code: func (ds *dockerService) Attach(_ context.Context, req *runtimeapi.AttachRequest) (*runtimeapi.AttachResponse, error) {
  	if ds.streamingServer == nil {
  		return nil, streaming.NewErrorStreamingDisabled("attach")
  	}
  	_, err := checkContainerStatus(ds.client, req.ContainerId)
  	if err != nil {
  		return nil, err
  	}
  	return ds.streamingServer.GetAttach(req)
  }
docs: // Attach prepares a streaming endpoint to attach to a running container, and returns the address.