Config syntax parsing and signature_version in S3

[galactose]

Discovered I had a syntactically incorrect ~/.aws/config INI file, the following snippet was in it.

[default]
output = json
region = ap-southeast-2
s3 = signature_version = s3v4

When attempting to get a client to S3 I got the following traceback:

  File "s3_sse_key_compromise.py", line 37, in handler
    print session.client('s3')
  File "/usr/local/lib/python2.7/site-packages/boto3/session.py", line 263, in client
    aws_session_token=aws_session_token, config=config)
  File "/usr/local/lib/python2.7/site-packages/botocore/session.py", line 836, in create_client
    client_config=config, api_version=api_version)
  File "/usr/local/lib/python2.7/site-packages/botocore/client.py", line 70, in create_client
    verify, credentials, scoped_config, client_config, endpoint_bridge)
  File "/usr/local/lib/python2.7/site-packages/botocore/client.py", line 224, in _get_client_args
    verify, credentials, scoped_config, client_config, endpoint_bridge)
  File "/usr/local/lib/python2.7/site-packages/botocore/args.py", line 45, in get_client_args
    endpoint_url, is_secure, scoped_config)
  File "/usr/local/lib/python2.7/site-packages/botocore/args.py", line 103, in compute_client_args
    service_name, region_name, endpoint_url, is_secure)
  File "/usr/local/lib/python2.7/site-packages/botocore/client.py", line 300, in resolve
    resolved, service_name, region_name, endpoint_url, is_secure)
  File "/usr/local/lib/python2.7/site-packages/botocore/client.py", line 317, in _create_endpoint
    if self._is_s3_dualstack_mode(service_name):
  File "/usr/local/lib/python2.7/site-packages/botocore/client.py", line 351, in _is_s3_dualstack_mode
    enabled = self.scoped_config.get('s3', {}).get(
AttributeError: 'str' object has no attribute 'get'

When I finally realised that the syntax of my INI was incorrect I fixed it in the following manner

[default]
output = json
region = ap-southeast-2
s3 =
    signature_version = s3v4

This fixed my error, is s3 = signature_version = s3v4 considered syntactically incorrect? If so should the config syntax issue be caught before it gets to the point where the s3 key is queried for a dictionary and fails when it gets a string? This took a bit of time to work out where the source of my problems were and it would be good to get a clearer error message.

[dstufft]

Yea, that's because the INI format isn't particularly expressive, so we've had to layer on additional conventions to deal with more complex data types. I do think that it would be a great feature to validate the configuration though, so I'm going to mark this as a feature request for that.

[stobrien89]

This still appears to be an issue.

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