swarmbucket: add $project template parameter

appengine/cr-buildbucket/config.py

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Access to bucket configurations.
 
 Stores bucket list in datastore, synchronizes it with bucket configs in
 project repositories: `projects/<project_id>:<buildbucket-app-id>.cfg`.
 """
 
@@ skipping 122 matching lines @@
 @ndb.tasklet
 def get_buckets_async():
   """Returns a list of project_config_pb2.Bucket objects."""
   buckets = yield Bucket.query().fetch_async()
   raise ndb.Return([parse_bucket_config(b.config_content) for b in buckets])
 
 
 @ndb.non_transactional
 @ndb.tasklet
 def get_bucket_async(name):
-  """Returns a project_config_pb2.Bucket by name."""
+  """Returns a (project, project_config_pb2.Bucket) tuple."""
   bucket = yield Bucket.get_by_id_async(name)
   if bucket is None:
-    raise ndb.Return(None)
-  raise ndb.Return(parse_bucket_config(bucket.config_content))
+    raise ndb.Return(None, None)
+  raise ndb.Return(
+      bucket.project_id, parse_bucket_config(bucket.config_content))
 
 
 def cron_update_buckets():
   """Synchronizes Bucket entities with configs fetched from luci-config."""
   config_map = config.get_project_configs(
     cfg_path(), project_config_pb2.BuildbucketCfg)
 
   buckets_of_project = {
     pid: set(b.name for b in pcfg.buckets)
     for pid, (_, pcfg) in config_map.iteritems()
@@ skipping 64 matching lines @@
   config_url = config.get_config_set_location('projects/%s' % project_id)
   if config_url is None:  # pragma: no cover
     return None
   try:
     loc = gitiles.Location.parse(config_url)
   except ValueError:  # pragma: no cover
     logging.exception(
         'Not a valid Gitiles URL %r of project %s', config_url, project_id)
     return None
   return str(loc.join(cfg_path()))