promote: return early if migration job already completed

Co-authored-by: Morten Lied Johansen <[email protected]>

Author: tronghn

internal/pkg/promote/promote.go

@@ -4,13 +4,13 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"github.com/nais/cloudsql-migrator/internal/pkg/migration"
 	"time"
 
 	monitoring "cloud.google.com/go/monitoring/apiv3/v2"
 	"cloud.google.com/go/monitoring/apiv3/v2/monitoringpb"
 	"github.com/nais/cloudsql-migrator/internal/pkg/common_main"
 	"github.com/nais/cloudsql-migrator/internal/pkg/instance"
+	"github.com/nais/cloudsql-migrator/internal/pkg/migration"
 	"github.com/nais/cloudsql-migrator/internal/pkg/resolved"
 	"google.golang.org/api/datamigration/v1"
 	"google.golang.org/api/iterator"
@@ -29,6 +29,11 @@ func CheckReadyForPromotion(ctx context.Context, source, target *resolved.Instan
 		return err
 	}
 
+	if migrationJob.State == "COMPLETED" {
+		mgr.Logger.Info("migration job is already completed, continuing...", "migrationName", migrationName)
+		return nil
+	}
+
 	if migrationJob.State != "RUNNING" {
 		return fmt.Errorf("migration job is not running: %s", migrationJob.State)
 	}