a row:\\n\\u003e description-2\",\"short\":false,\"color\":\"#36A64F\",\"fields\":[{\"title\":\"Condition results\",\"value\":\":white_check_mark: - `[CONNECTED] == true`\\n:white_check_mark: - `[STATUS] == 200`\\n\",\"short\":false}]}]}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&scenario.Endpoint,
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getWebhookURLForGroup(t *testing.T) {
+	tests := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput string
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example01.com",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			if got := tt.Provider.getWebhookURLForGroup(tt.InputGroup); got != tt.ExpectedOutput {
+				t.Errorf("AlertProvider.getWebhookURLForGroup() = %v, want %v", got, tt.ExpectedOutput)
+			}
+		})
 	}
 }

alerting/provider/teams/teams.go

@@ -0,0 +1,135 @@
+package teams
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+// AlertProvider is the configuration necessary for sending an alert using Teams
+type AlertProvider struct {
+	WebhookURL string `yaml:"webhook-url"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+
+	// Overrides is a list of Override that may be prioritized over the default configuration
+	Overrides []Override `yaml:"overrides,omitempty"`
+}
+
+// Override is a case under which the default integration is overridden
+type Override struct {
+	Group      string `yaml:"group"`
+	WebhookURL string `yaml:"webhook-url"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	registeredGroups := make(map[string]bool)
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if isAlreadyRegistered := registeredGroups[override.Group]; isAlreadyRegistered || override.Group == "" || len(override.WebhookURL) == 0 {
+				return false
+			}
+			registeredGroups[override.Group] = true
+		}
+	}
+	return len(provider.WebhookURL) > 0
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	request, err := http.NewRequest(http.MethodPost, provider.getWebhookURLForGroup(endpoint.Group), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	Type       string    `json:"@type"`
+	Context    string    `json:"@context"`
+	ThemeColor string    `json:"themeColor"`
+	Title      string    `json:"title"`
+	Text       string    `json:"text"`
+	Sections   []Section `json:"sections"`
+}
+
+type Section struct {
+	ActivityTitle string `json:"activityTitle"`
+	Text          string `json:"text"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	var message, color string
+	if resolved {
+		message = fmt.Sprintf("An alert for *%s* has been resolved after passing successfully %d time(s) in a row", endpoint.DisplayName(), alert.SuccessThreshold)
+		color = "#36A64F"
+	} else {
+		message = fmt.Sprintf("An alert for *%s* has been triggered due to having failed %d time(s) in a row", endpoint.DisplayName(), alert.FailureThreshold)
+		color = "#DD0000"
+	}
+	var results string
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		results += fmt.Sprintf("%s - `%s`<br/>", prefix, conditionResult.Condition)
+	}
+	var description string
+	if alertDescription := alert.GetDescription(); len(alertDescription) > 0 {
+		description = ": " + alertDescription
+	}
+	body, _ := json.Marshal(Body{
+		Type:       "MessageCard",
+		Context:    "http://schema.org/extensions",
+		ThemeColor: color,
+		Title:      "&#x1F6A8; Gatus",
+		Text:       message + description,
+		Sections: []Section{
+			{
+				ActivityTitle: "Condition results",
+				Text:          results,
+			},
+		},
+	})
+	return body
+}
+
+// getWebhookURLForGroup returns the appropriate Webhook URL integration to for a given group
+func (provider *AlertProvider) getWebhookURLForGroup(group string) string {
+	if provider.Overrides != nil {
+		for _, override := range provider.Overrides {
+			if group == override.Group {
+				return override.WebhookURL
+			}
+		}
+	}
+	return provider.WebhookURL
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/teams/teams_test.go

@@ -0,0 +1,258 @@
+package teams
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
+)
+
+func TestAlertDefaultProvider_IsValid(t *testing.T) {
+	invalidProvider := AlertProvider{WebhookURL: ""}
+	if invalidProvider.IsValid() {
+		t.Error("provider shouldn't have been valid")
+	}
+	validProvider := AlertProvider{WebhookURL: "http://example.com"}
+	if !validProvider.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_IsValidWithOverride(t *testing.T) {
+	providerWithInvalidOverrideGroup := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "",
+			},
+		},
+	}
+	if providerWithInvalidOverrideGroup.IsValid() {
+		t.Error("provider Group shouldn't have been valid")
+	}
+	providerWithInvalidOverrideTo := AlertProvider{
+		Overrides: []Override{
+			{
+				WebhookURL: "",
+				Group:      "group",
+			},
+		},
+	}
+	if providerWithInvalidOverrideTo.IsValid() {
+		t.Error("provider integration key shouldn't have been valid")
+	}
+	providerWithValidOverride := AlertProvider{
+		WebhookURL: "http://example.com",
+		Overrides: []Override{
+			{
+				WebhookURL: "http://example.com",
+				Group:      "group",
+			},
+		},
+	}
+	if !providerWithValidOverride.IsValid() {
+		t.Error("provider should've been valid")
+	}
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"@type\":\"MessageCard\",\"@context\":\"http://schema.org/extensions\",\"themeColor\":\"#DD0000\",\"title\":\"\\u0026#x1F6A8; Gatus\",\"text\":\"An alert for *endpoint-name* has been triggered due to having failed 3 time(s) in a row: description-1\",\"sections\":[{\"activityTitle\":\"Condition results\",\"text\":\"\\u0026#x274C; - `[CONNECTED] == true`\\u003cbr/\\u003e\\u0026#x274C; - `[STATUS] == 200`\\u003cbr/\\u003e\"}]}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"@type\":\"MessageCard\",\"@context\":\"http://schema.org/extensions\",\"themeColor\":\"#36A64F\",\"title\":\"\\u0026#x1F6A8; Gatus\",\"text\":\"An alert for *endpoint-name* has been resolved after passing successfully 5 time(s) in a row: description-2\",\"sections\":[{\"activityTitle\":\"Condition results\",\"text\":\"\\u0026#x2705; - `[CONNECTED] == true`\\u003cbr/\\u003e\\u0026#x2705; - `[STATUS] == 200`\\u003cbr/\\u003e\"}]}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}
+
+func TestAlertProvider_getWebhookURLForGroup(t *testing.T) {
+	tests := []struct {
+		Name           string
+		Provider       AlertProvider
+		InputGroup     string
+		ExpectedOutput string
+	}{
+		{
+			Name: "provider-no-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-no-override-specify-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides:  nil,
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-no-group-should-default",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "",
+			ExpectedOutput: "http://example.com",
+		},
+		{
+			Name: "provider-with-override-specify-group-should-override",
+			Provider: AlertProvider{
+				WebhookURL: "http://example.com",
+				Overrides: []Override{
+					{
+						Group:      "group",
+						WebhookURL: "http://example01.com",
+					},
+				},
+			},
+			InputGroup:     "group",
+			ExpectedOutput: "http://example01.com",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			if got := tt.Provider.getWebhookURLForGroup(tt.InputGroup); got != tt.ExpectedOutput {
+				t.Errorf("AlertProvider.getToForGroup() = %v, want %v", got, tt.ExpectedOutput)
+			}
+		})
+	}
+}

alerting/provider/telegram/telegram.go

@@ -0,0 +1,102 @@
+package telegram
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+)
+
+const defaultAPIURL = "https://api.telegram.org"
+
+// AlertProvider is the configuration necessary for sending an alert using Telegram
+type AlertProvider struct {
+	Token  string `yaml:"token"`
+	ID     string `yaml:"id"`
+	APIURL string `yaml:"api-url"`
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
+}
+
+// IsValid returns whether the provider's configuration is valid
+func (provider *AlertProvider) IsValid() bool {
+	if provider.ClientConfig == nil {
+		provider.ClientConfig = client.GetDefaultConfig()
+	}
+	return len(provider.Token) > 0 && len(provider.ID) > 0
+}
+
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer(provider.buildRequestBody(endpoint, alert, result, resolved))
+	apiURL := provider.APIURL
+	if apiURL == "" {
+		apiURL = defaultAPIURL
+	}
+	request, err := http.NewRequest(http.MethodPost, fmt.Sprintf("%s/bot%s/sendMessage", apiURL, provider.Token), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/json")
+	response, err := client.GetHTTPClient(provider.ClientConfig).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+type Body struct {
+	ChatID    string `json:"chat_id"`
+	Text      string `json:"text"`
+	ParseMode string `json:"parse_mode"`
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) []byte {
+	var message, results string
+	if resolved {
+		message = fmt.Sprintf("An alert for *%s* has been resolved:\n—\n    _healthcheck passing successfully %d time(s) in a row_\n—  ", endpoint.DisplayName(), alert.FailureThreshold)
+	} else {
+		message = fmt.Sprintf("An alert for *%s* has been triggered:\n—\n    _healthcheck failed %d time(s) in a row_\n—  ", endpoint.DisplayName(), alert.FailureThreshold)
+	}
+	for _, conditionResult := range result.ConditionResults {
+		var prefix string
+		if conditionResult.Success {
+			prefix = "✅"
+		} else {
+			prefix = "❌"
+		}
+		results += fmt.Sprintf("%s - `%s`\n", prefix, conditionResult.Condition)
+	}
+	var text string
+	if len(alert.GetDescription()) > 0 {
+		text = fmt.Sprintf("⛑ *Gatus* \n%s \n*Description* \n_%s_  \n\n*Condition results*\n%s", message, alert.GetDescription(), results)
+	} else {
+		text = fmt.Sprintf("⛑ *Gatus* \n%s \n*Condition results*\n%s", message, results)
+	}
+	body, _ := json.Marshal(Body{
+		ChatID:    provider.ID,
+		Text:      text,
+		ParseMode: "MARKDOWN",
+	})
+	return body
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
+}

alerting/provider/telegram/telegram_test.go

@@ -0,0 +1,168 @@
+package telegram
+
+import (
+	"encoding/json"
+	"net/http"
+	"testing"
+
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/test"
+)
+
+func TestAlertProvider_IsValid(t *testing.T) {
+	t.Run("invalid-provider", func(t *testing.T) {
+		invalidProvider := AlertProvider{Token: "", ID: ""}
+		if invalidProvider.IsValid() {
+			t.Error("provider shouldn't have been valid")
+		}
+	})
+	t.Run("valid-provider", func(t *testing.T) {
+		validProvider := AlertProvider{Token: "123456:ABC-DEF1234ghIkl-zyx57W2v1u123ew11", ID: "12345678"}
+		if validProvider.ClientConfig != nil {
+			t.Error("provider client config should have been nil prior to IsValid() being executed")
+		}
+		if !validProvider.IsValid() {
+			t.Error("provider should've been valid")
+		}
+		if validProvider.ClientConfig == nil {
+			t.Error("provider client config should have been set after IsValid() was executed")
+		}
+	})
+}
+
+func TestAlertProvider_Send(t *testing.T) {
+	defer client.InjectHTTPClient(nil)
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name             string
+		Provider         AlertProvider
+		Alert            alert.Alert
+		Resolved         bool
+		MockRoundTripper test.MockRoundTripper
+		ExpectedError    bool
+	}{
+		{
+			Name:     "triggered",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "triggered-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: false,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+		{
+			Name:     "resolved",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusOK, Body: http.NoBody}
+			}),
+			ExpectedError: false,
+		},
+		{
+			Name:     "resolved-error",
+			Provider: AlertProvider{},
+			Alert:    alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved: true,
+			MockRoundTripper: test.MockRoundTripper(func(r *http.Request) *http.Response {
+				return &http.Response{StatusCode: http.StatusInternalServerError, Body: http.NoBody}
+			}),
+			ExpectedError: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			client.InjectHTTPClient(&http.Client{Transport: scenario.MockRoundTripper})
+			err := scenario.Provider.Send(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if scenario.ExpectedError && err == nil {
+				t.Error("expected error, got none")
+			}
+			if !scenario.ExpectedError && err != nil {
+				t.Error("expected no error, got", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{ID: "123"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "{\"chat_id\":\"123\",\"text\":\"⛑ *Gatus* \\nAn alert for *endpoint-name* has been triggered:\\n—\\n    _healthcheck failed 3 time(s) in a row_\\n—   \\n*Description* \\n_description-1_  \\n\\n*Condition results*\\n❌ - `[CONNECTED] == true`\\n❌ - `[STATUS] == 200`\\n\",\"parse_mode\":\"MARKDOWN\"}",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{ID: "123"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "{\"chat_id\":\"123\",\"text\":\"⛑ *Gatus* \\nAn alert for *endpoint-name* has been resolved:\\n—\\n    _healthcheck passing successfully 3 time(s) in a row_\\n—   \\n*Description* \\n_description-2_  \\n\\n*Condition results*\\n✅ - `[CONNECTED] == true`\\n✅ - `[STATUS] == 200`\\n\",\"parse_mode\":\"MARKDOWN\"}",
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if string(body) != scenario.ExpectedBody {
+				t.Errorf("expected:\n%s\ngot:\n%s", scenario.ExpectedBody, body)
+			}
+			out := make(map[string]interface{})
+			if err := json.Unmarshal(body, &out); err != nil {
+				t.Error("expected body to be valid JSON, got error:", err.Error())
+			}
+		})
+	}
+}
+
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
+	}
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
+	}
+}

alerting/provider/twilio/twilio.go

@@ -1,13 +1,16 @@
 package twilio
 
 import (
+	"bytes"
 	"encoding/base64"
 	"fmt"
+	"io"
 	"net/http"
 	"net/url"
 
