code: func (container *Container) BuildHostnameFile() error {
  	hostnamePath, err := container.GetRootResourcePath("hostname")
  	if err != nil {
  		return err
  	}
  	container.HostnamePath = hostnamePath
  	return ioutil.WriteFile(container.HostnamePath, []byte(container.Config.Hostname+"\n"), 0644)
  }
docs: // BuildHostnameFile writes the container's hostname file.