Connexion hides real errors in endpoint handling module

[tommyjcarpenter]

Description

If you have an error in the module that handles an endpoint, Connexion bombs while importing the API, so you never see what the real error is. You have to drop into python and import the endpoint-handling module to see the real error. This makes debugging somewhat painful.

Expected bahaviour

If I drop into python, I see the real error in my module (in this case, a missing import):

Python 3.5.0 (default, Sep 23 2015, 04:41:38)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.72)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from query_service.controllers import controller
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/tommy/Development/query_service/py/query_service/controllers/controller.py", line 1, in <module>
    import psycopg2
ImportError: No module named 'psycopg2'

Actual behaviour

Failed to add operation for GET /tenant/{vmname}
Traceback (most recent call last):
  File "py/query_service/rest_service.py", line 7, in <module>
    app.add_api('swagger.yaml', arguments={'title': 'Query Service'})
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/app.py", line 146, in add_api
    debug=self.debug)
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/api.py", line 132, in __init__
    self.add_paths()
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/api.py", line 203, in add_paths
    six.reraise(*sys.exc_info())
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/six.py", line 686, in reraise
    raise value
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/api.py", line 192, in add_paths
    self.add_operation(method, path, endpoint, path_parameters)
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/api.py", line 165, in add_operation
    resolver=self.resolver)
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/operation.py", line 172, in __init__
    resolution = resolver.resolve(self)
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/resolver.py", line 51, in resolve
    return Resolution(self.resolve_function_from_operation_id(operation_id), operation_id)
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/resolver.py", line 72, in resolve_function_from_operation_id
    return self.function_resolver(operation_id)
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/utils.py", line 109, in get_function_from_name
    function = deep_getattr(module, attr_path)
  File "/Users/tommy/.virtualenvs/aai/lib/python3.5/site-packages/connexion/utils.py", line 91, in deep_getattr
    return functools.reduce(getattr, attr.split('.'), obj)
AttributeError: module 'controllers' has no attribute 'controller'

Steps to reproduce

Have an import error in the module that handles an endpoint. In this case my swagger.yaml had the line: operationId: "controllers.controller.tenant_vmname_get", but " controllers.controller had an import error.

Additional info:

Output of the commands:

• python --version

Python 3.5.0

• pip show connexion | grep "^Version\:"

Version: 1.0.91

[KarimJedda]

I second this one, happened so many times to me and didn't understand why.

[hjacobs]

I guess we have to change this function and optionally (if "debug" is set?) print all ImportErrors:
https://github.com/zalando/connexion/blob/master/connexion/utils.py#L94