Adds a no-op migration for metadata v3

Signed-off-by: John Howard <jhoward@microsoft.com>

metadata/db.go

@@ -43,7 +43,7 @@ const (
 	// dbVersion represents updates to the schema
 	// version which are additions and compatible with
 	// prior version of the same schema.
-	dbVersion = 2
+	dbVersion = 3
 )
 
 // DB represents a metadata database backed by a bolt

metadata/db_test.go

@@ -265,6 +265,16 @@ func TestMigrations(t *testing.T) {
 				return nil
 			},
 		},
+
+		{
+			name: "NoOp",
+			init: func(tx *bolt.Tx) error {
+				return nil
+			},
+			check: func(tx *bolt.Tx) error {
+				return nil
+			},
+		},
 	}
 
 	if len(migrationTests) != len(migrations) {

metadata/migrations.go

@@ -45,6 +45,11 @@ var migrations = []migration{
 		version: 2,
 		migrate: migrateIngests,
 	},
+	{
+		schema:  "v1",
+		version: 3,
+		migrate: noOpMigration,
+	},
 }
 
 // addChildLinks Adds children key to the snapshotters to enforce snapshot
@@ -154,3 +159,10 @@ func migrateIngests(tx *bolt.Tx) error {
 
 	return nil
 }
+
+// noOpMigration was for a database change from boltdb/bolt which is no
+// longer being supported, to go.etcd.io/bbolt which is the currently
+// maintained repo for boltdb.
+func noOpMigration(tx *bolt.Tx) error {
+	return nil
+}