Fix potential panic

Add basic duration comparison

.dockerignore

@@ -1,3 +1,5 @@
 example
+Dockerfile
 .github
 .idea
+.git

Dockerfile

@@ -1,9 +1,9 @@
 # Build the go application into a binary
 FROM golang:alpine as builder
-WORKDIR /app
-ADD . ./
-RUN CGO_ENABLED=0 GOOS=linux go build -mod vendor -a -installsuffix cgo -o gatus .
 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 Tests inside docker image if you don't have a configured go environment
 #RUN apk update && apk add --virtual build-dependencies build-base gcc
@@ -17,4 +17,4 @@ 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}
-ENTRYPOINT ["/gatus"]
+ENTRYPOINT ["/gatus"]

README.md

@@ -24,9 +24,9 @@ core applications: https://status.twinnation.org/
     - [Functions](#functions)
   - [Alerting](#alerting)
     - [Configuring Slack alerts](#configuring-slack-alerts)
-    - [Configuring Mattermost alerts](#configuring-mattermost-alerts)
     - [Configuring PagerDuty alerts](#configuring-pagerduty-alerts)
     - [Configuring Twilio alerts](#configuring-twilio-alerts)
+    - [Configuring Mattermost alerts](#configuring-mattermost-alerts)
     - [Configuring custom alerts](#configuring-custom-alerts)
   - [Kubernetes (ALPHA)](#kubernetes-alpha)
     - [Auto Discovery](#auto-discovery)
@@ -103,7 +103,7 @@ Note that you can also add environment variables in the configuration file (i.e.
 | `services[].graphql`                     | Whether to wrap the body in a query param (`{"query":"$body"}`)               | `false`        |
 | `services[].body`                        | Request body                                                                  | `""`           |
 | `services[].headers`                     | Request headers                                                               | `{}`           |
-| `services[].alerts[].type`               | Type of alert. Valid types: `slack`, `pagerduty`, `twilio`, `custom`, `mattermost` | Required `""`  |
+| `services[].alerts[].type`               | Type of alert. Valid types: `slack`, `pagerduty`, `twilio`, `mattermost`, `custom` | Required `""`  |
 | `services[].alerts[].enabled`            | Whether to enable the alert                                                   | `false`        |
 | `services[].alerts[].failure-threshold`  | Number of failures in a row needed before triggering the alert                | `3`            |
 | `services[].alerts[].success-threshold`  | Number of successes in a row before an ongoing incident is marked as resolved | `2`            |
@@ -112,9 +112,6 @@ Note that you can also add environment variables in the configuration file (i.e.
 | `alerting`                               | Configuration for alerting                                                    | `{}`           |
 | `alerting.slack`                         | Configuration for alerts of type `slack`                                      | `{}`           |
 | `alerting.slack.webhook-url`             | Slack Webhook URL                                                             | Required `""`  |
-| `alerting.mattermost`                    | Configuration for alerts of type `mattermost`                                 | `{}`           |
-| `alerting.mattermost.webhook-url`        | Mattermost Webhook URL                                                        | Required `""`  |
-| `alerting.mattermost.insecure`           | Whether to skip verifying the server's certificate chain and host name        | `false`        |
 | `alerting.pagerduty`                     | Configuration for alerts of type `pagerduty`                                  | `{}`           |
 | `alerting.pagerduty.integration-key`     | PagerDuty Events API v2 integration key.                                      | Required `""`  |
 | `alerting.twilio`                        | Settings for alerts of type `twilio`                                          | `{}`           |
@@ -122,6 +119,9 @@ Note that you can also add environment variables in the configuration file (i.e.
 | `alerting.twilio.token`                  | Twilio auth token                                                             | Required `""`  |
 | `alerting.twilio.from`                   | Number to send Twilio alerts from                                             | Required `""`  |
 | `alerting.twilio.to`                     | Number to send twilio alerts to                                               | Required `""`  |
+| `alerting.mattermost`                    | Configuration for alerts of type `mattermost`                                 | `{}`           |
+| `alerting.mattermost.webhook-url`        | Mattermost Webhook URL                                                        | Required `""`  |
+| `alerting.mattermost.insecure`           | Whether to skip verifying the server's certificate chain and host name        | `false`        |
 | `alerting.custom`                        | Configuration for custom actions on failure or alerts                         | `{}`           |
 | `alerting.custom.url`                    | Custom alerting request url                                                   | Required `""`  |
 | `alerting.custom.method`                 | Request method                                                                | `GET`          |
@@ -157,17 +157,19 @@ Here are some examples of conditions you can use:
 | `len([BODY].data) < 5`       | Array at JSONPath `$.data` has less than 5 elements     | `{"data":[{"id":1}]}`      |  |
 | `len([BODY].name) == 8`      | String at JSONPath `$.name` has a length of 8           | `{"name":"john.doe"}`      | `{"name":"bob"}` |
 | `[BODY].name == pat(john*)`  | String at JSONPath `$.name` matches pattern `john*`     | `{"name":"john.doe"}`      | `{"name":"bob"}` |
+| `[CERTIFICATE_EXPIRATION] > 48h` | Certificate expiration is more than 48h away        | 49h, 50h, 123h             | 1h, 24h, ... |
 
