feat: Implement announcements (#1204)

* feat: Implement announcements

Fixes #1203

* Remove unnecessary code

* Fix new announcement test

* Update web/app/src/views/Home.vue

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* Remove useless garbage

* Require announcement timestamp

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

config/announcement/announcement.go

@@ -0,0 +1,94 @@
+package announcement
+
+import (
+	"errors"
+	"sort"
+	"time"
+)
+
+const (
+	// TypeOutage represents a service outage
+	TypeOutage = "outage"
+
+	// TypeWarning represents a warning or potential issue
+	TypeWarning = "warning"
+
+	// TypeInformation represents general information
+	TypeInformation = "information"
+
+	// TypeOperational represents operational status or resolved issues
+	TypeOperational = "operational"
+
+	// TypeNone represents no specific type (default)
+	TypeNone = "none"
+)
+
+var (
+	// ErrInvalidAnnouncementType is returned when an invalid announcement type is specified
+	ErrInvalidAnnouncementType = errors.New("invalid announcement type")
+
+	// ErrEmptyMessage is returned when an announcement has an empty message
+	ErrEmptyMessage = errors.New("announcement message cannot be empty")
+
+	// ErrMissingTimestamp is returned when an announcement has an empty timestamp
+	ErrMissingTimestamp = errors.New("announcement timestamp must be set")
+
+	// validTypes contains all valid announcement types
+	validTypes = map[string]bool{
+		TypeOutage:      true,
+		TypeWarning:     true,
+		TypeInformation: true,
+		TypeOperational: true,
+		TypeNone:        true,
+	}
+)
+
+// Announcement represents a system-wide announcement
+type Announcement struct {
+	// Timestamp is the UTC timestamp when the announcement was made
+	Timestamp time.Time `yaml:"timestamp" json:"timestamp"`
+
+	// Type is the type of announcement (outage, warning, information, operational, none)
+	Type string `yaml:"type" json:"type"`
+
+	// Message is the user-facing text describing the announcement
+	Message string `yaml:"message" json:"message"`
+}
+
+// ValidateAndSetDefaults validates the announcement and sets default values if necessary
+func (a *Announcement) ValidateAndSetDefaults() error {
+	// Validate message
+	if a.Message == "" {
+		return ErrEmptyMessage
+	}
+	// Set default type if empty
+	if a.Type == "" {
+		a.Type = TypeNone
+	}
+	// Validate type
+	if !validTypes[a.Type] {
+		return ErrInvalidAnnouncementType
+	}
+	// If timestamp is zero, return an error
+	if a.Timestamp.IsZero() {
+		return ErrMissingTimestamp
+	}
+	return nil
+}
+
+// SortByTimestamp sorts a slice of announcements by timestamp in descending order (newest first)
+func SortByTimestamp(announcements []*Announcement) {
+	sort.Slice(announcements, func(i, j int) bool {
+		return announcements[i].Timestamp.After(announcements[j].Timestamp)
+	})
+}
+
+// ValidateAndSetDefaults validates a slice of announcements and sets defaults
+func ValidateAndSetDefaults(announcements []*Announcement) error {
+	for _, announcement := range announcements {
+		if err := announcement.ValidateAndSetDefaults(); err != nil {
+			return err
+		}
+	}
+	return nil
+}

config/config.go

@@ -14,6 +14,7 @@ import (
 	"github.com/TwiN/gatus/v5/alerting"
 	"github.com/TwiN/gatus/v5/alerting/alert"
 	"github.com/TwiN/gatus/v5/alerting/provider"
+	"github.com/TwiN/gatus/v5/config/announcement"
 	"github.com/TwiN/gatus/v5/config/connectivity"
 	"github.com/TwiN/gatus/v5/config/endpoint"
 	"github.com/TwiN/gatus/v5/config/maintenance"
@@ -99,6 +100,9 @@ type Config struct {
 	// Connectivity is the configuration for connectivity
 	Connectivity *connectivity.Config `yaml:"connectivity,omitempty"`
 
+	// Announcements is the list of system-wide announcements
+	Announcements []*announcement.Announcement `yaml:"announcements,omitempty"`
+
 	configPath      string    // path to the file or directory from which config was loaded
 	lastFileModTime time.Time // last modification time
 }
@@ -302,6 +306,9 @@ func parseAndValidateConfigBytes(yamlBytes []byte) (config *Config, err error) {
 		if err := validateConnectivityConfig(config); err != nil {
 			return nil, err
 		}
+		if err := validateAnnouncementsConfig(config); err != nil {
+			return nil, err
+		}
 		// Cross-config changes
 		config.UI.MaximumNumberOfResults = config.Storage.MaximumNumberOfResults
 	}
@@ -315,6 +322,17 @@ func validateConnectivityConfig(config *Config) error {
 	return nil
 }
 
+func validateAnnouncementsConfig(config *Config) error {
+	if config.Announcements != nil {
+		if err := announcement.ValidateAndSetDefaults(config.Announcements); err != nil {
+			return err
+		}
+		// Sort announcements by timestamp (newest first) for API response
+		announcement.SortByTimestamp(config.Announcements)
+	}
+	return nil
+}
+
 func validateRemoteConfig(config *Config) error {
 	if config.Remote != nil {
 		if err := config.Remote.ValidateAndSetDefaults(); err != nil {