Added ability to select identity interface

Extent configuration options to allow communicating with identity
over interface different than public.

Closes-Bug: #2105987
Change-Id: I3c2cb65337afc2cddd2a4771545139d470540a06

oslo_limit/limit.py

@@ -40,7 +40,10 @@ def _get_keystone_connection():
                 CONF, group='oslo_limit')
             session = loading.load_session_from_conf_options(
                 CONF, group='oslo_limit', auth=auth)
-            _SDK_CONNECTION = connection.Connection(session=session).identity
+            _SDK_CONNECTION = connection.Connection(
+                session=session,
+                interface=CONF.oslo_limit.interface
+            ).identity
         except (ksa_exceptions.NoMatchingPlugin,
                 ksa_exceptions.MissingRequiredOptions,
                 ksa_exceptions.MissingAuthPlugin,

oslo_limit/opts.py

@@ -43,6 +43,11 @@ _options = [
         choices=['public', 'publicURL', 'internal', 'internalURL',
                  'admin', 'adminURL'],
         help=_("The interface for endpoint discovery")),
+    cfg.StrOpt(
+        'interface',
+        default='public',
+        choices=['public', 'internal', 'admin'],
+        help=_("The interface used for communication with identity service.")),
 ]
 
 _option_group = 'oslo_limit'

releasenotes/notes/ability-to-select-interface-for-obtaining-limits-bae308e3d2f515f0.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    Added option ``interface`` to ``[oslo_limit]`` section, introducing ability
+    to select interface for communicating with identity service for obtaining
+    limits.