Datastore / Pubsub emulators break when using default credentials

For clarity / brevity (edit by @dhermes). When using just the default credentials, the oauth2client refresh tries to generate an access token and append one to a datastore / pubsub request. However, this is not needed and can cause breakage.

There is a workaround in both datastore and pubsub. We should determine if this should be “fixed” with docs or with custom credential usage in the Connection constructors.

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Original report by @txomon : #1837 2nd issue

I think it is about mistakenly patching httplib for local testing.

Test script

from gcloud import datastore

client = datastore.Client()
entity = datastore.Entity(client.key('Test1'))
client.put(entity)

Setting up environment

This one needs:

• Application default credentials set up

Showcase

I think this manifests with a Connection refused error:

(ve) javier@theoden:~/projects/spinoffs/gae$ python test-script.py 
Traceback (most recent call last):
  File "test-script.py", line 5, in <module>
    client.put(entity)
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/gcloud/datastore/client.py", line 319, in put
    self.put_multi(entities=[entity])
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/gcloud/datastore/client.py", line 345, in put_multi
    current.commit()
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/gcloud/datastore/batch.py", line 260, in commit
    self._commit()
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/gcloud/datastore/batch.py", line 243, in _commit
    self.project, self._commit_request, self._id)
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/gcloud/datastore/connection.py", line 331, in commit
    _datastore_pb2.CommitResponse)
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/gcloud/datastore/connection.py", line 121, in _rpc
    data=request_pb.SerializeToString())
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/gcloud/datastore/connection.py", line 93, in _request
    method='POST', headers=headers, body=data)
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/oauth2client/client.py", line 631, in new_request
    redirections, connection_type)
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/httplib2/__init__.py", line 1314, in request
    (response, content) = self._request(conn, authority, uri, request_uri, method, body, headers, redirections, cachekey)
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/httplib2/__init__.py", line 1064, in _request
    (response, content) = self._conn_request(conn, request_uri, method, body, headers)
  File "/home/javier/projects/spinoffs/gae/ve/lib/python3.4/site-packages/httplib2/__init__.py", line 987, in _conn_request
    conn.connect()
  File "/usr/lib/python3.4/http/client.py", line 871, in connect
    self.timeout, self.source_address)
  File "/usr/lib/python3.4/socket.py", line 516, in create_connection
    raise err
  File "/usr/lib/python3.4/socket.py", line 507, in create_connection
    sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused

This is caused because it tries to make a auth token refresh against the emulator. There are no relevant logs for the emulator.

Workaround

I thought I had found a workaround but I cannot reproduce the workaround, therefore not a workaround.

The problem is the default credential, so it can be fixed by (ordered by personal preference):

1. Create a configuration with no default credentials, for the same project, or;
2. Remove the default credentials gcloud beta auth application-default revoke~

Hopefully you know how to patch the library not to collide!

[bendemaree]

Yes. I was assuming @txomon wanted that release for a specific release series vs. newer one and that’s the highest for 0.12.x. 🙂

[dhermes]

Gotcha. Thanks.