[TrivialFix] Fix BarbicanException error propagation

Fix BarbicanException error propagation in Deckhand by ensuring
that the exception details are passed around via str(e) rather
than e.message as the Barbican exceptions [0] don't have additional
attributes like falcon.

Example stack trace:

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/falcon/api.py", line 244, in __call__
    responder(req, resp, **params)
  File "./deckhand/policy.py", line 104, in handler
    return func(*args, **kwargs)
  File "./deckhand/control/buckets.py", line 70, in on_put
    self._prepare_secret_documents(documents)
  File "./deckhand/control/buckets.py", line 83, in _prepare_secret_documents
    secret_data = self.secrets_mgr.create(document)
  File "./deckhand/engine/secrets_manager.py", line 74, in create
    resp = self.barbican_driver.create_secret(**kwargs)
  File "./deckhand/barbican/driver.py", line 39, in create_secret
    LOG.exception(e.message)
AttributeError: 'HTTPServerError' object has no attribute 'message'

[0] https://github.com/openstack/python-barbicanclient/blob/master/barbicanclient/exceptions.py

Change-Id: I58410c3729fe4fd066227311589e5ee5d30dc171

deckhand/barbican/client_wrapper.py

@@ -61,9 +61,8 @@ class BarbicanClientWrapper(object):
                 self._cached_client = cli
 
         except barbican_exc.HTTPAuthError as e:
-            LOG.exception(e.message)
-            raise errors.BarbicanException(message=e.message,
-                                           code=e.status_code)
+            LOG.exception(str(e))
+            raise errors.BarbicanException(details=str(e))
 
         return cli
 

deckhand/barbican/driver.py

@@ -36,9 +36,8 @@ class BarbicanDriver(object):
         except (barbicanclient.exceptions.HTTPAuthError,
                 barbicanclient.exceptions.HTTPClientError,
                 barbicanclient.exceptions.HTTPServerError) as e:
-            LOG.exception(e.message)
-            raise errors.BarbicanException(message=e.message,
-                                           code=e.status_code)
+            LOG.exception(str(e))
+            raise errors.BarbicanException(details=str(e))
 
         # NOTE(fmontei): The dictionary representation of the Secret object by
         # default has keys that are not snake case -- so make them snake case.

deckhand/errors.py

@@ -356,16 +356,6 @@ class SubstitutionSourceNotFound(DeckhandException):
     code = 409
 
 
-class BarbicanException(DeckhandException):
-    """An error occurred with Barbican.
-
-    **Troubleshoot:**
-    """
-
-    def __init__(self, message, code):
-        super(BarbicanException, self).__init__(message=message, code=code)
-
-
 class PolicyNotAuthorized(DeckhandException):
     """The policy action is not found in the list of registered rules.
 
@@ -375,6 +365,21 @@ class PolicyNotAuthorized(DeckhandException):
     code = 403
 
 
+class BarbicanException(DeckhandException):
+    """An error occurred with Barbican.
+
+    **Troubleshoot:**
+
+    * Ensure that Deckhand can authenticate against Keystone.
+    * Ensure that Deckhand's Barbican configuration options are correct.
+    * Ensure that Deckhand and Barbican are contained in the Keystone service
+      catalog.
+    """
+    msg_fmt = ('An exception occurred while trying to communicate with '
+               'Barbican. Details: %(details)s')
+    code = 500
+
+
 class UnknownSubstitutionError(DeckhandException):
     """An unknown error occurred during substitution.