Update the diffs worker to not fail if the repository is removed before diffs are computed.

data/model.py

@@ -662,7 +662,9 @@ def get_image_by_id(namespace_name, repository_name, docker_image_id):
                               Image.docker_image_id == docker_image_id))
 
   if not fetched:
-    raise DataModelException('Unable to find image for tag with repo.')
+    raise DataModelException('Unable to find image \'%s\' for repo \'%s/%s\'' %
+                             (docker_image_id, namespace_name,
+                              repository_name))
 
   return fetched[0]
 

workers/diffsworker.py

@@ -8,6 +8,7 @@ from apscheduler.scheduler import Scheduler
 
 from data.queue import image_diff_queue
 from data.database import db as db_connection
+from data.model import DataModelException
 from endpoints.registry import process_image_changes
 
 
@@ -29,8 +30,18 @@ def process_work_items():
     logger.debug('Queue gave us some work: %s' % item.body)
 
     request = json.loads(item.body)
-    process_image_changes(request['namespace'], request['repository'],
-                          request['image_id'])
+    try:
+      image_id = request['image_id']
+      namespace = request['namespace']
+      repository = request['repository']
+
+      process_image_changes(namespace, repository, image_id)
+    except DataModelException:
+      # This exception is unrecoverable, and the item should continue and be
+      # marked as complete.
+      msg = ('Image does not exist in database \'%s\' for repo \'%s/\'%s\'' %
+             (image_id, namespace, repository))
+      logger.warning(msg)
 
     image_diff_queue.complete(item)