code: func WriteFileToPackage(localpath string, packagepath string, tw *tar.Writer) error {
  	vmLogger.Debug("Writing file to tarball:", packagepath)
  	fd, err := os.Open(localpath)
  	if err != nil {
  		return fmt.Errorf("%s: %s", localpath, err)
  	}
  	defer fd.Close()
  
  	is := bufio.NewReader(fd)
  	return WriteStreamToPackage(is, localpath, packagepath, tw)
  
  }
docs: //WriteFileToPackage writes a file to the tarball