-	"github.com/TwinProduction/gatus/alerting/provider/custom"
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/client"
+	"github.com/TwiN/gatus/v4/core"
 )
 
 // AlertProvider is the configuration necessary for sending an alert using Twilio
@@ -16,6 +19,9 @@ type AlertProvider struct {
 	Token string `yaml:"token"`
 	From  string `yaml:"from"`
 	To    string `yaml:"to"`
+
+	// DefaultAlert is the default alert configuration to use for endpoints with an alert of the appropriate type
+	DefaultAlert *alert.Alert `yaml:"default-alert,omitempty"`
 }
 
 // IsValid returns whether the provider's configuration is valid
@@ -23,25 +29,43 @@ func (provider *AlertProvider) IsValid() bool {
 	return len(provider.Token) > 0 && len(provider.SID) > 0 && len(provider.From) > 0 && len(provider.To) > 0
 }
 
-// ToCustomAlertProvider converts the provider into a custom.AlertProvider
-func (provider *AlertProvider) ToCustomAlertProvider(service *core.Service, alert *core.Alert, _ *core.Result, resolved bool) *custom.AlertProvider {
+// Send an alert using the provider
+func (provider *AlertProvider) Send(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) error {
+	buffer := bytes.NewBuffer([]byte(provider.buildRequestBody(endpoint, alert, result, resolved)))
+	request, err := http.NewRequest(http.MethodPost, fmt.Sprintf("https://api.twilio.com/2010-04-01/Accounts/%s/Messages.json", provider.SID), buffer)
+	if err != nil {
+		return err
+	}
+	request.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	request.Header.Set("Authorization", fmt.Sprintf("Basic %s", base64.StdEncoding.EncodeToString([]byte(provider.SID+":"+provider.Token))))
+	response, err := client.GetHTTPClient(nil).Do(request)
+	if err != nil {
+		return err
+	}
+	defer response.Body.Close()
+	if response.StatusCode > 399 {
+		body, _ := io.ReadAll(response.Body)
+		return fmt.Errorf("call to provider alert returned status code %d: %s", response.StatusCode, string(body))
+	}
+	return err
+}
+
+// buildRequestBody builds the request body for the provider
+func (provider *AlertProvider) buildRequestBody(endpoint *core.Endpoint, alert *alert.Alert, result *core.Result, resolved bool) string {
 	var message string
 	if resolved {
-		message = fmt.Sprintf("RESOLVED: %s - %s", service.Name, alert.Description)
+		message = fmt.Sprintf("RESOLVED: %s - %s", endpoint.DisplayName(), alert.GetDescription())
 	} else {
-		message = fmt.Sprintf("TRIGGERED: %s - %s", service.Name, alert.Description)
-	}
-	return &custom.AlertProvider{
-		URL:    fmt.Sprintf("https://api.twilio.com/2010-04-01/Accounts/%s/Messages.json", provider.SID),
-		Method: http.MethodPost,
-		Body: url.Values{
-			"To":   {provider.To},
-			"From": {provider.From},
-			"Body": {message},
-		}.Encode(),
-		Headers: map[string]string{
-			"Content-Type":  "application/x-www-form-urlencoded",
-			"Authorization": fmt.Sprintf("Basic %s", base64.StdEncoding.EncodeToString([]byte(fmt.Sprintf("%s:%s", provider.SID, provider.Token)))),
-		},
+		message = fmt.Sprintf("TRIGGERED: %s - %s", endpoint.DisplayName(), alert.GetDescription())
 	}
+	return url.Values{
+		"To":   {provider.To},
+		"From": {provider.From},
+		"Body": {message},
+	}.Encode()
+}
+
+// GetDefaultAlert returns the provider's default alert configuration
+func (provider AlertProvider) GetDefaultAlert() *alert.Alert {
+	return provider.DefaultAlert
 }

alerting/provider/twilio/twilio_test.go

@@ -1,10 +1,10 @@
 package twilio
 
 import (
-	"strings"
 	"testing"
 
-	"github.com/TwinProduction/gatus/core"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/core"
 )
 
 func TestTwilioAlertProvider_IsValid(t *testing.T) {
@@ -23,34 +23,56 @@ func TestTwilioAlertProvider_IsValid(t *testing.T) {
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithResolvedAlert(t *testing.T) {
-	provider := AlertProvider{
-		SID:   "1",
-		Token: "1",
-		From:  "1",
-		To:    "1",
+func TestAlertProvider_buildRequestBody(t *testing.T) {
+	firstDescription := "description-1"
+	secondDescription := "description-2"
+	scenarios := []struct {
+		Name         string
+		Provider     AlertProvider
+		Alert        alert.Alert
+		Resolved     bool
+		ExpectedBody string
+	}{
+		{
+			Name:         "triggered",
+			Provider:     AlertProvider{SID: "1", Token: "2", From: "3", To: "4"},
+			Alert:        alert.Alert{Description: &firstDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     false,
+			ExpectedBody: "Body=TRIGGERED%3A+endpoint-name+-+description-1&From=3&To=4",
+		},
+		{
+			Name:         "resolved",
+			Provider:     AlertProvider{SID: "1", Token: "2", From: "3", To: "4"},
+			Alert:        alert.Alert{Description: &secondDescription, SuccessThreshold: 5, FailureThreshold: 3},
+			Resolved:     true,
+			ExpectedBody: "Body=RESOLVED%3A+endpoint-name+-+description-2&From=3&To=4",
+		},
 	}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, true)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
-	}
-	if !strings.Contains(customAlertProvider.Body, "RESOLVED") {
-		t.Error("customAlertProvider.Body should've contained the substring RESOLVED")
+	for _, scenario := range scenarios {
+		t.Run(scenario.Name, func(t *testing.T) {
+			body := scenario.Provider.buildRequestBody(
+				&core.Endpoint{Name: "endpoint-name"},
+				&scenario.Alert,
+				&core.Result{
+					ConditionResults: []*core.ConditionResult{
+						{Condition: "[CONNECTED] == true", Success: scenario.Resolved},
+						{Condition: "[STATUS] == 200", Success: scenario.Resolved},
+					},
+				},
+				scenario.Resolved,
+			)
+			if body != scenario.ExpectedBody {
+				t.Errorf("expected %s, got %s", scenario.ExpectedBody, body)
+			}
+		})
 	}
 }
 
-func TestAlertProvider_ToCustomAlertProviderWithTriggeredAlert(t *testing.T) {
-	provider := AlertProvider{
-		SID:   "1",
-		Token: "1",
-		From:  "1",
-		To:    "1",
+func TestAlertProvider_GetDefaultAlert(t *testing.T) {
+	if (AlertProvider{DefaultAlert: &alert.Alert{}}).GetDefaultAlert() == nil {
+		t.Error("expected default alert to be not nil")
 	}
-	customAlertProvider := provider.ToCustomAlertProvider(&core.Service{}, &core.Alert{}, &core.Result{}, false)
-	if customAlertProvider == nil {
-		t.Error("customAlertProvider shouldn't have been nil")
-	}
-	if !strings.Contains(customAlertProvider.Body, "TRIGGERED") {
-		t.Error("customAlertProvider.Body should've contained the substring TRIGGERED")
+	if (AlertProvider{DefaultAlert: nil}).GetDefaultAlert() != nil {
+		t.Error("expected default alert to be nil")
 	}
 }

client/client.go

@@ -2,50 +2,73 @@ package client
 
 import (
 	"crypto/tls"
+	"crypto/x509"
+	"errors"
+	"fmt"
 	"net"
 	"net/http"
+	"net/smtp"
+	"runtime"
+	"strings"
 	"time"
 
+	"github.com/TwiN/gocache/v2"
+	"github.com/TwiN/whois"
 	"github.com/go-ping/ping"
+	"github.com/ishidawataru/sctp"
 )
 
 var (
-	secureHTTPClient   *http.Client
-	insecureHTTPClient *http.Client
+	// injectedHTTPClient is used for testing purposes
+	injectedHTTPClient *http.Client
+
+	whoisClient              = whois.NewClient().WithReferralCache(true)
+	whoisExpirationDateCache = gocache.NewCache().WithMaxSize(10000).WithDefaultTTL(24 * time.Hour)
 )
 
-// GetHTTPClient returns the shared HTTP client
-func GetHTTPClient(insecure bool) *http.Client {
-	if insecure {
-		if insecureHTTPClient == nil {
-			insecureHTTPClient = &http.Client{
-				Timeout: 10 * time.Second,
-				Transport: &http.Transport{
-					MaxIdleConns:        100,
-					MaxIdleConnsPerHost: 20,
-					TLSClientConfig: &tls.Config{
-						InsecureSkipVerify: true,
-					},
-				},
-			}
-		}
-		return insecureHTTPClient
+// GetHTTPClient returns the shared HTTP client, or the client from the configuration passed
+func GetHTTPClient(config *Config) *http.Client {
+	if injectedHTTPClient != nil {
+		return injectedHTTPClient
 	}
-	if secureHTTPClient == nil {
-		secureHTTPClient = &http.Client{
-			Timeout: 10 * time.Second,
-			Transport: &http.Transport{
-				MaxIdleConns:        100,
-				MaxIdleConnsPerHost: 20,
-			},
-		}
+	if config == nil {
+		return defaultConfig.getHTTPClient()
 	}
-	return secureHTTPClient
+	return config.getHTTPClient()
 }
 
-// CanCreateTCPConnection checks whether a connection can be established with a TCP service
-func CanCreateTCPConnection(address string) bool {
-	conn, err := net.DialTimeout("tcp", address, 5*time.Second)
+// GetDomainExpiration retrieves the duration until the domain provided expires
+func GetDomainExpiration(hostname string) (domainExpiration time.Duration, err error) {
+	var retrievedCachedValue bool
+	if v, exists := whoisExpirationDateCache.Get(hostname); exists {
+		domainExpiration = time.Until(v.(time.Time))
+		retrievedCachedValue = true
+		// If the domain OR the TTL is not going to expire in less than 24 hours
+		// we don't have to refresh the cache. Otherwise, we'll refresh it.
+		cacheEntryTTL, _ := whoisExpirationDateCache.TTL(hostname)
+		if cacheEntryTTL > 24*time.Hour && domainExpiration > 24*time.Hour {
+			// No need to refresh, so we'll just return the cached values
+			return domainExpiration, nil
+		}
+	}
+	if whoisResponse, err := whoisClient.QueryAndParse(hostname); err != nil {
+		if !retrievedCachedValue { // Add an error unless we already retrieved a cached value
+			return 0, fmt.Errorf("error querying and parsing hostname using whois client: %w", err)
+		}
+	} else {
+		domainExpiration = time.Until(whoisResponse.ExpirationDate)
+		if domainExpiration > 720*time.Hour {
+			whoisExpirationDateCache.SetWithTTL(hostname, whoisResponse.ExpirationDate, 240*time.Hour)
+		} else {
+			whoisExpirationDateCache.SetWithTTL(hostname, whoisResponse.ExpirationDate, 72*time.Hour)
+		}
+	}
+	return domainExpiration, nil
+}
+
+// CanCreateTCPConnection checks whether a connection can be established with a TCP endpoint
+func CanCreateTCPConnection(address string, config *Config) bool {
+	conn, err := net.DialTimeout("tcp", address, config.Timeout)
 	if err != nil {
 		return false
 	}
@@ -53,24 +76,115 @@ func CanCreateTCPConnection(address string) bool {
 	return true
 }
 
