Alerting: Ignore obsolete notification channels referenced by alerts (#25302)

* Ignore obsolete notification channel

* Fix tests

* Update pkg/services/alerting/rule.go
Co-authored-by: Marcus Efraimsson <marcus.efraimsson@gmail.com>

pkg/services/alerting/rule.go

@@ -140,9 +140,10 @@ func NewRuleFromDBAlert(ruleDef *models.Alert) (*Rule, error) {
 		if id, err := jsonModel.Get("id").Int64(); err == nil {
 			uid, err := translateNotificationIDToUID(id, ruleDef.OrgId)
 			if err != nil {
-				return nil, ValidationError{Reason: "Unable to translate notification id to uid, " + err.Error(), DashboardID: model.DashboardID, AlertID: model.ID, PanelID: model.PanelID}
-			}
+				logger.Error("Unable to translate notification id to uid", "error", err.Error(), "dashboardId", model.DashboardID, "alertId", model.ID, "panelId", model.PanelID, "notificationId", id)
+			} else {
 				model.Notifications = append(model.Notifications, uid)
+			}
 		} else if uid, err := jsonModel.Get("uid").String(); err == nil {
 			model.Notifications = append(model.Notifications, uid)
 		} else {

pkg/services/alerting/rule_test.go

@@ -125,7 +125,8 @@ func TestAlertRuleModel(t *testing.T) {
 					"frequency": "60s",
 					"conditions": [{"type": "test", "prop": 123 }],
 					"notifications": [
-						{"id": 999}
+						{"id": 999},
+						{"uid": "notifier2"}
 					]
 				}
 				`
@@ -142,10 +143,11 @@ func TestAlertRuleModel(t *testing.T) {
 				Settings: alertJSON,
 			}
 
-			_, err := NewRuleFromDBAlert(alert)
-			Convey("raises an error", func() {
-				So(err, ShouldNotBeNil)
-				So(err.Error(), ShouldEqual, "Alert validation error: Unable to translate notification id to uid, Alert notification [ Id: 999, OrgId: 1 ] not found AlertId: 1 PanelId: 1 DashboardId: 1")
+			alertRule, err := NewRuleFromDBAlert(alert)
+			Convey("swallows the error", func() {
+				So(err, ShouldBeNil)
+				So(alertRule.Notifications, ShouldNotContain, "999")
+				So(alertRule.Notifications, ShouldContain, "notifier2")
 			})
 		})