 
 #### Placeholders
 
-| Placeholder             | Description                                             | Example of resolved value |
-|:----------------------- |:------------------------------------------------------- |:------------------------- |
-| `[STATUS]`              | Resolves into the HTTP status of the request            | 404
-| `[RESPONSE_TIME]`       | Resolves into the response time the request took, in ms | 10
-| `[IP]`                  | Resolves into the IP of the target host                 | 192.168.0.232
-| `[BODY]`                | Resolves into the response body. Supports JSONPath.     | `{"name":"john.doe"}`
-| `[CONNECTED]`           | Resolves into whether a connection could be established | `true`
+| Placeholder                | Description                                                     | Example of resolved value |
+|:-------------------------- |:--------------------------------------------------------------- |:------------------------- |
+| `[STATUS]`                 | Resolves into the HTTP status of the request                    | 404
+| `[RESPONSE_TIME]`          | Resolves into the response time the request took, in ms         | 10
+| `[IP]`                     | Resolves into the IP of the target host                         | 192.168.0.232
+| `[BODY]`                   | Resolves into the response body. Supports JSONPath.             | `{"name":"john.doe"}`
+| `[CONNECTED]`              | Resolves into whether a connection could be established         | `true`
+| `[CERTIFICATE_EXPIRATION]` | Resolves into the duration before certificate expiration        | `24h`, `48h`, 0 (if not using HTTPS)
 
 
 #### Functions
@@ -214,37 +216,6 @@ Here's an example of what the notifications look like:
 ![Slack notifications](.github/assets/slack-alerts.png)
 
 
-#### Configuring Mattermost alerts
-
-```yaml
-alerting:
-  mattermost: 
-    webhook-url: "http://**********/hooks/**********"
-    insecure: true
-services:
-  - name: twinnation
-    url: "https://twinnation.org/health"
-    interval: 30s
-    alerts:
-      - type: mattermost
-        enabled: true
-        description: "healthcheck failed 3 times in a row"
-        send-on-resolved: true
-      - type: mattermost
-        enabled: true
-        failure-threshold: 5
-        description: "healthcheck failed 5 times in a row"
-        send-on-resolved: true
-    conditions:
-      - "[STATUS] == 200"
-      - "[BODY].status == UP"
-      - "[RESPONSE_TIME] < 300"
-```
-
-Here's an example of what the notifications look like:
-
-![Mattermost notifications](.github/assets/mattermost-alerts.png)
-
 #### Configuring PagerDuty alerts
 
