code: func Labels(executor, snapshotter string) map[string]string {
  	hostname, err := os.Hostname()
  	if err != nil {
  		hostname = "unknown"
  	}
  	labels := map[string]string{
  		worker.LabelExecutor:    executor,
  		worker.LabelSnapshotter: snapshotter,
  		worker.LabelHostname:    hostname,
  	}
  	return labels
  }
docs: // Labels returns default labels
  // utility function. could be moved to the constructor logic?