fix(database): db migration improvements EE-2688 (#6662)

api/database/boltdb/export.go

@@ -8,9 +8,30 @@ import (
 	bolt "go.etcd.io/bbolt"
 )
 
+func backupMetadata(connection *bolt.DB) (map[string]interface{}, error) {
+	buckets := map[string]interface{}{}
+
+	err := connection.View(func(tx *bolt.Tx) error {
+		err := tx.ForEach(func(name []byte, bucket *bolt.Bucket) error {
+			bucketName := string(name)
+			bucket = tx.Bucket([]byte(bucketName))
+			seqId := bucket.Sequence()
+			buckets[bucketName] = int(seqId)
+			return nil
+		})
+
+		return err
+	})
+
+	return buckets, err
+}
+
+// ExportJSON creates a JSON representation from a DbConnection. You can include
+// the database's metadata or ignore it. Ensure the database is closed before
+// using this function
 // inspired by github.com/konoui/boltdb-exporter (which has no license)
 // but very much simplified, based on how we use boltdb
-func (c *DbConnection) exportJson(databasePath string) ([]byte, error) {
+func (c *DbConnection) ExportJson(databasePath string, metadata bool) ([]byte, error) {
 	logrus.WithField("databasePath", databasePath).Infof("exportJson")
 
 	connection, err := bolt.Open(databasePath, 0600, &bolt.Options{Timeout: 1 * time.Second, ReadOnly: true})
@@ -20,6 +41,13 @@ func (c *DbConnection) exportJson(databasePath string) ([]byte, error) {
 	defer connection.Close()
 
 	backup := make(map[string]interface{})
+	if metadata {
+		meta, err := backupMetadata(connection)
+		if err != nil {
+			logrus.WithError(err).Errorf("Failed exporting metadata: %v", err)
+		}
+		backup["__metadata"] = meta
+	}
 
 	err = connection.View(func(tx *bolt.Tx) error {
 		err = tx.ForEach(func(name []byte, bucket *bolt.Bucket) error {
@@ -45,15 +73,20 @@ func (c *DbConnection) exportJson(databasePath string) ([]byte, error) {
 			}
 			if bucketName == "version" {
 				backup[bucketName] = version
+				return nil
 			}
 			if len(list) > 0 {
 				if bucketName == "ssl" ||
 					bucketName == "settings" ||
 					bucketName == "tunnel_server" {
-					backup[bucketName] = list[0]
+					backup[bucketName] = nil
+					if len(list) > 0 {
+						backup[bucketName] = list[0]
+					}
 					return nil
 				}
 				backup[bucketName] = list
+				return nil
 			}
 
 			return nil