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

   1 # Copyright 2013 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 import json
   6 import logging
   7 import os
   8
   9 from environment import IsAppEngine, IsComputeEngine, IsTest
  10
  11
  12 _METADATA_SERVER = 'http://metadata/computeMetadata/v1/instance/service-accounts'
  13 _SERVICE_ACCOUNT = 'default'
  14
  15 # The environment variable to use as a fallback token source.
  16 _ACCESS_TOKEN_ENV = 'DOCSERVER_ACCESS_TOKEN'
  17
  18
  19 def CreateUrlFetcher(base_path=None):
  20   if IsAppEngine():
  21     from url_fetcher_appengine import UrlFetcherAppengine
  22     fetcher = UrlFetcherAppengine()
  23   elif not IsTest():
  24     from url_fetcher_urllib2 import UrlFetcherUrllib2
  25     fetcher = UrlFetcherUrllib2()
  26   else:
  27     from url_fetcher_fake import UrlFetcherFake
  28     fetcher = UrlFetcherFake()
  29   fetcher.SetBasePath(base_path)
  30   return fetcher
  31
  32
  33 def CreatePersistentObjectStore(namespace):
  34   if IsAppEngine():
  35     from persistent_object_store_appengine import PersistentObjectStoreAppengine
  36     object_store = PersistentObjectStoreAppengine(namespace)
  37   else:
  38     from persistent_object_store_fake import PersistentObjectStoreFake
  39     object_store = PersistentObjectStoreFake(namespace)
  40   return object_store
  41
  42
  43 def GetAccessToken():
  44   '''Acquires an access token either from the metadata service (if running on
  45   a real CE VM) or the DOCSERVER_ACCESS_TOKEN environment variable.
  46
  47   This may return None if no token is available. That should never happen while
  48   running on a VM.
  49   '''
  50   # Attempt to grab an access token from the VM instance's metadata.
  51   if IsComputeEngine():
  52     fetcher = CreateUrlFetcher()
  53     token_uri = '%s/%s/token' % (_METADATA_SERVER, _SERVICE_ACCOUNT)
  54     token_response = None
  55     try:
  56       token_response = fetcher.Fetch(token_uri,
  57           headers={'Metadata-Flavor': 'Google'})
  58       if token_response.status_code == 200:
  59         return json.loads(token_response.content)['access_token']
  60     except Exception as e:
  61       logging.warn('Failed to fetch access token from VM metadata.')
  62       pass
  63
  64   logging.warn('Using access token from local environment.')
  65   access_token = os.getenv(_ACCESS_TOKEN_ENV)
  66   if access_token is None:
  67     logging.error('No access token available. '
  68                   'Please set %s if you want things to work.' %
  69                   _ACCESS_TOKEN_ENV)
  70   return access_token