Alerting: Fix Slack push notifications (#52391)

This commit fixes push notifications for Slack which used to show "This content cannot be displayed". The text field is shown in both the message and the push notification.

pkg/services/ngalert/notifier/channels/slack.go

@@ -166,6 +166,7 @@ func NewSlackNotifier(config *SlackConfig,
 // slackMessage is the slackMessage for sending a slack notification.
 type slackMessage struct {
 	Channel     string                   `json:"channel,omitempty"`
+	Text        string                   `json:"text,omitempty"`
 	Username    string                   `json:"username,omitempty"`
 	IconEmoji   string                   `json:"icon_emoji,omitempty"`
 	IconURL     string                   `json:"icon_url,omitempty"`
@@ -299,6 +300,7 @@ func (sn *SlackNotifier) buildSlackMessage(ctx context.Context, alrts []*types.A
 
 	req := &slackMessage{
 		Channel:   tmpl(sn.Recipient),
+		Text:      tmpl(sn.Title),
 		Username:  tmpl(sn.Username),
 		IconEmoji: tmpl(sn.IconEmoji),
 		IconURL:   tmpl(sn.IconURL),

pkg/services/ngalert/notifier/channels/slack_test.go

@@ -64,6 +64,7 @@ func TestSlackNotifier(t *testing.T) {
 			},
 			expMsg: &slackMessage{
 				Channel:   "#testchannel",
+				Text:      "[FIRING:1]  (val1)",
 				Username:  "Grafana",
 				IconEmoji: ":emoji:",
 				Attachments: []attachment{
@@ -99,6 +100,7 @@ func TestSlackNotifier(t *testing.T) {
 			},
 			expMsg: &slackMessage{
 				Channel:   "#testchannel",
+				Text:      "[FIRING:1]  (val1)",
 				Username:  "Grafana",
 				IconEmoji: ":emoji:",
 				Attachments: []attachment{
@@ -134,6 +136,7 @@ func TestSlackNotifier(t *testing.T) {
 			},
 			expMsg: &slackMessage{
 				Channel:   "#testchannel",
+				Text:      "[FIRING:1]  (val1)",
 				Username:  "Grafana",
 				IconEmoji: ":emoji:",
 				Attachments: []attachment{
@@ -177,6 +180,7 @@ func TestSlackNotifier(t *testing.T) {
 			},
 			expMsg: &slackMessage{
 				Channel:   "#testchannel",
+				Text:      "2 firing, 0 resolved",
 				Username:  "Grafana",
 				IconEmoji: ":emoji:",
 				Attachments: []attachment{
@@ -225,6 +229,7 @@ func TestSlackNotifier(t *testing.T) {
 			},
 			expMsg: &slackMessage{
 				Channel:   "#testchannel",
+				Text:      "[FIRING:1]  (val1)",
 				Username:  "Grafana",
 				IconEmoji: ":emoji:",
 				Attachments: []attachment{

pkg/tests/api/alerting/api_notification_channel_test.go

@@ -2099,6 +2099,7 @@ var expNonEmailNotifications = map[string][]string{
 	"slack_recv1/slack_test_without_token": {
 		`{
 		  "channel": "#test-channel",
+          "text": "Integration Test [FIRING:1] SlackAlert1 (default)",
 		  "username": "Integration Test",
 		  "icon_emoji": "🚀",
 		  "icon_url": "https://awesomeemoji.com/rocket",
@@ -2128,6 +2129,7 @@ var expNonEmailNotifications = map[string][]string{
 	"slack_recvX/slack_testX": {
 		`{
 		  "channel": "#test-channel",
+          "text": "[FIRING:1] SlackAlert2 (default)",
 		  "username": "Integration Test",
 		  "attachments": [
 			{