rdb: add support for wait on backup resource

api/rdb/v1/rdb_utils.go

@@ -61,3 +61,50 @@ func (s *API) WaitForInstance(req *WaitForInstanceRequest) (*Instance, error) {
 	}
 	return instance.(*Instance), nil
 }
+
+type WaitForDatabaseBackupRequest struct {
+	DatabaseBackupID string
+	Region           scw.Region
+	Timeout          *time.Duration
+	RetryInterval    *time.Duration
+}
+
+// WaitForDatabaseBackup waits for the backup to be in a "terminal state" before returning.
+// This function can be used to wait for a backup to be ready for example.
+func (s *API) WaitForDatabaseBackup(req *WaitForDatabaseBackupRequest) (*DatabaseBackup, error) {
+	timeout := defaultTimeout
+	if req.Timeout != nil {
+		timeout = *req.Timeout
+	}
+	retryInterval := defaultRetryInterval
+	if req.RetryInterval != nil {
+		retryInterval = *req.RetryInterval
+	}
+
+	terminalStatus := map[DatabaseBackupStatus]struct{}{
+		DatabaseBackupStatusReady: {},
+		DatabaseBackupStatusError: {},
+	}
+
+	backup, err := async.WaitSync(&async.WaitSyncConfig{
+		Get: func() (interface{}, bool, error) {
+			res, err := s.GetDatabaseBackup(&GetDatabaseBackupRequest{
+				DatabaseBackupID: req.DatabaseBackupID,
+				Region:           req.Region,
+			})
+
+			if err != nil {
+				return nil, false, err
+			}
+			_, isTerminal := terminalStatus[res.Status]
+
+			return res, isTerminal, nil
+		},
+		Timeout:          timeout,
+		IntervalStrategy: async.LinearIntervalStrategy(retryInterval),
+	})
+	if err != nil {
+		return nil, errors.Wrap(err, "waiting for database backup failed")
+	}
+	return backup.(*DatabaseBackup), nil
+}