+// CanCreateUDPConnection checks whether a connection can be established with a UDP endpoint
+func CanCreateUDPConnection(address string, config *Config) bool {
+	conn, err := net.DialTimeout("udp", address, config.Timeout)
+	if err != nil {
+		return false
+	}
+	_ = conn.Close()
+	return true
+}
+
+// CanCreateSCTPConnection checks whether a connection can be established with a SCTP endpoint
+func CanCreateSCTPConnection(address string, config *Config) bool {
+	ch := make(chan bool)
+	go (func(res chan bool) {
+		addr, err := sctp.ResolveSCTPAddr("sctp", address)
+		if err != nil {
+			res <- false
+		}
+
+		conn, err := sctp.DialSCTP("sctp", nil, addr)
+		if err != nil {
+			res <- false
+		}
+		_ = conn.Close()
+		res <- true
+	})(ch)
+
+	select {
+	case result := <-ch:
+		return result
+	case <-time.After(config.Timeout):
+		return false
+	}
+}
+
+// CanPerformStartTLS checks whether a connection can be established to an address using the STARTTLS protocol
+func CanPerformStartTLS(address string, config *Config) (connected bool, certificate *x509.Certificate, err error) {
+	hostAndPort := strings.Split(address, ":")
+	if len(hostAndPort) != 2 {
+		return false, nil, errors.New("invalid address for starttls, format must be host:port")
+	}
+	connection, err := net.DialTimeout("tcp", address, config.Timeout)
+	if err != nil {
+		return
+	}
+	smtpClient, err := smtp.NewClient(connection, hostAndPort[0])
+	if err != nil {
+		return
+	}
+	err = smtpClient.StartTLS(&tls.Config{
+		InsecureSkipVerify: config.Insecure,
+		ServerName:         hostAndPort[0],
+	})
+	if err != nil {
+		return
+	}
+	if state, ok := smtpClient.TLSConnectionState(); ok {
+		certificate = state.PeerCertificates[0]
+	} else {
+		return false, nil, errors.New("could not get TLS connection state")
+	}
+	return true, certificate, nil
+}
+
+// CanPerformTLS checks whether a connection can be established to an address using the TLS protocol
+func CanPerformTLS(address string, config *Config) (connected bool, certificate *x509.Certificate, err error) {
+	connection, err := tls.DialWithDialer(&net.Dialer{Timeout: config.Timeout}, "tcp", address, nil)
+	if err != nil {
+		return
+	}
+	defer connection.Close()
+	verifiedChains := connection.ConnectionState().VerifiedChains
+	if len(verifiedChains) == 0 || len(verifiedChains[0]) == 0 {
+		return
+	}
+	return true, verifiedChains[0][0], nil
+}
+
 // Ping checks if an address can be pinged and returns the round-trip time if the address can be pinged
 //
 // Note that this function takes at least 100ms, even if the address is 127.0.0.1
-func Ping(address string) (bool, time.Duration) {
+func Ping(address string, config *Config) (bool, time.Duration) {
 	pinger, err := ping.NewPinger(address)
 	if err != nil {
 		return false, 0
 	}
 	pinger.Count = 1
-	pinger.Timeout = 5 * time.Second
-	pinger.SetNetwork("ip4")
-	pinger.SetPrivileged(true)
+	pinger.Timeout = config.Timeout
+	// Set the pinger's privileged mode to true for every GOOS except darwin
+	// See https://github.com/TwiN/gatus/issues/132
+	//
+	// Note that for this to work on Linux, Gatus must run with sudo privileges.
+	// See https://github.com/go-ping/ping#linux
+	pinger.SetPrivileged(runtime.GOOS != "darwin")
 	err = pinger.Run()
 	if err != nil {
 		return false, 0
 	}
 	if pinger.Statistics() != nil {
+		// If the packet loss is 100, it means that the packet didn't reach the host
+		if pinger.Statistics().PacketLoss == 100 {
+			return false, pinger.Timeout
+		}
 		return true, pinger.Statistics().MaxRtt
 	}
 	return true, 0
 }
+
+// InjectHTTPClient is used to inject a custom HTTP client for testing purposes
+func InjectHTTPClient(httpClient *http.Client) {
+	injectedHTTPClient = httpClient
+}

client/client_test.go

@@ -1,43 +1,248 @@
 package client
 
 import (
+	"bytes"
+	"io"
+	"net/http"
 	"testing"
+	"time"
+
+	"github.com/TwiN/gatus/v4/test"
 )
 
 func TestGetHTTPClient(t *testing.T) {
-	if secureHTTPClient != nil {
-		t.Error("secureHTTPClient should've been nil since it hasn't been called a single time yet")
+	cfg := &Config{
+		Insecure:       false,
+		IgnoreRedirect: false,
+		Timeout:        0,
+		DNSResolver:    "tcp://1.1.1.1:53",
+		OAuth2Config: &OAuth2Config{
+			ClientID:     "00000000-0000-0000-0000-000000000000",
+			ClientSecret: "secretsauce",
+			TokenURL:     "https://token-server.local/token",
+			Scopes:       []string{"https://application.local/.default"},
+		},
 	}
-	if insecureHTTPClient != nil {
-		t.Error("insecureHTTPClient should've been nil since it hasn't been called a single time yet")
+	err := cfg.ValidateAndSetDefaults()
+	if err != nil {
+		t.Errorf("expected error to be nil, but got: `%s`", err)
 	}
-	_ = GetHTTPClient(false)
-	if secureHTTPClient == nil {
-		t.Error("secureHTTPClient shouldn't have been nil, since it has been called once")
+	if GetHTTPClient(cfg) == nil {
+		t.Error("expected client to not be nil")
 	}
-	if insecureHTTPClient != nil {
-		t.Error("insecureHTTPClient should've been nil since it hasn't been called a single time yet")
+	if GetHTTPClient(nil) == nil {
+		t.Error("expected client to not be nil")
 	}
-	_ = GetHTTPClient(true)
-	if secureHTTPClient == nil {
-		t.Error("secureHTTPClient shouldn't have been nil, since it has been called once")
+}
+
+func TestGetDomainExpiration(t *testing.T) {
+	if domainExpiration, err := GetDomainExpiration("example.com"); err != nil {
+		t.Fatalf("expected error to be nil, but got: `%s`", err)
+	} else if domainExpiration <= 0 {
+		t.Error("expected domain expiration to be higher than 0")
 	}
-	if insecureHTTPClient == nil {
-		t.Error("insecureHTTPClient shouldn't have been nil, since it has been called once")
+	if domainExpiration, err := GetDomainExpiration("example.com"); err != nil {
+		t.Errorf("expected error to be nil, but got: `%s`", err)
+	} else if domainExpiration <= 0 {
+		t.Error("expected domain expiration to be higher than 0")
+	}
+	// Hack to pretend like the domain is expiring in 1 hour, which should trigger a refresh
+	whoisExpirationDateCache.SetWithTTL("example.com", time.Now().Add(time.Hour), 25*time.Hour)
+	if domainExpiration, err := GetDomainExpiration("example.com"); err != nil {
+		t.Errorf("expected error to be nil, but got: `%s`", err)
+	} else if domainExpiration <= 0 {
+		t.Error("expected domain expiration to be higher than 0")
+	}
+	// Make sure the refresh works when the ttl is <24 hours
+	whoisExpirationDateCache.SetWithTTL("example.com", time.Now().Add(35*time.Hour), 23*time.Hour)
+	if domainExpiration, err := GetDomainExpiration("example.com"); err != nil {
+		t.Errorf("expected error to be nil, but got: `%s`", err)
+	} else if domainExpiration <= 0 {
+		t.Error("expected domain expiration to be higher than 0")
 	}
 }
 
 func TestPing(t *testing.T) {
-	if success, rtt := Ping("127.0.0.1"); !success {
+	if success, rtt := Ping("127.0.0.1", &Config{Timeout: 500 * time.Millisecond}); !success {
 		t.Error("expected true")
 		if rtt == 0 {
 			t.Error("Round-trip time returned on success should've higher than 0")
 		}
 	}
-	if success, rtt := Ping("256.256.256.256"); success {
-		t.Error("expected false")
+	if success, rtt := Ping("256.256.256.256", &Config{Timeout: 500 * time.Millisecond}); success {
+		t.Error("expected false, because the IP is invalid")
+		if rtt != 0 {
+			t.Error("Round-trip time returned on failure should've been 0")
+		}
+	}
+	if success, rtt := Ping("192.168.152.153", &Config{Timeout: 500 * time.Millisecond}); success {
+		t.Error("expected false, because the IP is valid but the host should be unreachable")
 		if rtt != 0 {
 			t.Error("Round-trip time returned on failure should've been 0")
 		}
 	}
 }
+
+func TestCanPerformStartTLS(t *testing.T) {
+	type args struct {
+		address  string
+		insecure bool
+	}
+	tests := []struct {
+		name          string
+		args          args
+		wantConnected bool
+		wantErr       bool
+	}{
+		{
+			name: "invalid address",
+			args: args{
+				address: "test",
+			},
+			wantConnected: false,
+			wantErr:       true,
+		},
+		{
+			name: "error dial",
+			args: args{
+				address: "test:1234",
+			},
+			wantConnected: false,
+			wantErr:       true,
+		},
+		{
+			name: "valid starttls",
+			args: args{
+				address: "smtp.gmail.com:587",
+			},
+			wantConnected: true,
+			wantErr:       false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			connected, _, err := CanPerformStartTLS(tt.args.address, &Config{Insecure: tt.args.insecure, Timeout: 5 * time.Second})
+			if (err != nil) != tt.wantErr {
+				t.Errorf("CanPerformStartTLS() err=%v, wantErr=%v", err, tt.wantErr)
+				return
+			}
+			if connected != tt.wantConnected {
+				t.Errorf("CanPerformStartTLS() connected=%v, wantConnected=%v", connected, tt.wantConnected)
+			}
+		})
+	}
+}
+
+func TestCanPerformTLS(t *testing.T) {
+	type args struct {
+		address  string
+		insecure bool
+	}
+	tests := []struct {
+		name          string
+		args          args
+		wantConnected bool
+		wantErr       bool
+	}{
+		{
+			name: "invalid address",
+			args: args{
+				address: "test",
+			},
+			wantConnected: false,
+			wantErr:       true,
+		},
+		{
+			name: "error dial",
+			args: args{
+				address: "test:1234",
+			},
+			wantConnected: false,
+			wantErr:       true,
+		},
+		{
+			name: "valid tls",
+			args: args{
+				address: "smtp.gmail.com:465",
+			},
+			wantConnected: true,
+			wantErr:       false,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			connected, _, err := CanPerformTLS(tt.args.address, &Config{Insecure: tt.args.insecure, Timeout: 5 * time.Second})
+			if (err != nil) != tt.wantErr {
+				t.Errorf("CanPerformTLS() err=%v, wantErr=%v", err, tt.wantErr)
+				return
+			}
+			if connected != tt.wantConnected {
+				t.Errorf("CanPerformTLS() connected=%v, wantConnected=%v", connected, tt.wantConnected)
+			}
+		})
+	}
+}
+
+func TestCanCreateTCPConnection(t *testing.T) {
+	if CanCreateTCPConnection("127.0.0.1", &Config{Timeout: 5 * time.Second}) {
+		t.Error("should've failed, because there's no port in the address")
+	}
+}
+
+// This test checks if a HTTP client configured with `configureOAuth2()` automatically
+// performs a Client Credentials OAuth2 flow and adds the obtained token as a `Authorization`
+// header to all outgoing HTTP calls.
+func TestHttpClientProvidesOAuth2BearerToken(t *testing.T) {
+	defer InjectHTTPClient(nil)
+	oAuth2Config := &OAuth2Config{
+		ClientID:     "00000000-0000-0000-0000-000000000000",
+		ClientSecret: "secretsauce",
+		TokenURL:     "https://token-server.local/token",
+		Scopes:       []string{"https://application.local/.default"},
+	}
+	mockHttpClient := &http.Client{
+		Transport: test.MockRoundTripper(func(r *http.Request) *http.Response {
+			// if the mock HTTP client tries to get a token from the `token-server`
+			// we provide the expected token response
+			if r.Host == "token-server.local" {
+				return &http.Response{
+					StatusCode: http.StatusOK,
+					Body: io.NopCloser(bytes.NewReader(
+						[]byte(
+							`{"token_type":"Bearer","expires_in":3599,"ext_expires_in":3599,"access_token":"secret-token"}`,
+						),
+					)),
+				}
+			}
+			// to verify the headers were sent as expected, we echo them back in the
+			// `X-Org-Authorization` header and check if the token value matches our
+			// mocked `token-server` response
+			return &http.Response{
+				StatusCode: http.StatusOK,
+				Header: map[string][]string{
+					"X-Org-Authorization": {r.Header.Get("Authorization")},
+				},
+				Body: http.NoBody,
+			}
+		}),
+	}
+	mockHttpClientWithOAuth := configureOAuth2(mockHttpClient, *oAuth2Config)
+	InjectHTTPClient(mockHttpClientWithOAuth)
+	request, err := http.NewRequest(http.MethodPost, "http://127.0.0.1:8282", http.NoBody)
+	if err != nil {
+		t.Error("expected no error, got", err.Error())
+	}
+	response, err := mockHttpClientWithOAuth.Do(request)
+	if err != nil {
+		t.Error("expected no error, got", err.Error())
+	}
+	if response.Header == nil {
+		t.Error("expected response headers, but got nil")
+	}
+	// the mock response echos the Authorization header used in the request back
+	// to us as `X-Org-Authorization` header, we check here if the value matches
+	// our expected token `secret-token`
+	if response.Header.Get("X-Org-Authorization") != "Bearer secret-token" {
+		t.Error("exptected `secret-token` as Bearer token in the mocked response header `X-Org-Authorization`, but got", response.Header.Get("X-Org-Authorization"))
+	}
+}

