Load additional config files for oslo.messaging options

Currently ceilometermiddleware supports customizing only the limited
number of oslo.messaging options via proxy-server.conf. However this
does not allow configurations required by some setups. For example when
TLS is enabled in RabbitMQ, the ssl option in RabbitMQ driver but this
option is not configurable now.

This introduces a few new options so that ceilometermiddleware can load
additional config files to look up oslo.messaging options.

Closes-Bug: #1673738
Change-Id: I0cae1a0daec189669e51f89231a3d7932784420e

ceilometermiddleware/swift.py

@@ -77,6 +77,7 @@ import queue
 import threading
 import urllib.parse as urlparse
 
+CONF = cfg.CONF
 LOG = logging.getLogger(__name__)
 
 
@@ -160,10 +161,26 @@ class Swift(object):
 
         self.ignore_projects = self._get_ignore_projects(conf)
 
+        extra_config_files = conf.get('extra_config_files')
+        if extra_config_files is not None:
+            extra_config_files = list_from_csv(extra_config_files)
+
+        extra_config_dirs = conf.get('extra_config_dirs')
+        if extra_config_dirs is not None:
+            extra_config_dirs = list_from_csv(extra_config_dirs)
+
+        try:
+            CONF(args=[], default_config_files=extra_config_files,
+                 default_config_dirs=extra_config_dirs)
+        except cfg.RequiredOptError:
+            # When authtoken middleware is enabled, CONF.__call__ fails because
+            # the required [keystone_authtoken] auth_url option is not set.
+            pass
+
         oslo_messaging.set_transport_defaults(conf.get('control_exchange',
                                                        'swift'))
         self._notifier = oslo_messaging.Notifier(
-            oslo_messaging.get_notification_transport(cfg.CONF,
+            oslo_messaging.get_notification_transport(CONF,
                                                       url=conf.get('url')),
             publisher_id='ceilometermiddleware',
             driver=conf.get('driver', 'messagingv2'),

releasenotes/notes/bug-1673738-ec8f7dd8ac43ad54.yaml

@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    The ceilometer middleware now supports loading additional config files to
+    look up oslo.messaging lbirary options. Set the ``extra_config_files``
+    parameter or the ``extra_config_dirs`` parameter in the ceilometer
+    middleware section in the swift proxy server config file.