Add name parameter to NoMatchingPlugin exception

If you want to handle a NoMatchingPlugin exception rather than simply
exit then the name of the missing plugin is generally more useful than
the message.

The exception is specific enough that you can know what went wrong, but
you cannot determine the name of the missing plugin if you want to do
your own logging - only use the message that is generated.

We should keep the message but expose the plugin name as well.

Closes-Bug: #1410391
Change-Id: Ic93ec6583b8d7797529d36d63995ef0d8db754f1

keystoneclient/auth/base.py

@@ -17,7 +17,6 @@ import six
 import stevedore
 
 from keystoneclient import exceptions
-from keystoneclient.i18n import _
 
 
 # NOTE(jamielennox): The AUTH_INTERFACE is a special value that can be
@@ -44,8 +43,7 @@ def get_plugin_class(name):
                                       name=name,
                                       invoke_on_load=False)
     except RuntimeError:
-        msg = _('The plugin %s could not be found') % name
-        raise exceptions.NoMatchingPlugin(msg)
+        raise exceptions.NoMatchingPlugin(name)
 
     return mgr.driver
 

keystoneclient/exceptions.py

@@ -81,8 +81,19 @@ class MissingAuthPlugin(ClientException):
 class NoMatchingPlugin(ClientException):
     """There were no auth plugins that could be created from the parameters
     provided.
+
+    :param str name: The name of the plugin that was attempted to load.
+
+    .. py:attribute:: name
+
+        The name of the plugin that was attempted to load.
     """
 
+    def __init__(self, name):
+        self.name = name
+        msg = _('The plugin %s could not be found') % name
+        super(NoMatchingPlugin, self).__init__(msg)
+
 
 class InvalidResponse(ClientException):
     """The response from the server is not valid for this request."""

keystoneclient/tests/auth/test_conf.py

@@ -92,13 +92,16 @@ class ConfTests(utils.TestCase):
         self.assertEqual(project_domain_name, a.project_domain_name)
 
     def test_loading_invalid_plugin(self):
-        self.conf_fixture.config(auth_plugin=uuid.uuid4().hex,
+        auth_plugin = uuid.uuid4().hex
+        self.conf_fixture.config(auth_plugin=auth_plugin,
                                  group=self.GROUP)
 
-        self.assertRaises(exceptions.NoMatchingPlugin,
-                          conf.load_from_conf_options,
-                          self.conf_fixture.conf,
-                          self.GROUP)
+        e = self.assertRaises(exceptions.NoMatchingPlugin,
+                              conf.load_from_conf_options,
+                              self.conf_fixture.conf,
+                              self.GROUP)
+
+        self.assertEqual(auth_plugin, e.name)
 
     def test_loading_with_no_data(self):
         self.assertIsNone(conf.load_from_conf_options(self.conf_fixture.conf,