Add support for pushing and pulling schema 2 manifests with remote layers

This is required for windows image support

data/model/oci/test/test_oci_manifest.py

@@ -239,3 +239,68 @@ def test_get_or_create_manifest_list(initialized_db):
 
   assert child_manifests[v1_manifest.digest].media_type.name == v1_manifest.media_type
   assert child_manifests[v2_manifest.digest].media_type.name == v2_manifest.media_type
+
+
+def test_get_or_create_manifest_with_remote_layers(initialized_db):
+  repository = create_repository('devtable', 'newrepo', None)
+
+  layer_json = json.dumps({
+    'config': {},
+    "rootfs": {
+      "type": "layers",
+      "diff_ids": []
+    },
+    "history": [
+      {
+        "created": "2018-04-03T18:37:09.284840891Z",
+        "created_by": "do something",
+      },
+      {
+        "created": "2018-04-03T18:37:09.284840891Z",
+        "created_by": "do something",
+      },
+    ],
+  })
+
+  # Add a blob containing the config.
+  _, config_digest = _populate_blob(layer_json)
+
+  # Add a blob of random data.
+  random_data = 'hello world'
+  _, random_digest = _populate_blob(random_data)
+
+  remote_digest = sha256_digest('something')
+
+  builder = DockerSchema2ManifestBuilder()
+  builder.set_config_digest(config_digest, len(layer_json))
+  builder.add_layer(remote_digest, 1234, urls=['http://hello/world'])
+  builder.add_layer(random_digest, len(random_data))
+  manifest = builder.build()
+
+  assert remote_digest in manifest.blob_digests
+  assert remote_digest not in manifest.local_blob_digests
+
+  assert manifest.has_remote_layer
+  assert manifest.leaf_layer_v1_image_id is None
+  assert manifest.get_v1_compatible_manifest('foo', 'bar', 'baz', None) is None
+
+  # Write the manifest.
+  created_tuple = get_or_create_manifest(repository, manifest, storage)
+  assert created_tuple is not None
+
+  created_manifest = created_tuple.manifest
+  assert created_manifest
+  assert created_manifest.media_type.name == manifest.media_type
+  assert created_manifest.digest == manifest.digest
+
+  # Verify the legacy image.
+  legacy_image = get_legacy_image_for_manifest(created_manifest)
+  assert legacy_image is None
+
+  # Verify the linked blobs.
+  blob_digests = {mb.blob.content_checksum for mb
+                  in ManifestBlob.select().where(ManifestBlob.manifest == created_manifest)}
+
+  assert random_digest in blob_digests
+  assert config_digest in blob_digests
+  assert remote_digest not in blob_digests