client/config.go

@@ -0,0 +1,199 @@
+package client
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"log"
+	"net"
+	"net/http"
+	"regexp"
+	"strconv"
+	"time"
+
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/clientcredentials"
+)
+
+const (
+	defaultHTTPTimeout = 10 * time.Second
+)
+
+var (
+	ErrInvalidDNSResolver        = errors.New("invalid DNS resolver specified. Required format is {proto}://{ip}:{port}")
+	ErrInvalidDNSResolverPort    = errors.New("invalid DNS resolver port")
+	ErrInvalidClientOAuth2Config = errors.New("invalid OAuth2 configuration, all fields are required")
+
+	defaultConfig = Config{
+		Insecure:       false,
+		IgnoreRedirect: false,
+		Timeout:        defaultHTTPTimeout,
+	}
+)
+
+// GetDefaultConfig returns a copy of the default configuration
+func GetDefaultConfig() *Config {
+	cfg := defaultConfig
+	return &cfg
+}
+
+// Config is the configuration for clients
+type Config struct {
+	// Insecure determines whether to skip verifying the server's certificate chain and host name
+	Insecure bool `yaml:"insecure,omitempty"`
+
+	// IgnoreRedirect determines whether to ignore redirects (true) or follow them (false, default)
+	IgnoreRedirect bool `yaml:"ignore-redirect,omitempty"`
+
+	// Timeout for the client
+	Timeout time.Duration `yaml:"timeout"`
+
+	// DNSResolver override for the HTTP client
+	// Expected format is {protocol}://{host}:{port}, e.g. tcp://8.8.8.8:53
+	DNSResolver string `yaml:"dns-resolver,omitempty"`
+
+	// OAuth2Config is the OAuth2 configuration used for the client.
+	//
+	// If non-nil, the http.Client returned by getHTTPClient will automatically retrieve a token if necessary.
+	// See configureOAuth2 for more details.
+	OAuth2Config *OAuth2Config `yaml:"oauth2,omitempty"`
+
+	httpClient *http.Client
+}
+
+// DNSResolverConfig is the parsed configuration from the DNSResolver config string.
+type DNSResolverConfig struct {
+	Protocol string
+	Host     string
+	Port     string
+}
+
+// OAuth2Config is the configuration for the OAuth2 client credentials flow
+type OAuth2Config struct {
+	TokenURL     string   `yaml:"token-url"` // e.g. https://dev-12345678.okta.com/token
+	ClientID     string   `yaml:"client-id"`
+	ClientSecret string   `yaml:"client-secret"`
+	Scopes       []string `yaml:"scopes"` // e.g. ["openid"]
+}
+
+// ValidateAndSetDefaults validates the client configuration and sets the default values if necessary
+func (c *Config) ValidateAndSetDefaults() error {
+	if c.Timeout < time.Millisecond {
+		c.Timeout = 10 * time.Second
+	}
+	if c.HasCustomDNSResolver() {
+		// Validate the DNS resolver now to make sure it will not return an error later.
+		if _, err := c.parseDNSResolver(); err != nil {
+			return err
+		}
+	}
+	if c.HasOAuth2Config() && !c.OAuth2Config.isValid() {
+		return ErrInvalidClientOAuth2Config
+	}
+	return nil
+}
+
+// HasCustomDNSResolver returns whether a custom DNSResolver is configured
+func (c *Config) HasCustomDNSResolver() bool {
+	return len(c.DNSResolver) > 0
+}
+
+// parseDNSResolver parses the DNS resolver into the DNSResolverConfig struct
+func (c *Config) parseDNSResolver() (*DNSResolverConfig, error) {
+	re := regexp.MustCompile(`^(?P<proto>(.*))://(?P<host>[A-Za-z0-9\-\.]+):(?P<port>[0-9]+)?(.*)$`)
+	matches := re.FindStringSubmatch(c.DNSResolver)
+	if len(matches) == 0 {
+		return nil, ErrInvalidDNSResolver
+	}
+	r := make(map[string]string)
+	for i, k := range re.SubexpNames() {
+		if i != 0 && k != "" {
+			r[k] = matches[i]
+		}
+	}
+	port, err := strconv.Atoi(r["port"])
+	if err != nil {
+		return nil, err
+	}
+	if port < 1 || port > 65535 {
+		return nil, ErrInvalidDNSResolverPort
+	}
+	return &DNSResolverConfig{
+		Protocol: r["proto"],
+		Host:     r["host"],
+		Port:     r["port"],
+	}, nil
+}
+
+// HasOAuth2Config returns true if the client has OAuth2 configuration parameters
+func (c *Config) HasOAuth2Config() bool {
+	return c.OAuth2Config != nil
+}
+
+// isValid() returns true if the OAuth2 configuration is valid
+func (c *OAuth2Config) isValid() bool {
+	return len(c.TokenURL) > 0 && len(c.ClientID) > 0 && len(c.ClientSecret) > 0 && len(c.Scopes) > 0
+}
+
+// GetHTTPClient return an HTTP client matching the Config's parameters.
+func (c *Config) getHTTPClient() *http.Client {
+	if c.httpClient == nil {
+		c.httpClient = &http.Client{
+			Timeout: c.Timeout,
+			Transport: &http.Transport{
+				MaxIdleConns:        100,
+				MaxIdleConnsPerHost: 20,
+				Proxy:               http.ProxyFromEnvironment,
+				TLSClientConfig: &tls.Config{
+					InsecureSkipVerify: c.Insecure,
+				},
+			},
+			CheckRedirect: func(req *http.Request, via []*http.Request) error {
+				if c.IgnoreRedirect {
+					// Don't follow redirects
+					return http.ErrUseLastResponse
+				}
+				// Follow redirects
+				return nil
+			},
+		}
+		if c.HasCustomDNSResolver() {
+			dnsResolver, err := c.parseDNSResolver()
+			if err != nil {
+				// We're ignoring the error, because it should have been validated on startup ValidateAndSetDefaults.
+				// It shouldn't happen, but if it does, we'll log it... Better safe than sorry ;)
+				log.Println("[client][getHTTPClient] THIS SHOULD NOT HAPPEN. Silently ignoring invalid DNS resolver due to error:", err.Error())
+			} else {
+				dialer := &net.Dialer{
+					Resolver: &net.Resolver{
+						PreferGo: true,
+						Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
+							d := net.Dialer{}
+							return d.DialContext(ctx, dnsResolver.Protocol, dnsResolver.Host+":"+dnsResolver.Port)
+						},
+					},
+				}
+				c.httpClient.Transport.(*http.Transport).DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
+					return dialer.DialContext(ctx, network, addr)
+				}
+			}
+		}
+		if c.HasOAuth2Config() {
+			c.httpClient = configureOAuth2(c.httpClient, *c.OAuth2Config)
+		}
+	}
+	return c.httpClient
+}
+
+// configureOAuth2 returns an HTTP client that will obtain and refresh tokens as necessary.
+// The returned Client and its Transport should not be modified.
+func configureOAuth2(httpClient *http.Client, c OAuth2Config) *http.Client {
+	oauth2cfg := clientcredentials.Config{
+		ClientID:     c.ClientID,
+		ClientSecret: c.ClientSecret,
+		Scopes:       c.Scopes,
+		TokenURL:     c.TokenURL,
+	}
+	ctx := context.WithValue(context.Background(), oauth2.HTTPClient, httpClient)
+	return oauth2cfg.Client(ctx)
+}

client/config_test.go

@@ -0,0 +1,81 @@
+package client
+
+import (
+	"net/http"
+	"testing"
+	"time"
+)
+
+func TestConfig_getHTTPClient(t *testing.T) {
+	insecureConfig := &Config{Insecure: true}
+	insecureConfig.ValidateAndSetDefaults()
+	insecureClient := insecureConfig.getHTTPClient()
+	if !(insecureClient.Transport).(*http.Transport).TLSClientConfig.InsecureSkipVerify {
+		t.Error("expected Config.Insecure set to true to cause the HTTP client to skip certificate verification")
+	}
+	if insecureClient.Timeout != defaultHTTPTimeout {
+		t.Error("expected Config.Timeout to default the HTTP client to a timeout of 10s")
+	}
+	request, _ := http.NewRequest("GET", "", nil)
+	if err := insecureClient.CheckRedirect(request, nil); err != nil {
+		t.Error("expected Config.IgnoreRedirect set to false to cause the HTTP client's CheckRedirect to return nil")
+	}
+
+	secureConfig := &Config{IgnoreRedirect: true, Timeout: 5 * time.Second}
+	secureConfig.ValidateAndSetDefaults()
+	secureClient := secureConfig.getHTTPClient()
+	if (secureClient.Transport).(*http.Transport).TLSClientConfig.InsecureSkipVerify {
+		t.Error("expected Config.Insecure set to false to cause the HTTP client to not skip certificate verification")
+	}
+	if secureClient.Timeout != 5*time.Second {
+		t.Error("expected Config.Timeout to cause the HTTP client to have a timeout of 5s")
+	}
+	request, _ = http.NewRequest("GET", "", nil)
+	if err := secureClient.CheckRedirect(request, nil); err != http.ErrUseLastResponse {
+		t.Error("expected Config.IgnoreRedirect set to true to cause the HTTP client's CheckRedirect to return http.ErrUseLastResponse")
+	}
+}
+
+func TestConfig_ValidateAndSetDefaults_withCustomDNSResolver(t *testing.T) {
+	type args struct {
+		dnsResolver string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantErr bool
+	}{
+		{
+			name: "with-valid-resolver",
+			args: args{
+				dnsResolver: "tcp://1.1.1.1:53",
+			},
+			wantErr: false,
+		},
+		{
+			name: "with-invalid-resolver-port",
+			args: args{
+				dnsResolver: "tcp://127.0.0.1:99999",
+			},
+			wantErr: true,
+		},
+		{
+			name: "with-invalid-resolver-format",
+			args: args{
+				dnsResolver: "foobar",
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cfg := &Config{
+				DNSResolver: tt.args.dnsResolver,
+			}
+			err := cfg.ValidateAndSetDefaults()
+			if (err != nil) != tt.wantErr {
+				t.Errorf("ValidateAndSetDefaults() error=%v, wantErr=%v", err, tt.wantErr)
+			}
+		})
+	}
+}

config.yaml

@@ -1,23 +1,24 @@
-services:
-  - name: frontend
+endpoints:
+  - name: front-end
     group: core
-    url: "https://twinnation.org/health"
-    interval: 1m
-    conditions:
-      - "[STATUS] == 200"
-      - "[BODY].status == UP"
-      - "[RESPONSE_TIME] < 70"
-
-  - name: backend
-    group: core
-    url: "http://example.org/"
+    url: "https://twin.sh/health"
     interval: 5m
     conditions:
       - "[STATUS] == 200"
+      - "[BODY].status == UP"
+      - "[RESPONSE_TIME] < 150"
+
+  - name: back-end
+    group: core
+    url: "https://example.org/"
+    interval: 5m
+    conditions:
+      - "[STATUS] == 200"
+      - "[CERTIFICATE_EXPIRATION] > 48h"
 
