code: func (p *Pod) SaveRuntime() error {
  	path := filepath.Join(p.Root, RuntimeConfigPath)
  	buf, err := json.Marshal(p.RuntimePod)
  	if err != nil {
  		return err
  	}
  
  	return ioutil.WriteFile(path, buf, 0644)
  }
docs: // SaveRuntime persists just the runtime state. This should be called when the
  // pod is started.