 It is highly recommended to set `services[].alerts[].send-on-resolved` to `true` for alerts 
@@ -300,6 +271,33 @@ services:
 ```
 
 
+#### Configuring Mattermost alerts
+
+```yaml
+alerting:
+  mattermost: 
+    webhook-url: "http://**********/hooks/**********"
+    insecure: true
+services:
+  - name: twinnation
+    url: "https://twinnation.org/health"
+    interval: 30s
+    alerts:
+      - type: mattermost
+        enabled: true
+        description: "healthcheck failed 3 times in a row"
+        send-on-resolved: true
+    conditions:
+      - "[STATUS] == 200"
+      - "[BODY].status == UP"
+      - "[RESPONSE_TIME] < 300"
+```
+
+Here's an example of what the notifications look like:
+
+![Mattermost notifications](.github/assets/mattermost-alerts.png)
+
+
 #### Configuring custom alerts
 
 While they're called alerts, you can use this feature to call anything. 

core/condition.go

@@ -2,11 +2,13 @@ package core
 
 import (
 	"fmt"
-	"github.com/TwinProduction/gatus/jsonpath"
-	"github.com/TwinProduction/gatus/pattern"
 	"log"
 	"strconv"
 	"strings"
+	"time"
+
+	"github.com/TwinProduction/gatus/jsonpath"
+	"github.com/TwinProduction/gatus/pattern"
 )
 
 const (
@@ -35,6 +37,11 @@ const (
 	// Values that could replace the placeholder: true, false
 	ConnectedPlaceHolder = "[CONNECTED]"
 
+	// CertificateExpirationPlaceholder is a placeholder for the duration before certificate expiration, in milliseconds.
+	//
+	// Values that could replace the placeholder: 4461677039 (~52 days)
+	CertificateExpirationPlaceholder = "[CERTIFICATE_EXPIRATION]"
+
 	// LengthFunctionPrefix is the prefix for the length function
 	LengthFunctionPrefix = "len("
 
@@ -142,6 +149,8 @@ func sanitizeAndResolve(list []string, result *Result) []string {
 			element = body
 		case ConnectedPlaceHolder:
 			element = strconv.FormatBool(result.Connected)
+		case CertificateExpirationPlaceholder:
+			element = strconv.FormatInt(int64(result.CertificateExpiration.Milliseconds()), 10)
 		default:
 			// if contains the BodyPlaceHolder, then evaluate json path
 			if strings.Contains(element, BodyPlaceHolder) {
@@ -174,11 +183,13 @@ func sanitizeAndResolve(list []string, result *Result) []string {
 	return sanitizedList
 }
 
-func sanitizeAndResolveNumerical(list []string, result *Result) []int {
-	var sanitizedNumbers []int
+func sanitizeAndResolveNumerical(list []string, result *Result) []int64 {
+	var sanitizedNumbers []int64
 	sanitizedList := sanitizeAndResolve(list, result)
 	for _, element := range sanitizedList {
-		if number, err := strconv.Atoi(element); err != nil {
+		if duration, err := time.ParseDuration(element); duration != 0 && err == nil {
+			sanitizedNumbers = append(sanitizedNumbers, duration.Milliseconds())
+		} else if number, err := strconv.ParseInt(element, 10, 64); err != nil {
 			// Default to 0 if the string couldn't be converted to an integer
 			sanitizedNumbers = append(sanitizedNumbers, 0)
 		} else {

core/condition_test.go

@@ -1,6 +1,7 @@
 package core
 
 import (
+	"strconv"
 	"testing"
 	"time"
 )
@@ -59,7 +60,27 @@ func TestCondition_evaluateWithResponseTimeUsingLessThan(t *testing.T) {
 	}
 }
 
+func TestCondition_evaluateWithResponseTimeUsingLessThanDuration(t *testing.T) {
+	condition := Condition("[RESPONSE_TIME] < 1s")
+	result := &Result{Duration: time.Millisecond * 50}
+	condition.evaluate(result)
+	if !result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a success", condition)
+	}
+}
+
+func TestCondition_evaluateWithResponseTimeUsingLessThanInvalid(t *testing.T) {
+	condition := Condition("[RESPONSE_TIME] < potato")
+	result := &Result{Duration: time.Millisecond * 50}
+	condition.evaluate(result)
+	if result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have failed because the condition has an invalid numerical value that should've automatically resolved to 0", condition)