   - name: monitoring
     group: internal
-    url: "http://example.com/"
+    url: "https://example.org/"
     interval: 5m
     conditions:
       - "[STATUS] == 200"
@@ -29,10 +30,24 @@ services:
     conditions:
       - "[STATUS] == 200"
 
-  - name: cat-fact
-    url: "https://cat-fact.herokuapp.com/facts/random"
+  - name: example-dns-query
+    url: "8.8.8.8" # Address of the DNS server to use
     interval: 5m
+    dns:
+      query-name: "example.com"
+      query-type: "A"
     conditions:
-      - "[STATUS] == 200"
-      - "[BODY].deleted == false"
-      - "len([BODY].text) > 0"
+      - "[BODY] == 93.184.216.34"
+      - "[DNS_RCODE] == NOERROR"
+
+  - name: icmp-ping
+    url: "icmp://example.org"
+    interval: 1m
+    conditions:
+      - "[CONNECTED] == true"
+
+  - name: check-domain-expiration
+    url: "https://example.org/"
+    interval: 1h
+    conditions:
+      - "[DOMAIN_EXPIRATION] > 720h"

config/config.go

@@ -2,15 +2,22 @@ package config
 
 import (
 	"errors"
-	"io/ioutil"
+	"fmt"
 	"log"
 	"os"
+	"time"
 
-	"github.com/TwinProduction/gatus/alerting"
-	"github.com/TwinProduction/gatus/alerting/provider"
-	"github.com/TwinProduction/gatus/core"
-	"github.com/TwinProduction/gatus/k8s"
-	"github.com/TwinProduction/gatus/security"
+	"github.com/TwiN/gatus/v4/alerting"
+	"github.com/TwiN/gatus/v4/alerting/alert"
+	"github.com/TwiN/gatus/v4/alerting/provider"
+	"github.com/TwiN/gatus/v4/config/maintenance"
+	"github.com/TwiN/gatus/v4/config/remote"
+	"github.com/TwiN/gatus/v4/config/ui"
+	"github.com/TwiN/gatus/v4/config/web"
+	"github.com/TwiN/gatus/v4/core"
+	"github.com/TwiN/gatus/v4/security"
+	"github.com/TwiN/gatus/v4/storage"
+	"github.com/TwiN/gatus/v4/util"
 	"gopkg.in/yaml.v2"
 )
 
@@ -22,165 +29,253 @@ const (
 	// DefaultFallbackConfigurationFilePath is the default fallback path that will be used to search for the
 	// configuration file if DefaultConfigurationFilePath didn't work
 	DefaultFallbackConfigurationFilePath = "config/config.yml"
-
-	// DefaultAddress is the default address the service will bind to
-	DefaultAddress = "0.0.0.0"
-
-	// DefaultPort is the default port the service will listen on
-	DefaultPort = 8080
-
-	// DefaultContextRoot is the default context root of the web application
-	DefaultContextRoot = "/"
 )
 
 var (
-	// ErrNoServiceInConfig is an error returned when a configuration file has no services configured
-	ErrNoServiceInConfig = errors.New("configuration file should contain at least 1 service")
+	// ErrNoEndpointInConfig is an error returned when a configuration file has no endpoints configured
+	ErrNoEndpointInConfig = errors.New("configuration file should contain at least 1 endpoint")
 
 	// ErrConfigFileNotFound is an error returned when the configuration file could not be found
 	ErrConfigFileNotFound = errors.New("configuration file not found")
 
-	// ErrConfigNotLoaded is an error returned when an attempt to Get() the configuration before loading it is made
-	ErrConfigNotLoaded = errors.New("configuration is nil")
-
 	// ErrInvalidSecurityConfig is an error returned when the security configuration is invalid
 	ErrInvalidSecurityConfig = errors.New("invalid security configuration")
-
-	config *Config
 )
 
 // Config is the main configuration structure
 type Config struct {
 	// Debug Whether to enable debug logs
-	Debug bool `yaml:"debug"`
+	Debug bool `yaml:"debug,omitempty"`
 
 	// Metrics Whether to expose metrics at /metrics
-	Metrics bool `yaml:"metrics"`
+	Metrics bool `yaml:"metrics,omitempty"`
+
+	// SkipInvalidConfigUpdate Whether to make the application ignore invalid configuration
+	// if the configuration file is updated while the application is running
+	SkipInvalidConfigUpdate bool `yaml:"skip-invalid-config-update,omitempty"`
 
 	// DisableMonitoringLock Whether to disable the monitoring lock
-	// The monitoring lock is what prevents multiple services from being processed at the same time.
+	// The monitoring lock is what prevents multiple endpoints from being processed at the same time.
 	// Disabling this may lead to inaccurate response times
-	DisableMonitoringLock bool `yaml:"disable-monitoring-lock"`
+	DisableMonitoringLock bool `yaml:"disable-monitoring-lock,omitempty"`
 
 	// Security Configuration for securing access to Gatus
-	Security *security.Config `yaml:"security"`
+	Security *security.Config `yaml:"security,omitempty"`
 
 	// Alerting Configuration for alerting
-	Alerting *alerting.Config `yaml:"alerting"`
+	Alerting *alerting.Config `yaml:"alerting,omitempty"`
 
-	// Services List of services to monitor
-	Services []*core.Service `yaml:"services"`
+	// Endpoints List of endpoints to monitor
+	Endpoints []*core.Endpoint `yaml:"endpoints,omitempty"`
 
-	// Kubernetes is the Kubernetes configuration
-	Kubernetes *k8s.Config `yaml:"kubernetes"`
+	// Services List of endpoints to monitor
+	//
+	// XXX: Remove this in v5.0.0
+	// XXX: This is not a typo -- not v4.0.0, but v5.0.0 -- I want to give enough time for people to migrate
+	//
+	// Deprecated in favor of Endpoints
+	Services []*core.Endpoint `yaml:"services,omitempty"`
 
-	// Web is the configuration for the web listener
-	Web *webConfig `yaml:"web"`
+	// Storage is the configuration for how the data is stored
+	Storage *storage.Config `yaml:"storage,omitempty"`
+
+	// Web is the web configuration for the application
+	Web *web.Config `yaml:"web,omitempty"`
+
+	// UI is the configuration for the UI
+	UI *ui.Config `yaml:"ui,omitempty"`
+
+	// Maintenance is the configuration for creating a maintenance window in which no alerts are sent
+	Maintenance *maintenance.Config `yaml:"maintenance,omitempty"`
+
+	// Remote is the configuration for remote Gatus instances
+	// WARNING: This is in ALPHA and may change or be completely removed in the future
+	Remote *remote.Config `yaml:"remote,omitempty"`
+
+	filePath        string    // path to the file from which config was loaded from
+	lastFileModTime time.Time // last modification time
 }
 
-// Get returns the configuration, or panics if the configuration hasn't loaded yet
-func Get() *Config {
-	if config == nil {
-		panic(ErrConfigNotLoaded)
+func (config *Config) GetEndpointByKey(key string) *core.Endpoint {
+	for i := 0; i < len(config.Endpoints); i++ {
+		ep := config.Endpoints[i]
+		if util.ConvertGroupAndEndpointNameToKey(ep.Group, ep.Name) == key {
+			return ep
+		}
+	}
+	return nil
+}
+
+// HasLoadedConfigurationFileBeenModified returns whether the file that the
+// configuration has been loaded from has been modified since it was last read
+func (config Config) HasLoadedConfigurationFileBeenModified() bool {
+	if fileInfo, err := os.Stat(config.filePath); err == nil {
+		if !fileInfo.ModTime().IsZero() {
+			return config.lastFileModTime.Unix() != fileInfo.ModTime().Unix()
+		}
+	}
+	return false
+}
+
+// UpdateLastFileModTime refreshes Config.lastFileModTime
+func (config *Config) UpdateLastFileModTime() {
+	if fileInfo, err := os.Stat(config.filePath); err == nil {
+		if !fileInfo.ModTime().IsZero() {
+			config.lastFileModTime = fileInfo.ModTime()
+		}
+	} else {
+		log.Println("[config][UpdateLastFileModTime] Ran into error updating lastFileModTime:", err.Error())
 	}
-	return config
 }
 
 // Load loads a custom configuration file
 // Note that the misconfiguration of some fields may lead to panics. This is on purpose.
-func Load(configFile string) error {
+func Load(configFile string) (*Config, error) {
 	log.Printf("[config][Load] Reading configuration from configFile=%s", configFile)
 	cfg, err := readConfigurationFile(configFile)
 	if err != nil {
 		if os.IsNotExist(err) {
-			return ErrConfigFileNotFound
+			return nil, ErrConfigFileNotFound
 		}
-		return err
+		return nil, err
 	}
-	config = cfg
-	return nil
+	cfg.filePath = configFile
+	cfg.UpdateLastFileModTime()
+	return cfg, nil
 }
 
 // LoadDefaultConfiguration loads the default configuration file
-func LoadDefaultConfiguration() error {
-	err := Load(DefaultConfigurationFilePath)
+func LoadDefaultConfiguration() (*Config, error) {
+	cfg, err := Load(DefaultConfigurationFilePath)
 	if err != nil {
 		if err == ErrConfigFileNotFound {
 			return Load(DefaultFallbackConfigurationFilePath)
 		}
-		return err
+		return nil, err
 	}
-	return nil
+	return cfg, nil
 }
 
 func readConfigurationFile(fileName string) (config *Config, err error) {
 	var bytes []byte
-	if bytes, err = ioutil.ReadFile(fileName); err == nil {
+	if bytes, err = os.ReadFile(fileName); err == nil {
 		// file exists, so we'll parse it and return it
 		return parseAndValidateConfigBytes(bytes)
 	}
 	return
 }
 
+// parseAndValidateConfigBytes parses a Gatus configuration file into a Config struct and validates its parameters
 func parseAndValidateConfigBytes(yamlBytes []byte) (config *Config, err error) {
 	// Expand environment variables
 	yamlBytes = []byte(os.ExpandEnv(string(yamlBytes)))
 	// Parse configuration file
-	err = yaml.Unmarshal(yamlBytes, &config)
-	if err != nil {
+	if err = yaml.Unmarshal(yamlBytes, &config); err != nil {
 		return
 	}
-	// Check if the configuration file at least has services configured or Kubernetes auto discovery enabled
-	if config == nil || ((config.Services == nil || len(config.Services) == 0) && (config.Kubernetes == nil || !config.Kubernetes.AutoDiscover)) {
-		err = ErrNoServiceInConfig
+	if config != nil && len(config.Services) > 0 { // XXX: Remove this in v5.0.0
+		log.Println("WARNING: Your configuration is using 'services:', which is deprecated in favor of 'endpoints:'.")
+		log.Println("WARNING: See https://github.com/TwiN/gatus/issues/191 for more information")
+		config.Endpoints = append(config.Endpoints, config.Services...)
+		config.Services = nil
+	}
+	// Check if the configuration file at least has endpoints configured
+	if config == nil || config.Endpoints == nil || len(config.Endpoints) == 0 {
+		err = ErrNoEndpointInConfig
 	} else {
-		// Note that the functions below may panic, and this is on purpose to prevent Gatus from starting with
-		// invalid configurations
-		validateAlertingConfig(config)
-		validateSecurityConfig(config)
-		validateServicesConfig(config)
-		validateKubernetesConfig(config)
-		validateWebConfig(config)
+		validateAlertingConfig(config.Alerting, config.Endpoints, config.Debug)
+		if err := validateSecurityConfig(config); err != nil {
+			return nil, err
+		}
+		if err := validateEndpointsConfig(config); err != nil {
+			return nil, err
+		}
+		if err := validateWebConfig(config); err != nil {
+			return nil, err
+		}
+		if err := validateUIConfig(config); err != nil {
+			return nil, err
+		}
+		if err := validateMaintenanceConfig(config); err != nil {
+			return nil, err
+		}
+		if err := validateStorageConfig(config); err != nil {
+			return nil, err
+		}
+		if err := validateRemoteConfig(config); err != nil {
+			return nil, err
+		}
 	}
 	return
 }
 
