Modify routing labels to start with the same prefix __legacy

pkg/services/ngalert/migration/channel.go

@@ -141,9 +141,9 @@ func createRoute(channel *legacymodels.AlertNotification, receiverName string) (
 	//
 	// For example, if an alert needs to send to channel1 and channel2 it will have one label to route to the nested
 	// policy and two channel-specific labels to route to the correct contact points:
-	// - __use_legacy_channels__="true"
-	// - __contact_channel1__="true"
-	// - __contact_channel2__="true"
+	// - __legacy_use_channels__="true"
+	// - __legacy_c_channel1__="true"
+	// - __legacy_c_channel2__="true"
 	//
 	// If an alert needs to send to channel1 and the default channel, it will have one label to route to the nested
 	// policy and one channel-specific label to route to channel1, and a catch-all policy will ensure it also routes to
@@ -175,7 +175,7 @@ func createRoute(channel *legacymodels.AlertNotification, receiverName string) (
 
 // contactLabel creates a label matcher key used to route alerts to a contact point.
 func contactLabel(name string) string {
-	return fmt.Sprintf(ngmodels.MigratedContactLabelTemplate, name)
+	return ngmodels.MigratedContactLabelPrefix + name + "__"
 }
 
 var secureKeysToMigrate = map[string][]string{

pkg/services/ngalert/models/alert_rule.go

@@ -106,10 +106,12 @@ const (
 	// StateReasonAnnotation is the name of the annotation that explains the difference between evaluation state and alert state (i.e. changing state when NoData or Error).
 	StateReasonAnnotation = GrafanaReservedLabelPrefix + "state_reason"
 
+	// MigratedLabelPrefix is a label prefix for all labels created during legacy migration.
+	MigratedLabelPrefix = "__legacy_"
 	// MigratedUseLegacyChannelsLabel is created during legacy migration to route to separate nested policies for migrated channels.
-	MigratedUseLegacyChannelsLabel = "__use_legacy_channels__"
-	// MigratedContactLabelTemplate is created during legacy migration to route a migrated alert rule to a specific migrated channel.
-	MigratedContactLabelTemplate = "__contacts_%s__"
+	MigratedUseLegacyChannelsLabel = MigratedLabelPrefix + "use_channels__"
+	// MigratedContactLabelPrefix is created during legacy migration to route a migrated alert rule to a specific migrated channel.
+	MigratedContactLabelPrefix = MigratedLabelPrefix + "c_"
 	// MigratedAlertIdAnnotation is created during legacy migration to store the ID of the migrated legacy alert rule.
 	MigratedAlertIdAnnotation = "__alertId__"
 	// MigratedMessageAnnotation is created during legacy migration to store the migrated alert message.