NoCredentialsError if no credentials defined

[t-chaik]

Testing 1.3.7 and the fix for #1793:

boto                     2.49.0
boto3                    1.9.37
botocore                 1.12.37
moto                     1.3.7

Trying to run the context manager example:

Python 3.6.7 (default, Oct 21 2018, 08:08:16) 
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import boto3
>>> from moto import mock_s3
>>> with mock_s3():
...     conn = boto3.resource('s3', region_name='us-east-1')
...     conn.create_bucket(Bucket='mybucket')
... 

Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/boto3/resources/factory.py", line 520, in do_action
    response = action(self, *args, **kwargs)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/boto3/resources/action.py", line 83, in __call__
    response = getattr(parent.meta.client, operation_name)(**params)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/client.py", line 320, in _api_call
    return self._make_api_call(operation_name, kwargs)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/client.py", line 610, in _make_api_call
    operation_model, request_dict)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/endpoint.py", line 102, in make_request
    return self._send_request(request_dict, operation_model)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/endpoint.py", line 132, in _send_request
    request = self.create_request(request_dict, operation_model)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/endpoint.py", line 116, in create_request
    operation_name=operation_model.name)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/hooks.py", line 356, in emit
    return self._emitter.emit(aliased_event_name, **kwargs)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/hooks.py", line 228, in emit
    return self._emit(event_name, kwargs)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/hooks.py", line 211, in _emit
    response = handler(**kwargs)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/signers.py", line 90, in handler
    return self.sign(operation_name, request)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/signers.py", line 157, in sign
    auth.add_auth(request)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/auth.py", line 425, in add_auth
    super(S3SigV4Auth, self).add_auth(request)
  File "/home/martinblanchard/Work/env/buildgrid/lib/python3.6/site-packages/botocore/auth.py", line 357, in add_auth
    raise NoCredentialsError
botocore.exceptions.NoCredentialsError: Unable to locate credentials

Setting AWS_SECRET_ACCESS_KEY and AWS_ACCESS_KEY_ID (to whatever) seems to fix the issue. Not sure if mocking without providing any credential is something actually supported by moto, but it used to work with moto<1.3.7, boto3<1.8.0 and botocore<1.11.0.

[spulec]

Closed with #1952

[t-chaik]

@spulec: Thanks for the fix! Any idea when a new release will be cut? Would be nice to have that fix released in a stable version.

[yan12125]

Here's a concern that the fix added in #1952 breaks some other use cases: #2058