code: func (s *Serf) SetTags(tags map[string]string) error {
  	// Check that the meta data length is okay
  	if len(s.encodeTags(tags)) > memberlist.MetaMaxSize {
  		return fmt.Errorf("Encoded length of tags exceeds limit of %d bytes",
  			memberlist.MetaMaxSize)
  	}
  
  	// Update the config
  	s.config.Tags = tags
  
  	// Trigger a memberlist update
  	return s.memberlist.UpdateNode(s.config.BroadcastTimeout)
  }
docs: // SetTags is used to dynamically update the tags associated with
  // the local node. This will propagate the change to the rest of
  // the cluster. Blocks until a the message is broadcast out.