-func validateWebConfig(config *Config) {
-	if config.Web == nil {
-		config.Web = &webConfig{Address: DefaultAddress, Port: DefaultPort, ContextRoot: DefaultContextRoot}
+func validateRemoteConfig(config *Config) error {
+	if config.Remote != nil {
+		if err := config.Remote.ValidateAndSetDefaults(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func validateStorageConfig(config *Config) error {
+	if config.Storage == nil {
+		config.Storage = &storage.Config{
+			Type: storage.TypeMemory,
+		}
 	} else {
-		config.Web.validateAndSetDefaults()
+		if err := config.Storage.ValidateAndSetDefaults(); err != nil {
+			return err
+		}
 	}
+	return nil
 }
 
-func validateKubernetesConfig(config *Config) {
-	if config.Kubernetes != nil && config.Kubernetes.AutoDiscover {
-		if config.Kubernetes.ServiceTemplate == nil {
-			panic("kubernetes.service-template cannot be nil")
+func validateMaintenanceConfig(config *Config) error {
+	if config.Maintenance == nil {
+		config.Maintenance = maintenance.GetDefaultConfig()
+	} else {
+		if err := config.Maintenance.ValidateAndSetDefaults(); err != nil {
+			return err
 		}
+	}
+	return nil
+}
+
+func validateUIConfig(config *Config) error {
+	if config.UI == nil {
+		config.UI = ui.GetDefaultConfig()
+	} else {
+		if err := config.UI.ValidateAndSetDefaults(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func validateWebConfig(config *Config) error {
+	if config.Web == nil {
+		config.Web = web.GetDefaultConfig()
+	} else {
+		return config.Web.ValidateAndSetDefaults()
+	}
+	return nil
+}
+
+func validateEndpointsConfig(config *Config) error {
+	for _, endpoint := range config.Endpoints {
 		if config.Debug {
-			log.Println("[config][validateKubernetesConfig] Automatically discovering Kubernetes services...")
+			log.Printf("[config][validateEndpointsConfig] Validating endpoint '%s'", endpoint.Name)
 		}
-		discoveredServices, err := k8s.DiscoverServices(config.Kubernetes)
-		if err != nil {
-			panic(err)
+		if err := endpoint.ValidateAndSetDefaults(); err != nil {
+			return fmt.Errorf("invalid endpoint %s: %w", endpoint.DisplayName(), err)
 		}
-		config.Services = append(config.Services, discoveredServices...)
-		log.Printf("[config][validateKubernetesConfig] Discovered %d Kubernetes services", len(discoveredServices))
 	}
+	log.Printf("[config][validateEndpointsConfig] Validated %d endpoints", len(config.Endpoints))
+	return nil
 }
 
-func validateServicesConfig(config *Config) {
-	for _, service := range config.Services {
-		if config.Debug {
-			log.Printf("[config][validateServicesConfig] Validating service '%s'", service.Name)
-		}
-		service.ValidateAndSetDefaults()
-	}
-	log.Printf("[config][validateServicesConfig] Validated %d services", len(config.Services))
-}
-
-func validateSecurityConfig(config *Config) {
+func validateSecurityConfig(config *Config) error {
 	if config.Security != nil {
 		if config.Security.IsValid() {
 			if config.Debug {
@@ -189,29 +284,55 @@ func validateSecurityConfig(config *Config) {
 		} else {
 			// If there was an attempt to configure security, then it must mean that some confidential or private
 			// data are exposed. As a result, we'll force a panic because it's better to be safe than sorry.
-			panic(ErrInvalidSecurityConfig)
+			return ErrInvalidSecurityConfig
 		}
 	}
+	return nil
 }
 
-func validateAlertingConfig(config *Config) {
-	if config.Alerting == nil {
+// validateAlertingConfig validates the alerting configuration
+// Note that the alerting configuration has to be validated before the endpoint configuration, because the default alert
+// returned by provider.AlertProvider.GetDefaultAlert() must be parsed before core.Endpoint.ValidateAndSetDefaults()
+// sets the default alert values when none are set.
+func validateAlertingConfig(alertingConfig *alerting.Config, endpoints []*core.Endpoint, debug bool) {
+	if alertingConfig == nil {
 		log.Printf("[config][validateAlertingConfig] Alerting is not configured")
 		return
 	}
-	alertTypes := []core.AlertType{
-		core.SlackAlert,
-		core.MattermostAlert,
-		core.MessagebirdAlert,
-		core.TwilioAlert,
-		core.PagerDutyAlert,
-		core.CustomAlert,
+	alertTypes := []alert.Type{
+		alert.TypeCustom,
+		alert.TypeDiscord,
+		alert.TypeGoogleChat,
+		alert.TypeEmail,
+		alert.TypeMatrix,
+		alert.TypeMattermost,
+		alert.TypeMessagebird,
+		alert.TypeNtfy,
+		alert.TypeOpsgenie,
+		alert.TypePagerDuty,
+		alert.TypeSlack,
+		alert.TypeTeams,
+		alert.TypeTelegram,
+		alert.TypeTwilio,
 	}
-	var validProviders, invalidProviders []core.AlertType
+	var validProviders, invalidProviders []alert.Type
 	for _, alertType := range alertTypes {
-		alertProvider := GetAlertingProviderByAlertType(config, alertType)
+		alertProvider := alertingConfig.GetAlertingProviderByAlertType(alertType)
 		if alertProvider != nil {
 			if alertProvider.IsValid() {
+				// Parse alerts with the provider's default alert
+				if alertProvider.GetDefaultAlert() != nil {
+					for _, endpoint := range endpoints {
+						for alertIndex, endpointAlert := range endpoint.Alerts {
+							if alertType == endpointAlert.Type {
+								if debug {
+									log.Printf("[config][validateAlertingConfig] Parsing alert %d with provider's default alert for provider=%s in endpoint=%s", alertIndex, alertType, endpoint.Name)
+								}
+								provider.ParseWithDefaultAlert(alertProvider.GetDefaultAlert(), endpointAlert)
+							}
+						}
+					}
+				}
 				validProviders = append(validProviders, alertType)
 			} else {
 				log.Printf("[config][validateAlertingConfig] Ignoring provider=%s because configuration is invalid", alertType)
@@ -223,46 +344,3 @@ func validateAlertingConfig(config *Config) {
 	}
 	log.Printf("[config][validateAlertingConfig] configuredProviders=%s; ignoredProviders=%s", validProviders, invalidProviders)
 }
-
-// GetAlertingProviderByAlertType returns an provider.AlertProvider by its corresponding core.AlertType
-func GetAlertingProviderByAlertType(config *Config, alertType core.AlertType) provider.AlertProvider {
-	switch alertType {
-	case core.SlackAlert:
-		if config.Alerting.Slack == nil {
-			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
-			return nil
-		}
-		return config.Alerting.Slack
-	case core.MattermostAlert:
-		if config.Alerting.Mattermost == nil {
-			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
-			return nil
-		}
-		return config.Alerting.Mattermost
-	case core.MessagebirdAlert:
-		if config.Alerting.Messagebird == nil {
-			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
-			return nil
-		}
-		return config.Alerting.Messagebird
-	case core.TwilioAlert:
-		if config.Alerting.Twilio == nil {
-			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
-			return nil
-		}
-		return config.Alerting.Twilio
-	case core.PagerDutyAlert:
-		if config.Alerting.PagerDuty == nil {
-			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
-			return nil
-		}
-		return config.Alerting.PagerDuty
-	case core.CustomAlert:
-		if config.Alerting.Custom == nil {
-			// Since we're returning an interface, we need to explicitly return nil, even if the provider itself is nil
-			return nil
-		}
-		return config.Alerting.Custom
-	}
-	return nil
-}

config/maintenance/maintenance.go

@@ -0,0 +1,145 @@
+package maintenance
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"strings"
+	"time"
+)
+
+var (
+	errInvalidMaintenanceStartFormat = errors.New("invalid maintenance start format: must be hh:mm, between 00:00 and 23:59 inclusively (e.g. 23:00)")
+	errInvalidMaintenanceDuration    = errors.New("invalid maintenance duration: must be bigger than 0 (e.g. 30m)")
+	errInvalidDayName                = fmt.Errorf("invalid value specified for 'on'. supported values are %s", longDayNames)
+
+	longDayNames = []string{
+		"Sunday",
+		"Monday",
+		"Tuesday",
+		"Wednesday",
+		"Thursday",
+		"Friday",
+		"Saturday",
+	}
+)
+
+// Config allows for the configuration of a maintenance period.
+// During this maintenance period, no alerts will be sent.
+//
+// Uses UTC.
+type Config struct {
+	Enabled  *bool         `yaml:"enabled"`  // Whether the maintenance period is enabled. Enabled by default if nil.
+	Start    string        `yaml:"start"`    // Time at which the maintenance period starts (e.g. 23:00)
+	Duration time.Duration `yaml:"duration"` // Duration of the maintenance period (e.g. 4h)
+
+	// Every is a list of days of the week during which maintenance period applies.
+	// See longDayNames for list of valid values.
+	// Every day if empty.
+	Every []string `yaml:"every"`
+
+	durationToStartFromMidnight time.Duration
+}
+
+func GetDefaultConfig() *Config {
+	defaultValue := false
+	return &Config{
+		Enabled: &defaultValue,
+	}
+}
+
+// IsEnabled returns whether maintenance is enabled or not
+func (c Config) IsEnabled() bool {
+	if c.Enabled == nil {
+		return true
+	}
+	return *c.Enabled
+}
+
+// ValidateAndSetDefaults validates the maintenance configuration and sets the default values if necessary.
+//
+// Must be called once in the application's lifecycle before IsUnderMaintenance is called, since it
+// also sets durationToStartFromMidnight.
+func (c *Config) ValidateAndSetDefaults() error {
+	if c == nil || !c.IsEnabled() {
+		// Don't waste time validating if maintenance is not enabled.
+		return nil
+	}
+	for _, day := range c.Every {
+		isDayValid := false
+		for _, longDayName := range longDayNames {
+			if day == longDayName {
+				isDayValid = true
+				break
+			}
+		}
+		if !isDayValid {
+			return errInvalidDayName
+		}
+	}
+	var err error
+	c.durationToStartFromMidnight, err = hhmmToDuration(c.Start)
+	if err != nil {
+		return err
+	}
+	if c.Duration <= 0 || c.Duration >= 24*time.Hour {
+		return errInvalidMaintenanceDuration
+	}
+	return nil
+}
+
+// IsUnderMaintenance checks whether the endpoints that Gatus monitors are within the configured maintenance window
+func (c Config) IsUnderMaintenance() bool {
+	if !c.IsEnabled() {
+		return false
+	}
+	now := time.Now().UTC()
+	var dayWhereMaintenancePeriodWouldStart time.Time
+	if now.Hour() >= int(c.durationToStartFromMidnight.Hours()) {
+		dayWhereMaintenancePeriodWouldStart = now.Truncate(24 * time.Hour)
+	} else {
+		dayWhereMaintenancePeriodWouldStart = now.Add(-c.Duration).Truncate(24 * time.Hour)
+	}
+	hasMaintenanceEveryDay := len(c.Every) == 0
+	hasMaintenancePeriodScheduledToStartOnThatWeekday := c.hasDay(dayWhereMaintenancePeriodWouldStart.Weekday().String())
+	if !hasMaintenanceEveryDay && !hasMaintenancePeriodScheduledToStartOnThatWeekday {
+		// The day when the maintenance period would start is not scheduled
+		// to have any maintenance, so we can just return false.
+		return false
+	}
+	startOfMaintenancePeriod := dayWhereMaintenancePeriodWouldStart.Add(c.durationToStartFromMidnight)
+	endOfMaintenancePeriod := startOfMaintenancePeriod.Add(c.Duration)
+	return now.After(startOfMaintenancePeriod) && now.Before(endOfMaintenancePeriod)
+}
+
+func (c Config) hasDay(day string) bool {
+	for _, d := range c.Every {
+		if d == day {
+			return true
+		}
+	}
+	return false
+}
+
+func hhmmToDuration(s string) (time.Duration, error) {
+	if len(s) != 5 {
+		return 0, errInvalidMaintenanceStartFormat
+	}
+	var hours, minutes int
+	var err error
+	if hours, err = extractNumericalValueFromPotentiallyZeroPaddedString(s[:2]); err != nil {
+		return 0, err
+	}
+	if minutes, err = extractNumericalValueFromPotentiallyZeroPaddedString(s[3:5]); err != nil {
+		return 0, err
+	}
+	duration := (time.Duration(hours) * time.Hour) + (time.Duration(minutes) * time.Minute)
+	if hours < 0 || hours > 23 || minutes < 0 || minutes > 59 || duration < 0 || duration >= 24*time.Hour {
+		return 0, errInvalidMaintenanceStartFormat
+	}
+	return duration, nil
+}
+
+func extractNumericalValueFromPotentiallyZeroPaddedString(s string) (int, error) {
+	return strconv.Atoi(strings.TrimPrefix(s, "0"))
+}

