Initialize MQ transport only once

There are two separate features that use MQ transport:
1. Ceilometer notifications
2. api-engine communication

Merged MQ initialization code for them.
The question "Should they use the same MQ or not?" is out of
scope of this CR.

Change-Id: I6a38708bce4c031f9e759a29afbce14325960808
Closes-Bug: #1413005

sahara/main.py

@@ -83,7 +83,8 @@ def setup_common(possible_topdir, service_name):
     # Validate other configurations (that may produce logs) here
     cinder.validate_config()
 
-    messaging.setup()
+    if service_name != 'all-in-one' or cfg.CONF.enable_notifications:
+        messaging.setup()
 
     if service_name != 'all-in-one':
         LOG.warn(

sahara/tests/unit/utils/notification/test_sender.py

@@ -52,7 +52,7 @@ class NotificationTest(base.SaharaTestCase):
     @mock.patch('oslo_messaging.notify.notifier.Notifier.info')
     def test_update_cluster(self, mock_notify):
         self.override_config("enable_notifications", True)
-        messaging.setup("fake://", optional=True)
+        messaging.setup()
 
         self._make_sample()
         self.assertEqual([self.expected],

sahara/tests/unit/utils/test_rpc.py

@@ -33,7 +33,7 @@ class TestMessagingSetup(base.SaharaTestCase):
         self.override_config('enable_notifications', True)
 
     def _install(self):
-        messaging.setup('fake://', optional=True)
+        messaging.setup()
         self.assertNotEqual(None, messaging.TRANSPORT)
         self.assertNotEqual(None, messaging.NOTIFIER)
 
@@ -58,7 +58,7 @@ class TestMessagingSetup(base.SaharaTestCase):
         self._install()
 
         expected = [
-            mock.call(main.CONF, 'fake://', aliases=_ALIASES)
+            mock.call(main.CONF, aliases=_ALIASES)
         ]
         self.assertEqual(expected, mock_transport.call_args_list)
 
@@ -68,11 +68,6 @@ class TestMessagingSetup(base.SaharaTestCase):
     def test_notifier(self, mock_init):
         self._install()
 
-        serializer = messaging.SERIALIZER
-        expected = [
-            mock.call(messaging.TRANSPORT, serializer=serializer)
-        ]
-
-        self.assertEqual(expected, mock_init.call_args_list)
+        self.assertEqual(1, mock_init.call_count)
 
         self._remove_install()

sahara/utils/rpc.py

@@ -25,7 +25,6 @@ from sahara.i18n import _LI
 
 TRANSPORT = None
 NOTIFIER = None
-SERIALIZER = None
 
 CONF = cfg.CONF
 LOG = logging.getLogger(__name__)
@@ -64,9 +63,11 @@ class JsonPayloadSerializer(messaging.NoOpSerializer):
 
 class RPCClient(object):
     def __init__(self, target):
+        global TRANSPORT
+
         self.__client = messaging.RPCClient(
             target=target,
-            transport=messaging.get_transport(cfg.CONF),
+            transport=TRANSPORT,
         )
 
     def cast(self, name, **kwargs):
@@ -80,9 +81,11 @@ class RPCClient(object):
 
 class RPCServer(object):
     def __init__(self, target):
+        global TRANSPORT
+
         self.__server = messaging.get_rpc_server(
             target=target,
-            transport=messaging.get_transport(cfg.CONF),
+            transport=TRANSPORT,
             endpoints=[self],
             executor='eventlet')
 
@@ -91,29 +94,21 @@ class RPCServer(object):
         self.__server.wait()
 
 
-def setup(url=None, optional=False):
+def setup():
     """Initialise the oslo_messaging layer."""
-    global TRANSPORT, NOTIFIER, SERIALIZER
+    global TRANSPORT, NOTIFIER
+
+    messaging.set_transport_defaults('sahara')
+
+    TRANSPORT = messaging.get_transport(cfg.CONF, aliases=_ALIASES)
 
     if not cfg.CONF.enable_notifications:
         LOG.info(_LI("Notifications disabled"))
         return
     LOG.info(_LI("Notifications enabled"))
 
-    messaging.set_transport_defaults('sahara')
-
-    SERIALIZER = ContextSerializer(JsonPayloadSerializer())
-
-    try:
-        TRANSPORT = messaging.get_transport(cfg.CONF, url,
-                                            aliases=_ALIASES)
-    except messaging.InvalidTransportURL as e:
-        TRANSPORT = None
-        if not optional or e.url:
-            raise
-
-    if TRANSPORT:
-        NOTIFIER = messaging.Notifier(TRANSPORT, serializer=SERIALIZER)
+    serializer = ContextSerializer(JsonPayloadSerializer())
+    NOTIFIER = messaging.Notifier(TRANSPORT, serializer=serializer)
 
 
 def get_notifier(publisher_id):