code: func (m *Mercury) UpdateProcessing(ctx context.Context, opts *types.DeployOptions, nodename string, count int) error {
  	processingKey := filepath.Join(containerProcessingPrefix, opts.Name, opts.Entrypoint.Name, nodename, opts.ProcessIdent)
  	_, err := m.Update(ctx, processingKey, fmt.Sprintf("%d", count))
  	return err
  }
docs: // UpdateProcessing update processing status in etcd