code: func (svc *Service) logSink(f *os.File, r io.ReadCloser) {
  	_, err := io.Copy(f, r)
  	if err != nil {
  		log.Warningf("Service %s - log sink failed: %v", svc.name, err)
  	}
  	f.Close()
  	r.Close()
  }
docs: // logSink copies output from the given reader to a log file, before closing
  // both the reader and the log file.