+	}
+}
+
 func TestCondition_evaluateWithResponseTimeUsingGreaterThan(t *testing.T) {
+	// Not exactly sure why you'd want to have a condition that checks if the response time is too fast,
+	// but hey, who am I to judge?
 	condition := Condition("[RESPONSE_TIME] > 500")
 	result := &Result{Duration: time.Millisecond * 750}
 	condition.evaluate(result)
@@ -68,6 +89,15 @@ func TestCondition_evaluateWithResponseTimeUsingGreaterThan(t *testing.T) {
 	}
 }
 
+func TestCondition_evaluateWithResponseTimeUsingGreaterThanDuration(t *testing.T) {
+	condition := Condition("[RESPONSE_TIME] > 1s")
+	result := &Result{Duration: time.Second * 2}
+	condition.evaluate(result)
+	if !result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a success", condition)
+	}
+}
+
 func TestCondition_evaluateWithResponseTimeUsingGreaterThanOrEqualTo(t *testing.T) {
 	condition := Condition("[RESPONSE_TIME] >= 500")
 	result := &Result{Duration: time.Millisecond * 500}
@@ -309,3 +339,50 @@ func TestCondition_evaluateWithConnectedFailure(t *testing.T) {
 		t.Errorf("Condition '%s' should have been a failure", condition)
 	}
 }
+
+func TestCondition_evaluateWithUnsetCertificateExpiration(t *testing.T) {
+	condition := Condition("[CERTIFICATE_EXPIRATION] == 0")
+	result := &Result{}
+	condition.evaluate(result)
+	if !result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a success", condition)
+	}
+}
+
+func TestCondition_evaluateWithCertificateExpirationGreaterThanNumerical(t *testing.T) {
+	acceptable := (time.Hour * 24 * 28).Milliseconds()
+	condition := Condition("[CERTIFICATE_EXPIRATION] > " + strconv.FormatInt(acceptable, 10))
+	result := &Result{CertificateExpiration: time.Hour * 24 * 60}
+	condition.evaluate(result)
+	if !result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a success", condition)
+	}
+}
+
+func TestCondition_evaluateWithCertificateExpirationGreaterThanNumericalFailure(t *testing.T) {
+	acceptable := (time.Hour * 24 * 28).Milliseconds()
+	condition := Condition("[CERTIFICATE_EXPIRATION] > " + strconv.FormatInt(acceptable, 10))
+	result := &Result{CertificateExpiration: time.Hour * 24 * 14}
+	condition.evaluate(result)
+	if result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a failure", condition)
+	}
+}
+
+func TestCondition_evaluateWithCertificateExpirationGreaterThanDuration(t *testing.T) {
+	condition := Condition("[CERTIFICATE_EXPIRATION] > 12h")
+	result := &Result{CertificateExpiration: 24 * time.Hour}
+	condition.evaluate(result)
+	if !result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a success", condition)
+	}
+}
+
+func TestCondition_evaluateWithCertificateExpirationGreaterThanDurationFailure(t *testing.T) {
+	condition := Condition("[CERTIFICATE_EXPIRATION] > 48h")
+	result := &Result{CertificateExpiration: 24 * time.Hour}
+	condition.evaluate(result)
+	if result.ConditionResults[0].Success {
+		t.Errorf("Condition '%s' should have been a failure", condition)
+	}
+}

core/service.go

@@ -169,6 +169,10 @@ func (service *Service) call(result *Result) {
 			result.Errors = append(result.Errors, err.Error())
 			return
 		}
+		if response.TLS != nil && len(response.TLS.PeerCertificates) > 0 {
+			certificate := response.TLS.PeerCertificates[0]
+			result.CertificateExpiration = certificate.NotAfter.Sub(time.Now())
+		}
 		result.HTTPStatus = response.StatusCode
 		result.Connected = response.StatusCode > 0
 		result.Body, err = ioutil.ReadAll(response.Body)

core/types.go

@@ -45,6 +45,9 @@ type Result struct {
 
 	// Timestamp when the request was sent
 	Timestamp time.Time `json:"timestamp"`
+
+	// CertificateExpiration is the duration before the certificate expires
+	CertificateExpiration time.Duration `json:"certificate-expiration,omitempty"`
 }
 
 // ConditionResult result of a Condition