From: armando-migliaccio <armamig@gmail.com>
Date: Fri, 21 Nov 2014 22:41:05 +0000 (-0800)
Subject: Fix AttributeError during startup of ovs agent in DVR mode
X-Git-Url: https://review.fuel-infra.org/gitweb?a=commitdiff_plain;h=aa728c00bab3bb6b3e00866e44ca054b1e848bb6;p=openstack-build%2Fneutron-build.git

Fix AttributeError during startup of ovs agent in DVR mode

Make sure the agent starts processing incoming requests only after the entire
initialization is complete. This is done by making explicit when the rpc loop
is supposed to start, i.e. right at the end of the init process.

This fix was necessary because the agent starts processing rpc messages even
though it has not completed the entire initialization of bridges and data
structures; this is usually okay, but in case of DVR, this leads to a
situation where during the the first run, the agent asks the server to be
assigned a MAC address; this in turn leads the server to fanout the generated
MAC to the running agents, the requesting one included; because of the
incomplete setup, the above mentioned error occurs. During subsequent
restarts, the problem no longer appears.

Closes-bug: #1395196

Change-Id: I792697b94fef39971693cf8aff715c270601cecb
---

diff --git a/neutron/agent/rpc.py b/neutron/agent/rpc.py
index 67ff168f7..98e641a59 100644
--- a/neutron/agent/rpc.py
+++ b/neutron/agent/rpc.py
@@ -26,7 +26,7 @@ from neutron.openstack.common import log as logging
 LOG = logging.getLogger(__name__)
 
 
-def create_consumers(endpoints, prefix, topic_details):
+def create_consumers(endpoints, prefix, topic_details, start_listening=True):
     """Create agent RPC consumers.
 
     :param endpoints: The list of endpoints to process the incoming messages.
@@ -34,6 +34,7 @@ def create_consumers(endpoints, prefix, topic_details):
     :param topic_details: A list of topics. Each topic has a name, an
                           operation, and an optional host param keying the
                           subscription to topic.host for plugin calls.
+    :param start_listening: if True, it starts the processing loop
 
     :returns: A common Connection.
     """
@@ -50,7 +51,8 @@ def create_consumers(endpoints, prefix, topic_details):
             connection.create_consumer(node_topic_name,
                                        endpoints,
                                        fanout=False)
-    connection.consume_in_threads()
+    if start_listening:
+        connection.consume_in_threads()
     return connection
 
 
diff --git a/neutron/plugins/openvswitch/agent/ovs_neutron_agent.py b/neutron/plugins/openvswitch/agent/ovs_neutron_agent.py
index 66227bd96..e2e9d54ec 100644
--- a/neutron/plugins/openvswitch/agent/ovs_neutron_agent.py
+++ b/neutron/plugins/openvswitch/agent/ovs_neutron_agent.py
@@ -259,6 +259,9 @@ class OVSNeutronAgent(sg_rpc.SecurityGroupAgentRpcCallbackMixin,
         self.iter_num = 0
         self.run_daemon_loop = True
 
+        # The initialization is complete; we can start receiving messages
+        self.connection.consume_in_threads()
+
     def _report_state(self):
         # How many devices are likely used by a VM
         self.agent_state.get('configurations')['devices'] = (
@@ -296,7 +299,8 @@ class OVSNeutronAgent(sg_rpc.SecurityGroupAgentRpcCallbackMixin,
                               topics.UPDATE, cfg.CONF.host])
         self.connection = agent_rpc.create_consumers(self.endpoints,
                                                      self.topic,
-                                                     consumers)
+                                                     consumers,
+                                                     start_listening=False)
 
     def get_net_uuid(self, vif_id):
         for network_id, vlan_mapping in self.local_vlan_map.iteritems():
diff --git a/neutron/tests/unit/test_agent_rpc.py b/neutron/tests/unit/test_agent_rpc.py
index ccabce161..0412868ec 100644
--- a/neutron/tests/unit/test_agent_rpc.py
+++ b/neutron/tests/unit/test_agent_rpc.py
@@ -117,7 +117,16 @@ class AgentPluginReportState(base.BaseTestCase):
 
 
 class AgentRPCMethods(base.BaseTestCase):
-    def test_create_consumers(self):
+
+    def _test_create_consumers(
+        self, endpoints, method, expected, topics, listen):
+        call_to_patch = 'neutron.common.rpc.create_connection'
+        with mock.patch(call_to_patch) as create_connection:
+            rpc.create_consumers(
+                endpoints, method, topics, start_listening=listen)
+            create_connection.assert_has_calls(expected)
+
+    def test_create_consumers_start_listening(self):
         endpoints = [mock.Mock()]
         expected = [
             mock.call(new=True),
@@ -125,11 +134,22 @@ class AgentRPCMethods(base.BaseTestCase):
                                         fanout=True),
             mock.call().consume_in_threads()
         ]
+        method = 'foo'
+        topics = [('topic', 'op')]
+        self._test_create_consumers(
+            endpoints, method, expected, topics, True)
 
-        call_to_patch = 'neutron.common.rpc.create_connection'
-        with mock.patch(call_to_patch) as create_connection:
-            rpc.create_consumers(endpoints, 'foo', [('topic', 'op')])
-            create_connection.assert_has_calls(expected)
+    def test_create_consumers_do_not_listen(self):
+        endpoints = [mock.Mock()]
+        expected = [
+            mock.call(new=True),
+            mock.call().create_consumer('foo-topic-op', endpoints,
+                                        fanout=True),
+        ]
+        method = 'foo'
+        topics = [('topic', 'op')]
+        self._test_create_consumers(
+            endpoints, method, expected, topics, False)
 
     def test_create_consumers_with_node_name(self):
         endpoints = [mock.Mock()]