2 files changed, 76 insertions, 7 deletions
diff --git a/keystoneclient/auth/base.py b/keystoneclient/auth/base.py
index a6c54f1..91cf86a 100644
--- a/keystoneclient/auth/base.py
+++ b/keystoneclient/auth/base.py
@@ -255,13 +255,11 @@ class BaseAuthPlugin(object):
         :returns: An auth plugin, or None if a name is not provided.
         :rtype: :py:class:`keystoneclient.auth.BaseAuthPlugin`
         """
-        for opt in cls.get_options():
-            val = getattr(namespace, 'os_%s' % opt.dest)
-            if val is not None:
-                val = opt.type(val)
-            kwargs.setdefault(opt.dest, val)
 
-        return cls.load_from_options(**kwargs)
+        def _getter(opt):
+            return getattr(namespace, 'os_%s' % opt.dest)
+
+        return cls.load_from_options_getter(_getter, **kwargs)
 
     @classmethod
     def register_conf_options(cls, conf, group):
@@ -287,10 +285,34 @@ class BaseAuthPlugin(object):
         :returns: An authentication Plugin.
         :rtype: :py:class:`keystoneclient.auth.BaseAuthPlugin`
         """
+
+        def _getter(opt):
+            return conf[group][opt.dest]
+
+        return cls.load_from_options_getter(_getter, **kwargs)
+
+    @classmethod
+    def load_from_options_getter(cls, getter, **kwargs):
+        """Load a plugin from a getter function that returns appropriate values
+
+        To handle cases other than the provided CONF and CLI loading you can
+        specify a custom loader function that will be queried for the option
+        value.
+
+        The getter is a function that takes one value, an
+        :py:class:`oslo_config.cfg.Opt` and returns a value to load with.
+
+        :param getter: A function that returns a value for the given opt.
+        :type getter: callable
+
+        :returns: An authentication Plugin.
+        :rtype: :py:class:`keystoneclient.auth.BaseAuthPlugin`
+        """
+
         plugin_opts = cls.get_options()
 
         for opt in plugin_opts:
-            val = conf[group][opt.dest]
+            val = getter(opt)
             if val is not None:
                 val = opt.type(val)
             kwargs.setdefault(opt.dest, val)
diff --git a/keystoneclient/tests/unit/auth/test_loading.py b/keystoneclient/tests/unit/auth/test_loading.py
new file mode 100644
index 0000000..f8ef3b7
--- /dev/null
+++ b/keystoneclient/tests/unit/auth/test_loading.py
@@ -0,0 +1,47 @@
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import uuid
+
+import six
+
+from keystoneclient.tests.unit.auth import utils
+
+
+class TestOtherLoading(utils.TestCase):
+
+    def test_loading_getter(self):
+
+        called_opts = []
+
+        vals = {'a-int': 44,
+                'a-bool': False,
+                'a-float': 99.99,
+                'a-str': 'value'}
+
+        val = uuid.uuid4().hex
+
+        def _getter(opt):
+            called_opts.append(opt.name)
+            # return str because oslo.config should convert them back
+            return str(vals[opt.name])
+
+        p = utils.MockPlugin.load_from_options_getter(_getter, other=val)
+
+        self.assertEqual(set(vals), set(called_opts))
+
+        for k, v in six.iteritems(vals):
+            # replace - to _ because it's the dest used to create kwargs
+            self.assertEqual(v, p[k.replace('-', '_')])
+
+        # check that additional kwargs get passed through
+        self.assertEqual(val, p['other'])