Docserver overhaul: Gitiles away from me.

chrome/common/extensions/docs/server2/environment_wrappers.py

+# Copyright 2013 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.
+
+import json
+import logging
+import os
+
+from environment import IsAppEngine, IsComputeEngine, IsTest
+
+
+_METADATA_SERVER = 'http://metadata/computeMetadata/v1/instance/service-accounts'
+_SERVICE_ACCOUNT = 'default'
+
+# The environment variable to use as a fallback token source.
+_ACCESS_TOKEN_ENV = 'DOCSERVER_ACCESS_TOKEN'
+
+
+def CreateUrlFetcher(base_path=None):
+  if IsAppEngine():
+    from url_fetcher_appengine import UrlFetcherAppengine
+    fetcher = UrlFetcherAppengine()
+  elif not IsTest():
+    from url_fetcher_urllib2 import UrlFetcherUrllib2
+    fetcher = UrlFetcherUrllib2()
+  else:
+    from url_fetcher_fake import UrlFetcherFake
+    fetcher = UrlFetcherFake()
+  fetcher.SetBasePath(base_path)
+  return fetcher
+
+
+def CreatePersistentObjectStore(namespace):
+  if IsAppEngine():
+    from persistent_object_store_appengine import PersistentObjectStoreAppengine
+    object_store = PersistentObjectStoreAppengine(namespace)
+  else:
+    from persistent_object_store_fake import PersistentObjectStoreFake
+    object_store = PersistentObjectStoreFake(namespace)
+  return object_store
+
+
+def GetAccessToken():
+  '''Acquires an access token either from the metadata service (if running on
+  a real CE VM) or the DOCSERVER_ACCESS_TOKEN environment variable.
+
+  This may return None if no token is available. That should never happen while
+  running on a VM.
+  '''
+  # Attempt to grab an access token from the VM instance's metadata.
+  if IsComputeEngine():
+    fetcher = CreateUrlFetcher()
+    token_uri = '%s/%s/token' % (_METADATA_SERVER, _SERVICE_ACCOUNT)
+    token_response = None
+    try:
+      token_response = fetcher.Fetch(token_uri,
+          headers={'Metadata-Flavor': 'Google'})
+      if token_response.status_code == 200:
+        return json.loads(token_response.content)['access_token']
+    except Exception as e:
+      logging.warn('Failed to fetch access token from VM metadata.')
+      pass
+
+  logging.warn('Using access token from local environment.')
+  access_token = os.getenv(_ACCESS_TOKEN_ENV)
+  if access_token is None:
+    logging.error('No access token available. '
+                  'Please set %s if you want things to work.' %
+                  _ACCESS_TOKEN_ENV)
+  return access_token