add a log when the option in conf can't be identitied

When the option is unknown to auth_token and it's value can't be
converted, this patch adds a warning log.

Change-Id: I818708cc19488030b80daa2b01b9f8622632f7eb

keystonemiddleware/_common/config.py

@@ -13,6 +13,7 @@
 import pkg_resources
 
 from oslo_config import cfg
+from oslo_log import log as logging
 import pbr
 import six
 
@@ -21,6 +22,7 @@
 
 CONF = cfg.CONF
 _NOT_SET = object()
+_LOG = logging.getLogger(__name__)
 
 
 def _conf_values_type_convert(group_name, all_options, conf):
@@ -53,8 +55,8 @@ def _conf_values_type_convert(group_name, all_options, conf):
                 v = type_(v)
         except KeyError:  # nosec
             # This option is not known to auth_token. v is not converted.
-            # FIXME(jamielennox): This should probably log a warning.
-            pass
+            _LOG.warning(
+                'The option "%s" in conf is not known to auth_token', k)
         except ValueError as e:
             raise exceptions.ConfigurationError(
                 _('Unable to convert the value of %(key)s option into correct '

keystonemiddleware/tests/unit/auth_token/test_auth_token_middleware.py

@@ -491,6 +491,14 @@ def test_deprecated_conf_values(self):
         middleware = auth_token.AuthProtocol(self.fake_app, conf)
         self.assertEqual([servers], middleware._conf.get('memcached_servers'))
 
+    def test_conf_values_type_convert_with_wrong_key(self):
+        conf = {
+            'wrong_key': '123'
+        }
+        log = 'The option "wrong_key" in conf is not known to auth_token'
+        auth_token.AuthProtocol(self.fake_app, conf)
+        self.assertThat(self.logger.output, matchers.Contains(log))
+
     def test_conf_values_type_convert_with_wrong_value(self):
         conf = {
             'include_service_catalog': '123',