fix(alertmanager): make templater reusable

Signed-off-by: alkur-gh <20610261+alkur-gh@users.noreply.github.com>

Author: alkur-gh

pkg/services/alertmanager.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"maps"
 	"net/http"
 	"net/url"
 	"strings"
@@ -100,12 +101,12 @@ func (n AlertmanagerNotification) GetTemplater(name string, f texttemplate.FuncM
 			return fmt.Errorf("at least one label pair required")
 		}
 
-		notification.Alertmanager.Labels = n.Labels
+		notification.Alertmanager.Labels = maps.Clone(n.Labels)
 		if err := notification.Alertmanager.parseLabels(name, f, vars); err != nil {
 			return err
 		}
 		if len(n.Annotations) > 0 {
-			notification.Alertmanager.Annotations = n.Annotations
+			notification.Alertmanager.Annotations = maps.Clone(n.Annotations)
 			if err := notification.Alertmanager.parseAnnotations(name, f, vars); err != nil {
 				return err
 			}

pkg/services/alertmanager_test.go

@@ -1,6 +1,7 @@
 package services
 
 import (
+	"fmt"
 	"testing"
 	"text/template"
 
@@ -159,3 +160,46 @@ func Test_AlertManagerNoLabels(t *testing.T) {
 	err := svc.Send(n, Destination{})
 	assert.EqualError(t, err, "alertmanager at least one label pair required")
 }
+
+func Test_AlertManagerReusableTemplater(t *testing.T) {
+	n := Notification{
+		Alertmanager: &AlertmanagerNotification{
+			Labels: map[string]string{
+				"alertname": "App_Deployed",
+				"appname":   "{{.app.metadata.name}}",
+			},
+			Annotations: map[string]string{
+				"appname": "{{.app.metadata.name}}",
+			},
+		},
+	}
+
+	templater, err := n.GetTemplater("", template.FuncMap{})
+	if !assert.NoError(t, err) {
+		return
+	}
+
+	for i := 0; i < 2; i++ {
+		name := fmt.Sprintf("argocd-notifications-%d", i)
+		var notification Notification
+		err = templater(&notification, map[string]interface{}{
+			"app": map[string]interface{}{
+				"metadata": map[string]interface{}{
+					"name": name,
+				},
+				"spec": map[string]interface{}{
+					"source": map[string]interface{}{
+						"repoURL": "https://github.com/argoproj-labs/argocd-notifications.git",
+					},
+				},
+			},
+		})
+		if !assert.NoError(t, err) {
+			return
+		}
+
+		assert.Equal(t, "App_Deployed", notification.Alertmanager.Labels["alertname"])
+		assert.Equal(t, name, notification.Alertmanager.Labels["appname"])
+		assert.Equal(t, name, notification.Alertmanager.Annotations["appname"])
+	}
+}