config/maintenance/maintenance_test.go

@@ -0,0 +1,261 @@
+package maintenance
+
+import (
+	"errors"
+	"fmt"
+	"strconv"
+	"testing"
+	"time"
+)
+
+func TestGetDefaultConfig(t *testing.T) {
+	if *GetDefaultConfig().Enabled {
+		t.Fatal("expected default config to be disabled by default")
+	}
+}
+
+func TestConfig_ValidateAndSetDefaults(t *testing.T) {
+	yes, no := true, false
+	scenarios := []struct {
+		name          string
+		cfg           *Config
+		expectedError error
+	}{
+		{
+			name:          "nil",
+			cfg:           nil,
+			expectedError: nil,
+		},
+		{
+			name: "disabled",
+			cfg: &Config{
+				Enabled: &no,
+			},
+			expectedError: nil,
+		},
+		{
+			name: "invalid-day",
+			cfg: &Config{
+				Every: []string{"invalid-day"},
+			},
+			expectedError: errInvalidDayName,
+		},
+		{
+			name: "invalid-day",
+			cfg: &Config{
+				Every: []string{"invalid-day"},
+			},
+			expectedError: errInvalidDayName,
+		},
+		{
+			name: "invalid-start-format",
+			cfg: &Config{
+				Start: "0000",
+			},
+			expectedError: errInvalidMaintenanceStartFormat,
+		},
+		{
+			name: "invalid-start-hours",
+			cfg: &Config{
+				Start: "25:00",
+			},
+			expectedError: errInvalidMaintenanceStartFormat,
+		},
+		{
+			name: "invalid-start-minutes",
+			cfg: &Config{
+				Start: "0:61",
+			},
+			expectedError: errInvalidMaintenanceStartFormat,
+		},
+		{
+			name: "invalid-start-minutes-non-numerical",
+			cfg: &Config{
+				Start: "00:zz",
+			},
+			expectedError: strconv.ErrSyntax,
+		},
+		{
+			name: "invalid-start-hours-non-numerical",
+			cfg: &Config{
+				Start: "zz:00",
+			},
+			expectedError: strconv.ErrSyntax,
+		},
+		{
+			name: "invalid-duration",
+			cfg: &Config{
+				Start:    "23:00",
+				Duration: 0,
+			},
+			expectedError: errInvalidMaintenanceDuration,
+		},
+		{
+			name: "every-day-at-2300",
+			cfg: &Config{
+				Start:    "23:00",
+				Duration: time.Hour,
+			},
+			expectedError: nil,
+		},
+		{
+			name: "every-day-explicitly-at-2300",
+			cfg: &Config{
+				Start:    "23:00",
+				Duration: time.Hour,
+				Every:    []string{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"},
+			},
+			expectedError: nil,
+		},
+		{
+			name: "every-monday-at-0000",
+			cfg: &Config{
+				Start:    "00:00",
+				Duration: 30 * time.Minute,
+				Every:    []string{"Monday"},
+			},
+			expectedError: nil,
+		},
+		{
+			name: "every-friday-and-sunday-at-0000-explicitly-enabled",
+			cfg: &Config{
+				Enabled:  &yes,
+				Start:    "08:00",
+				Duration: 8 * time.Hour,
+				Every:    []string{"Friday", "Sunday"},
+			},
+			expectedError: nil,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			err := scenario.cfg.ValidateAndSetDefaults()
+			if !errors.Is(err, scenario.expectedError) {
+				t.Errorf("expected %v, got %v", scenario.expectedError, err)
+			}
+		})
+	}
+}
+
+func TestConfig_IsUnderMaintenance(t *testing.T) {
+	yes, no := true, false
+	now := time.Now().UTC()
+	scenarios := []struct {
+		name     string
+		cfg      *Config
+		expected bool
+	}{
+		{
+			name: "disabled",
+			cfg: &Config{
+				Enabled: &no,
+			},
+			expected: false,
+		},
+		{
+			name: "under-maintenance-explicitly-enabled",
+			cfg: &Config{
+				Enabled:  &yes,
+				Start:    fmt.Sprintf("%02d:00", now.Hour()),
+				Duration: 2 * time.Hour,
+			},
+			expected: true,
+		},
+		{
+			name: "under-maintenance-starting-now-for-2h",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", now.Hour()),
+				Duration: 2 * time.Hour,
+			},
+			expected: true,
+		},
+		{
+			name: "under-maintenance-starting-now-for-8h",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", now.Hour()),
+				Duration: 8 * time.Hour,
+			},
+			expected: true,
+		},
+		{
+			name: "under-maintenance-starting-now-for-8h-explicit-days",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", now.Hour()),
+				Duration: 8 * time.Hour,
+				Every:    []string{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"},
+			},
+			expected: true,
+		},
+		{
+			name: "under-maintenance-starting-now-for-23h-explicit-days",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", now.Hour()),
+				Duration: 23 * time.Hour,
+				Every:    []string{"Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"},
+			},
+			expected: true,
+		},
+		{
+			name: "under-maintenance-starting-4h-ago-for-8h",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", normalizeHour(now.Hour()-4)),
+				Duration: 8 * time.Hour,
+			},
+			expected: true,
+		},
+		{
+			name: "under-maintenance-starting-22h-ago-for-23h",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", normalizeHour(now.Hour()-22)),
+				Duration: 23 * time.Hour,
+			},
+			expected: true,
+		},
+		{
+			name: "under-maintenance-starting-4h-ago-for-3h",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", normalizeHour(now.Hour()-4)),
+				Duration: 3 * time.Hour,
+			},
+			expected: false,
+		},
+		{
+			name: "under-maintenance-starting-5h-ago-for-1h",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", normalizeHour(now.Hour()-5)),
+				Duration: time.Hour,
+			},
+			expected: false,
+		},
+		{
+			name: "not-under-maintenance-today",
+			cfg: &Config{
+				Start:    fmt.Sprintf("%02d:00", now.Hour()),
+				Duration: time.Hour,
+				Every:    []string{now.Add(48 * time.Hour).Weekday().String()},
+			},
+			expected: false,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			t.Log(scenario.cfg.Start)
+			t.Log(now)
+			if err := scenario.cfg.ValidateAndSetDefaults(); err != nil {
+				t.Fatal("validation shouldn't have returned an error, got", err)
+			}
+			isUnderMaintenance := scenario.cfg.IsUnderMaintenance()
+			if isUnderMaintenance != scenario.expected {
+				t.Errorf("expected %v, got %v", scenario.expected, isUnderMaintenance)
+				t.Logf("start=%v; duration=%v; now=%v", scenario.cfg.Start, scenario.cfg.Duration, time.Now().UTC())
+			}
+		})
+	}
+}
+
+func normalizeHour(hour int) int {
+	if hour < 0 {
+		return hour + 24
+	}
+	return hour
+}

config/remote/remote.go

@@ -0,0 +1,39 @@
+package remote
+
+import (
+	"log"
+
+	"github.com/TwiN/gatus/v4/client"
+)
+
+// NOTICE: This is an experimental alpha feature and may be updated/removed in future versions.
+// For more information, see https://github.com/TwiN/gatus/issues/64
+
+type Config struct {
+	// Instances is a list of remote instances to retrieve endpoint statuses from.
+	Instances []Instance `yaml:"instances,omitempty"`
+
+	// ClientConfig is the configuration of the client used to communicate with the provider's target
+	ClientConfig *client.Config `yaml:"client,omitempty"`
+}
+
+type Instance struct {
+	EndpointPrefix string `yaml:"endpoint-prefix"`
+	URL            string `yaml:"url"`
+}
+
+func (c *Config) ValidateAndSetDefaults() error {
+	if c.ClientConfig == nil {
+		c.ClientConfig = client.GetDefaultConfig()
+	} else {
+		if err := c.ClientConfig.ValidateAndSetDefaults(); err != nil {
+			return err
+		}
+	}
+	if len(c.Instances) > 0 {
+		log.Println("WARNING: Your configuration is using 'remote', which is in alpha and may be updated/removed in future versions.")
+		log.Println("WARNING: See https://github.com/TwiN/gatus/issues/64 for more information")
+		log.Println("WARNING: This feature is a candidate for removal in future versions. Please comment on the issue above if you need this feature.")
+	}
+	return nil
+}

config/ui/ui.go

@@ -0,0 +1,88 @@
+package ui
+
+import (
+	"bytes"
+	"errors"
+	"html/template"
+
+	"github.com/TwiN/gatus/v4/web"
+)
+
+const (
+	defaultTitle       = "Health Dashboard | Gatus"
+	defaultDescription = "Gatus is an advanced automated status page that lets you monitor your applications and configure alerts to notify you if there's an issue"
+	defaultHeader      = "Health Status"
+	defaultLogo        = ""
+	defaultLink        = ""
+)
+
+var (
+	ErrButtonValidationFailed = errors.New("invalid button configuration: missing required name or link")
+)
+
+// Config is the configuration for the UI of Gatus
+type Config struct {
+	Title       string   `yaml:"title,omitempty"`       // Title of the page
+	Description string   `yaml:"description,omitempty"` // Meta description of the page
+	Header      string   `yaml:"header,omitempty"`      // Header is the text at the top of the page
+	Logo        string   `yaml:"logo,omitempty"`        // Logo to display on the page
+	Link        string   `yaml:"link,omitempty"`        // Link to open when clicking on the logo
+	Buttons     []Button `yaml:"buttons,omitempty"`     // Buttons to display below the header
+}
+
+// Button is the configuration for a button on the UI
+type Button struct {
+	Name string `yaml:"name,omitempty"` // Name is the text to display on the button
+	Link string `yaml:"link,omitempty"` // Link to open when the button is clicked.
+}
+
+// Validate validates the button configuration
+func (btn *Button) Validate() error {
+	if len(btn.Name) == 0 || len(btn.Link) == 0 {
+		return ErrButtonValidationFailed
+	}
+	return nil
+}
+
+// GetDefaultConfig returns a Config struct with the default values
+func GetDefaultConfig() *Config {
+	return &Config{
+		Title:       defaultTitle,
+		Description: defaultDescription,
+		Header:      defaultHeader,
+		Logo:        defaultLogo,
+		Link:        defaultLink,
+	}
+}
+
+// ValidateAndSetDefaults validates the UI configuration and sets the default values if necessary.
+func (cfg *Config) ValidateAndSetDefaults() error {
+	if len(cfg.Title) == 0 {
+		cfg.Title = defaultTitle
+	}
+	if len(cfg.Description) == 0 {
+		cfg.Description = defaultDescription
+	}
+	if len(cfg.Header) == 0 {
+		cfg.Header = defaultHeader
+	}
+	if len(cfg.Header) == 0 {
+		cfg.Header = defaultLink
+	}
+	for _, btn := range cfg.Buttons {
+		if err := btn.Validate(); err != nil {
+			return err
+		}
+	}
+	// Validate that the template works
+	t, err := template.ParseFS(static.FileSystem, static.IndexPath)
+	if err != nil {
+		return err
+	}
+	var buffer bytes.Buffer
+	err = t.Execute(&buffer, cfg)
+	if err != nil {
+		return err
+	}
+	return nil
+}

