new argument to alert the channel on critical events

.github/workflows/lint.yml

@@ -10,7 +10,11 @@ jobs:
       matrix:
         os: [ubuntu-latest]
     steps:
-    - name: Checkout code
-      uses: actions/checkout@v2
-    - name: Run golangci-lint
-      uses: actions-contrib/golangci-lint@v1
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.17
+      - uses: actions/checkout@v3
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v3
+        with:
+          version: latest

README.md

@@ -36,6 +36,7 @@ Available Commands:
   version     Print the version number of this plugin
 
 Flags:
+  -a, --alert-on-critical             The Slack notification will alert the channel with @channel
   -c, --channel string                The channel to post messages to (default "#general")
   -t, --description-template string   The Slack notification output template, in Golang text/template format (default "{{ .Check.Output }}")
   -h, --help                          help for sensu-slack-handler
@@ -53,6 +54,7 @@ Flags:
 |--username             |SLACK_USERNAME             |
 |--icon-url             |SLACK_ICON_URL             |
 |--description-template |SLACK_DESCRIPTION_TEMPLATE |
+|--alert-on-critical    |SLACK_ALERT_ON_CRITICAL    |
 
 
 **Security Note:** Care should be taken to not expose the webhook URL for this handler by specifying it

main.go

@@ -19,6 +19,7 @@ type HandlerConfig struct {
 	slackUsername            string
 	slackIconURL             string
 	slackDescriptionTemplate string
+	slackAlertCritical       bool
 }
 
 const (
@@ -27,11 +28,13 @@ const (
 	username            = "username"
 	iconURL             = "icon-url"
 	descriptionTemplate = "description-template"
+	alertCritical       = "alert-on-critical"
 
-	defaultChannel  = "#general"
-	defaultIconURL  = "https://www.sensu.io/img/sensu-logo.png"
-	defaultUsername = "sensu"
-	defaultTemplate = "{{ .Check.Output }}"
+	defaultChannel       = "#general"
+	defaultIconURL       = "https://www.sensu.io/img/sensu-logo.png"
+	defaultUsername      = "sensu"
+	defaultTemplate      = "{{ .Check.Output }}"
+	defaultAlert    bool = false
 )
 
 var (
@@ -89,6 +92,15 @@ var (
 			Usage:     "The Slack notification output template, in Golang text/template format",
 			Value:     &config.slackDescriptionTemplate,
 		},
+		{
+			Path:      alertCritical,
+			Env:       "SLACK_ALERT_ON_CRITICAL",
+			Argument:  alertCritical,
+			Shorthand: "a",
+			Default:   defaultAlert,
+			Usage:     "The Slack notification will alert the channel with @channel",
+			Value:     &config.slackAlertCritical,
+		},
 	}
 )
 
@@ -164,7 +176,11 @@ func messageStatus(event *corev2.Event) string {
 	case 0:
 		return "Resolved"
 	case 2:
-		return "Critical"
+		if config.slackAlertCritical {
+			return "<!channel> Critical"
+		} else {
+			return "Critical"
+		}
 	default:
 		return "Warning"
 	}
@@ -175,6 +191,7 @@ func messageAttachment(event *corev2.Event) *slack.Attachment {
 	if err != nil {
 		fmt.Printf("%s: Error processing template: %s", config.PluginConfig.Name, err)
 	}
+
 	description = strings.Replace(description, `\n`, "\n", -1)
 	attachment := &slack.Attachment{
 		Title:    "Description",