code: func (r *RemoteRuntimeService) Attach(req *runtimeapi.AttachRequest) (*runtimeapi.AttachResponse, error) {
  	ctx, cancel := getContextWithTimeout(r.timeout)
  	defer cancel()
  
  	resp, err := r.runtimeClient.Attach(ctx, req)
  	if err != nil {
  		klog.Errorf("Attach %s from runtime service failed: %v", req.ContainerId, err)
  		return nil, err
  	}
  
  	if resp.Url == "" {
  		errorMessage := "URL is not set"
  		klog.Errorf("Exec failed: %s", errorMessage)
  		return nil, errors.New(errorMessage)
  	}
  	return resp, nil
  }
docs: // Attach prepares a streaming endpoint to attach to a running container, and returns the address.