def image_bundle
    @image_bundle ||=
      Hoosegow::ImageBundle.new.tap do |image|
        image.add(File.expand_path('../../*', __FILE__), :ignore_hidden => true)
        image.add(File.join(@inmate_dir, "*"), :prefix => 'inmate')
        image.ruby_version = @ruby_version
      end
  end
Public: The thing that defines which files go into the docker image tarball.