Merge "Propagate AttributeErrors when lazily loading plugins"

openstackclient/common/clientmanager.py

@@ -22,8 +22,10 @@ import sys
 
 from oslo_utils import strutils
 import requests
+import six
 
 from openstackclient.api import auth
+from openstackclient.common import exceptions
 from openstackclient.common import session as osc_session
 from openstackclient.identity import client as identity_client
 
@@ -45,7 +47,13 @@ class ClientCache(object):
     def __get__(self, instance, owner):
         # Tell the ClientManager to login to keystone
         if self._handle is None:
-            self._handle = self.factory(instance)
+            try:
+                self._handle = self.factory(instance)
+            except AttributeError as err:
+                # Make sure the failure propagates. Otherwise, the plugin just
+                # quietly isn't there.
+                new_err = exceptions.PluginAttributeError(err)
+                six.reraise(new_err.__class__, new_err, sys.exc_info()[2])
         return self._handle
 
 

openstackclient/common/exceptions.py

@@ -24,6 +24,13 @@ class AuthorizationFailure(Exception):
     pass
 
 
+class PluginAttributeError(Exception):
+    """A plugin threw an AttributeError while being lazily loaded."""
+    # This *must not* inherit from AttributeError;
+    # that would defeat the whole purpose.
+    pass
+
+
 class NoTokenLookupException(Exception):
     """This does not support looking up endpoints from an existing token."""
     pass

openstackclient/tests/common/test_clientmanager.py

@@ -41,6 +41,7 @@ auth.get_options_list()
 
 class Container(object):
     attr = clientmanager.ClientCache(lambda x: object())
+    buggy_attr = clientmanager.ClientCache(lambda x: x.foo)
 
     def __init__(self):
         pass
@@ -72,6 +73,13 @@ class TestClientCache(utils.TestCase):
         c = Container()
         self.assertEqual(c.attr, c.attr)
 
+    def test_attribute_error_propagates(self):
+        c = Container()
+        err = self.assertRaises(exc.PluginAttributeError,
+                                getattr, c, 'buggy_attr')
+        self.assertNotIsInstance(err, AttributeError)
+        self.assertEqual("'Container' object has no attribute 'foo'", str(err))
+
 
 class TestClientManager(utils.TestCase):