code: func (m *Mercury) AddPod(ctx context.Context, name, favor, desc string) (*types.Pod, error) {
  	key := fmt.Sprintf(podInfoKey, name)
  	favor = strings.ToUpper(favor)
  	if favor == "" {
  		favor = scheduler.MemoryPrior
  	} else if favor != scheduler.MemoryPrior && favor != scheduler.CPUPrior {
  		return nil, types.NewDetailedErr(types.ErrBadFaver,
  			fmt.Sprintf("got bad faver: %s", favor))
  	}
  	pod := &types.Pod{Name: name, Desc: desc, Favor: favor}
  
  	bytes, err := json.Marshal(pod)
  	if err != nil {
  		return nil, err
  	}
  	_, err = m.Put(ctx, key, string(bytes))
  	return pod, err
  }
docs: // AddPod add a pod
  // save it to etcd
  // storage path in etcd is `/pod/info/:podname`