code: func (daemon *Daemon) reloadRegistryMirrors(conf *config.Config, attributes map[string]string) error {
  	// update corresponding configuration
  	if conf.IsValueSet("registry-mirrors") {
  		daemon.configStore.Mirrors = conf.Mirrors
  		if err := daemon.RegistryService.LoadMirrors(conf.Mirrors); err != nil {
  			return err
  		}
  	}
  
  	// prepare reload event attributes with updatable configurations
  	if daemon.configStore.Mirrors != nil {
  		mirrors, err := json.Marshal(daemon.configStore.Mirrors)
  		if err != nil {
  			return err
  		}
  		attributes["registry-mirrors"] = string(mirrors)
  	} else {
  		attributes["registry-mirrors"] = "[]"
  	}
  
  	return nil
  }
docs: // reloadRegistryMirrors updates configuration with registry mirror options
  // and updates the passed attributes