func registerImageLayer(cake *layercake.Docker, img *image.Image) { tmp, err := ioutil.TempDir("", "my-img") Expect(err).NotTo(HaveOccurred()) defer os.RemoveAll(tmp) Expect(ioutil.WriteFile(path.Join(tmp, img.ID), []byte("Hello"), 0700)).To(Succeed()) archiver, _ := archive.Tar(tmp, archive.Uncompressed) Expect(cake.Register(img, archiver)).To(Succeed()) }