Add a timeout for GCE detection.

oauth2client/client.py

@@ -26,6 +26,7 @@
 import json
 import logging
 import os
+import socket
 import sys
 import time
 import six
@@ -930,12 +931,22 @@ def _detect_gce_environment(urlopen=None):
  Compute Engine.
  """
  urlopen = urlopen or urllib.request.urlopen
-
+ # Note: the explicit `timeout` below is a workaround. The underlying
+ # issue is that resolving an unknown host on some networks will take
+ # 20-30 seconds; making this timeout short fixes the issue, but
+ # could lead to false negatives in the event that we are on GCE, but
+ # the metadata resolution was particularly slow. The latter case is
+ # "unlikely".
  try:
- response = urlopen('http://metadata.google.internal')
+ response = urlopen('http://metadata.google.internal/', timeout=1)
  return any('Metadata-Flavor: Google' in header
  for header in response.info().headers)
- except urllib.error.URLError:
+ except socket.timeout:
+ logger.info('Timeout attempting to reach GCE metadata service.')
+ return False
+ except urllib.error.URLError as e:
+ if isinstance(getattr(e, 'reason', None), socket.timeout):
+ logger.info('Timeout attempting to reach GCE metadata service.')
  return False
 
 

tests/test_oauth2client.py

@@ -25,13 +25,11 @@
 import base64
 import datetime
 import json
-try:
- from mox3 import mox
-except ImportError:
- import mox
 import os
 import time
 import unittest
+
+import mock
 import six
 from six.moves import urllib
 
@@ -208,37 +206,19 @@ def test_get_environment_gae_local(self):
 
  def test_get_environment_gce_production(self):
  os.environ['SERVER_SOFTWARE'] = ''
- mockResponse = MockResponse(['Metadata-Flavor: Google\r\n'])
-
- m = mox.Mox()
-
- urllib2_urlopen = m.CreateMock(object)
- urllib2_urlopen.__call__(('http://metadata.google.internal'
- )).AndReturn(mockResponse)
-
- m.ReplayAll()
-
- self.assertEqual('GCE_PRODUCTION', _get_environment(urllib2_urlopen))
-
- m.UnsetStubs()
- m.VerifyAll()
+ with mock.patch.object(urllib.request, 'urlopen') as urlopen:
+ urlopen.return_value = MockResponse(['Metadata-Flavor: Google\r\n'])
+ self.assertEqual('GCE_PRODUCTION', _get_environment())
+ urlopen.assert_called_once_with(
+ 'http://metadata.google.internal/', timeout=1)
 
  def test_get_environment_unknown(self):
  os.environ['SERVER_SOFTWARE'] = ''
- mockResponse = MockResponse([])
-
- m = mox.Mox()
-
- urllib2_urlopen = m.CreateMock(object)
- urllib2_urlopen.__call__(('http://metadata.google.internal'
- )).AndReturn(mockResponse)
-
- m.ReplayAll()
-
- self.assertEqual(DEFAULT_ENV_NAME, _get_environment(urllib2_urlopen))
-
- m.UnsetStubs()
- m.VerifyAll()
+ with mock.patch.object(urllib.request, 'urlopen') as urlopen:
+ urlopen.return_value = MockResponse([])
+ self.assertEqual(DEFAULT_ENV_NAME, _get_environment())
+ urlopen.assert_called_once_with(
+ 'http://metadata.google.internal/', timeout=1)
 
  def test_get_environment_variable_file(self):
  environment_variable_file = datafile(

tox.ini

@@ -4,14 +4,15 @@ envlist = py26,py27,py33,py34,pypy,cover
 [testenv]
 basedeps = keyring
  mox3
+ mock
  pycrypto==2.6
  django>=1.5,<1.6
  webtest
  nose
 deps = {[testenv]basedeps}
  pyopenssl==0.14
 setenv = PYTHONPATH=../google_appengine
-commands = nosetests --ignore-files=test_appengine\.py
+commands = nosetests --ignore-files=test_appengine\.py {posargs}
 
 # whitelist
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