Raise a 409 if we try to insert a tag twice at the same time

Also fixes handling of labels for existing manifests

Fixes #1775

endpoints/v2/manifest.py

@@ -20,13 +20,14 @@ from endpoints.common import parse_repository_name
 from endpoints.decorators import anon_protect
 from endpoints.v2 import v2_bp, require_repo_read, require_repo_write
 from endpoints.v2.errors import (BlobUnknown, ManifestInvalid, ManifestUnknown, TagInvalid,
-                                 NameInvalid)
+                                 NameInvalid, TagAlreadyExists)
 from endpoints.trackhelper import track_and_log
 from endpoints.notificationhelper import spawn_notification
 from util.registry.replication import queue_storage_replication
 from util.names import VALID_TAG_PATTERN
 from digest import digest_tools
 from data import model
+from data.model import TagAlreadyCreatedException
 from data.database import RepositoryTag
 
 logger = logging.getLogger(__name__)
@@ -451,9 +452,16 @@ def _write_manifest_itself(namespace_name, repo_name, manifest):
   # Store the manifest pointing to the tag.
   manifest_digest = manifest.digest
   leaf_layer_id = images_map[layers[-1].v1_metadata.docker_id].docker_image_id
-  tag_manifest, manifest_created = model.tag.store_tag_manifest(namespace_name, repo_name, tag_name,
-                                                                leaf_layer_id, manifest_digest,
-                                                                manifest.bytes)
+
+  try:
+    tag_manifest, manifest_created = model.tag.store_tag_manifest(namespace_name, repo_name,
+                                                                  tag_name, leaf_layer_id,
+                                                                  manifest_digest, manifest.bytes)
+  except TagAlreadyCreatedException:
+    logger.warning('Tag %s was already created under repository %s/%s pointing to image %s',
+                   tag_name, namespace_name, repo_name, leaf_layer_id)
+    raise TagAlreadyExists()
+
   if manifest_created:
     for key, value in layers[-1].v1_metadata.labels.iteritems():
       model.label.create_manifest_label(tag_manifest, key, value, 'manifest')