config/ui/ui_test.go

@@ -0,0 +1,77 @@
+package ui
+
+import (
+	"strconv"
+	"testing"
+)
+
+func TestConfig_ValidateAndSetDefaults(t *testing.T) {
+	cfg := &Config{
+		Title:       "",
+		Description: "",
+		Header:      "",
+		Logo:        "",
+		Link:        "",
+	}
+	if err := cfg.ValidateAndSetDefaults(); err != nil {
+		t.Error("expected no error, got", err.Error())
+	}
+	if cfg.Title != defaultTitle {
+		t.Errorf("expected title to be %s, got %s", defaultTitle, cfg.Title)
+	}
+	if cfg.Description != defaultDescription {
+		t.Errorf("expected description to be %s, got %s", defaultDescription, cfg.Description)
+	}
+	if cfg.Header != defaultHeader {
+		t.Errorf("expected header to be %s, got %s", defaultHeader, cfg.Header)
+	}
+}
+
+func TestButton_Validate(t *testing.T) {
+	scenarios := []struct {
+		Name, Link    string
+		ExpectedError error
+	}{
+		{
+			Name:          "",
+			Link:          "",
+			ExpectedError: ErrButtonValidationFailed,
+		},
+		{
+			Name:          "",
+			Link:          "link",
+			ExpectedError: ErrButtonValidationFailed,
+		},
+		{
+			Name:          "name",
+			Link:          "",
+			ExpectedError: ErrButtonValidationFailed,
+		},
+		{
+			Name:          "name",
+			Link:          "link",
+			ExpectedError: nil,
+		},
+	}
+	for i, scenario := range scenarios {
+		t.Run(strconv.Itoa(i)+"_"+scenario.Name+"_"+scenario.Link, func(t *testing.T) {
+			button := &Button{
+				Name: scenario.Name,
+				Link: scenario.Link,
+			}
+			if err := button.Validate(); err != scenario.ExpectedError {
+				t.Errorf("expected error %v, got %v", scenario.ExpectedError, err)
+			}
+		})
+	}
+}
+
+func TestGetDefaultConfig(t *testing.T) {
+	defaultConfig := GetDefaultConfig()
+	if defaultConfig.Title != defaultTitle {
+		t.Error("expected GetDefaultConfig() to return defaultTitle, got", defaultConfig.Title)
+	}
+	if defaultConfig.Logo != defaultLogo {
+		t.Error("expected GetDefaultConfig() to return defaultLogo, got", defaultConfig.Logo)
+	}
+}

config/web.go

@@ -1,63 +0,0 @@
-package config
-
-import (
-	"fmt"
-	"math"
-	"net/url"
-	"strings"
-)
-
-// webConfig is the structure which supports the configuration of the endpoint
-// which provides access to the web frontend
-type webConfig struct {
-	// Address to listen on (defaults to 0.0.0.0 specified by DefaultAddress)
-	Address string `yaml:"address"`
-
-	// Port to listen on (default to 8080 specified by DefaultPort)
-	Port int `yaml:"port"`
-
-	// ContextRoot set the root context for the web application
-	ContextRoot string `yaml:"context-root"`
-}
-
-// validateAndSetDefaults checks and sets the default values for fields that are not set
-func (web *webConfig) validateAndSetDefaults() {
-	// Validate the Address
-	if len(web.Address) == 0 {
-		web.Address = DefaultAddress
-	}
-	// Validate the Port
-	if web.Port == 0 {
-		web.Port = DefaultPort
-	} else if web.Port < 0 || web.Port > math.MaxUint16 {
-		panic(fmt.Sprintf("invalid port: value should be between %d and %d", 0, math.MaxUint16))
-	}
-	// Validate the ContextRoot
-	if len(web.ContextRoot) == 0 {
-		web.ContextRoot = DefaultContextRoot
-	} else {
-		trimmedContextRoot := strings.Trim(web.ContextRoot, "/")
-		if len(trimmedContextRoot) == 0 {
-			web.ContextRoot = DefaultContextRoot
-			return
-		}
-		rootContextURL, err := url.Parse(trimmedContextRoot)
-		if err != nil {
-			panic("invalid context root:" + err.Error())
-		}
-		if rootContextURL.Path != trimmedContextRoot {
-			panic("invalid context root: too complex")
-		}
-		web.ContextRoot = "/" + strings.Trim(rootContextURL.Path, "/") + "/"
-	}
-}
-
-// SocketAddress returns the combination of the Address and the Port
-func (web *webConfig) SocketAddress() string {
-	return fmt.Sprintf("%s:%d", web.Address, web.Port)
-}
-
-// PrependWithContextRoot appends the given path to the ContextRoot
-func (web *webConfig) PrependWithContextRoot(path string) string {
-	return web.ContextRoot + strings.Trim(path, "/")
-}

config/web/web.go

@@ -0,0 +1,49 @@
+package web
+
+import (
+	"fmt"
+	"math"
+)
+
+const (
+	// DefaultAddress is the default address the application will bind to
+	DefaultAddress = "0.0.0.0"
+
+	// DefaultPort is the default port the application will listen on
+	DefaultPort = 8080
+)
+
+// Config is the structure which supports the configuration of the endpoint
+// which provides access to the web frontend
+type Config struct {
+	// Address to listen on (defaults to 0.0.0.0 specified by DefaultAddress)
+	Address string `yaml:"address"`
+
+	// Port to listen on (default to 8080 specified by DefaultPort)
+	Port int `yaml:"port"`
+}
+
+// GetDefaultConfig returns a Config struct with the default values
+func GetDefaultConfig() *Config {
+	return &Config{Address: DefaultAddress, Port: DefaultPort}
+}
+
+// ValidateAndSetDefaults validates the web configuration and sets the default values if necessary.
+func (web *Config) ValidateAndSetDefaults() error {
+	// Validate the Address
+	if len(web.Address) == 0 {
+		web.Address = DefaultAddress
+	}
+	// Validate the Port
+	if web.Port == 0 {
+		web.Port = DefaultPort
+	} else if web.Port < 0 || web.Port > math.MaxUint16 {
+		return fmt.Errorf("invalid port: value should be between %d and %d", 0, math.MaxUint16)
+	}
+	return nil
+}
+
+// SocketAddress returns the combination of the Address and the Port
+func (web *Config) SocketAddress() string {
+	return fmt.Sprintf("%s:%d", web.Address, web.Port)
+}

config/web/web_test.go

@@ -0,0 +1,65 @@
+package web
+
+import (
+	"testing"
+)
+
+func TestGetDefaultConfig(t *testing.T) {
+	defaultConfig := GetDefaultConfig()
+	if defaultConfig.Port != DefaultPort {
+		t.Error("expected default config to have the default port")
+	}
+	if defaultConfig.Address != DefaultAddress {
+		t.Error("expected default config to have the default address")
+	}
+}
+
+func TestConfig_ValidateAndSetDefaults(t *testing.T) {
+	scenarios := []struct {
+		name            string
+		cfg             *Config
+		expectedAddress string
+		expectedPort    int
+		expectedErr     bool
+	}{
+		{
+			name:            "no-explicit-config",
+			cfg:             &Config{},
+			expectedAddress: "0.0.0.0",
+			expectedPort:    8080,
+			expectedErr:     false,
+		},
+		{
+			name:        "invalid-port",
+			cfg:         &Config{Port: 100000000},
+			expectedErr: true,
+		},
+	}
+	for _, scenario := range scenarios {
+		t.Run(scenario.name, func(t *testing.T) {
+			err := scenario.cfg.ValidateAndSetDefaults()
+			if (err != nil) != scenario.expectedErr {
+				t.Errorf("expected the existence of an error to be %v, got %v", scenario.expectedErr, err)
+				return
+			}
+			if !scenario.expectedErr {
+				if scenario.cfg.Port != scenario.expectedPort {
+					t.Errorf("expected port to be %d, got %d", scenario.expectedPort, scenario.cfg.Port)
+				}
+				if scenario.cfg.Address != scenario.expectedAddress {
+					t.Errorf("expected address to be %s, got %s", scenario.expectedAddress, scenario.cfg.Address)
+				}
+			}
+		})
+	}
+}
+
+func TestConfig_SocketAddress(t *testing.T) {
+	web := &Config{
+		Address: "0.0.0.0",
+		Port:    8081,
+	}
+	if web.SocketAddress() != "0.0.0.0:8081" {
+		t.Errorf("expected %s, got %s", "0.0.0.0:8081", web.SocketAddress())
+	}
+}

config/web_test.go

@@ -1,99 +0,0 @@
-package config
-
-import (
-	"fmt"
-	"testing"
-)
-
-func TestWebConfig_SocketAddress(t *testing.T) {
-	web := &webConfig{
-		Address: "0.0.0.0",
-		Port:    8081,
-	}
-	if web.SocketAddress() != "0.0.0.0:8081" {
-		t.Errorf("expected %s, got %s", "0.0.0.0:8081", web.SocketAddress())
-	}
-}
-
-func TestWebConfig_PrependWithContextRoot(t *testing.T) {
-	web := &webConfig{ContextRoot: "/status/"}
-	if result := web.PrependWithContextRoot("/api/v1/results"); result != "/status/api/v1/results" {
-		t.Errorf("expected %s, got %s", "/status/api/v1/results", result)
-	}
-	if result := web.PrependWithContextRoot("/health"); result != "/status/health" {
-		t.Errorf("expected %s, got %s", "/status/health", result)
-	}
-	if result := web.PrependWithContextRoot("/health/"); result != "/status/health" {
-		t.Errorf("expected %s, got %s", "/status/health", result)
-	}
-}
-
-// validContextRootTest specifies all test case which should end up in
-// a valid context root used to bind the web interface to
-var validContextRootTests = []struct {
-	name         string
-	path         string
-	expectedPath string
-}{
-	{"Empty", "", "/"},
-	{"/", "/", "/"},
-	{"///", "///", "/"},
-	{"Single character 'a'", "a", "/a/"},
-	{"Slash at the beginning", "/status", "/status/"},
-	{"Slashes at start and end", "/status/", "/status/"},
-	{"Multiple slashes at start", "//status", "/status/"},
-	{"Multiple slashes at start and end", "///status////", "/status/"},
-	{"Contains '@' in path'", "me@/status/gatus", "/me@/status/gatus/"},
-	{"Nested context with trailing slash", "/status/gatus/", "/status/gatus/"},
-	{"Nested context without trailing slash", "/status/gatus/system", "/status/gatus/system/"},
-}
-
-func TestWebConfig_ValidContextRoots(t *testing.T) {
-	for idx, test := range validContextRootTests {
-		t.Run(fmt.Sprintf("%d: %s", idx, test.name), func(t *testing.T) {
-			expectValidResultForContextRoot(t, test.path, test.expectedPath)
-		})
-	}
-}
-
-func expectValidResultForContextRoot(t *testing.T, path string, expected string) {
-	web := &webConfig{
-		ContextRoot: path,
-	}
-	web.validateAndSetDefaults()
-	if web.ContextRoot != expected {
-		t.Errorf("expected %s, got %s", expected, web.ContextRoot)
-	}
-}
-
-// invalidContextRootTests contains all tests for context root which are
-// expected to fail and stop program execution
-var invalidContextRootTests = []struct {
-	name string
-	path string
-}{
-	{"Only a fragment identifier", "#"},
-	{"Invalid character in path", "/invalid" + string([]byte{0x7F})},
-	{"Starts with protocol", "http://status/gatus"},
-	{"Path with fragment", "/status/gatus#here"},
-	{"Starts with '://'", "://status"},
-	{"Contains query parameter", "/status/h?ello=world"},
-	{"Contains '?'", "/status?"},
-}
-
-func TestWebConfig_InvalidContextRoots(t *testing.T) {
-	for idx, test := range invalidContextRootTests {
-		t.Run(fmt.Sprintf("%d: %s", idx, test.name), func(t *testing.T) {
-			expectInvalidResultForContextRoot(t, test.path)
-		})
-	}
-}
-
-func expectInvalidResultForContextRoot(t *testing.T, path string) {
-	defer func() { recover() }()
-
-	web := &webConfig{ContextRoot: path}
-	web.validateAndSetDefaults()
-
-	t.Fatal(fmt.Sprintf("Should've panicked because the configuration specifies an invalid context root: %s", path))
-}