Using storage to create layers and image

[fanux]

options, err := storage.DefaultStoreOptions(unshare.IsRootless(), unshare.GetRootlessUID())
store, err := storage.GetStore(options)

_, err = store.CreateLayer("foo", "", nil, "", true, nil)

b := bytes.NewBuffer([]byte("hello"))
store.SetLayerBigData("foo", "key", b)

Then you will got the layer:

cat /var/lib/containers/storage/overlay-layers/foo/key 
hello

[fanux]

func wrongManifestDigest(b []byte) (digest.Digest, error) {
	return digest.Canonical.FromBytes(b), nil
}

var manifest = `{
  "schemaVersion": 2,
  "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
  "config": {
    "mediaType": "application/vnd.docker.container.image.v1+json",
    "size": 1457,
    "digest": "sha256:24d4f50961544fdb669075c442509f194bdc4c0e344bde06e35dbd55af842a32"
  },
  "layers": []
}`

	imageOptions := &storage.ImageOptions{
		Digest: digest.Digest("sha256:24d4f50961544fdb669075c442509f194bdc4c0e344bde06e35dbd55af842a32"),
	}


	im, err := store.CreateImage("docker.io/fanux/merge6", nil, "foo", `{"signatures-sizes":{"sha256:24d4f50961544fdb669075c442509f194bdc4c0e344bde06e35dbd55af842a32":[]}}`, imageOptions)

	store.SetImageBigData("docker.io/fanux/merge6", "manifest", []byte(manifest), wrongManifestDigest)

Set image BigData:

    ├── overlay-images
    │   ├── docker.io
    │   │   └── fanux
    │   │       └── merge6
    │   │           └── =aW1hZ2VLZXk=

[root@iZ2ze4vo1tjx7vf1b0ab2tZ sealer]# cat /var/lib/containers/storage/overlay-images/docker.io/fanux/merge6/\=aW1hZ2VLZXk\= 
{
  "schemaVersion": 2,
  "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
  "config": {
    "mediaType": "application/vnd.docker.container.image.v1+json",
    "size": 1457,
    "digest": "sha256:24d4f50961544fdb669075c442509f194bdc4c0e344bde06e35dbd55af842a32"
  },
  "layers": []
}