ML2: Call _dict_extend in create_(net|port) ops

The extensions fields were not being added to the response being
sent back to the user for ports and networks that weren't from
ML2 extensions (e.g. availability zones). This created an
inconsistent response between creates and updates/gets. It also
resulted in incomplete data in the AMQP create notification emitted
in the API layer.

This patch adjusts ML2 to call the _apply_dict_extend_functions
method after creating ports and networks. To make this work, another
DB lookup to get the latest model state was necessary. However, this
is part of an already expensive operation (create) so the performance
impact should be minimal.

This issue stems from the fact that db_base_plugin_v2 does not
process extensions when its create_port, create_network methods
are called. This original skipping behavior was added back in
patch If0f0277191884aab4dcb1ee36826df7f7d66a8fa as a performance
improvement to deal with dictionary extension functions that
performed DB lookups. However, at this point the dictionary
extension functions should have been optimized to skip any DB
lookups to avoid the massive performance penalties they incur
during list operations.

An alternative to this patch was to adjust the db_base_plugin_v2
to stop skipping extensions. However, because this is usually
called by inheriting plugins before they process extensions
for the new port/network, the extensions do not yet have the
required information to extend the dict and will fail. So each
core plugin will need to apply similar logic to support extensions
that rely on the extend_dict functions.

Closes-Bug: #1541774
Change-Id: Iea2c0e7f9ee5eeae28b99797874ca8a8e5790ec2

neutron/plugins/ml2/plugin.py

@@ -671,6 +671,10 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                     result['id'], {'network': {'vlan_transparent': vlt}})
                 result['vlan_transparent'] = vlt
 
+        # NOTE(kevinbenton): this extra lookup is necessary to get the
+        # latest db model for the extension functions
+        net_model = self._get_network(context, result['id'])
+        self._apply_dict_extend_functions('networks', result, net_model)
         return result, mech_context
 
     def create_network(self, context, network):
@@ -1063,6 +1067,10 @@ class Ml2Plugin(db_base_plugin_v2.NeutronDbPluginV2,
                                                       dhcp_opts)
             self.mechanism_manager.create_port_precommit(mech_context)
 
+        # NOTE(kevinbenton): this extra lookup is necessary to get the
+        # latest db model for the extension functions
+        port_model = self._get_port(context, result['id'])
+        self._apply_dict_extend_functions('ports', result, port_model)
         return result, mech_context
 
     def create_port(self, context, port):

neutron/tests/unit/extensions/test_availability_zone.py

@@ -98,6 +98,11 @@ class TestAZNetworkCase(AZTestCommon):
         ext_mgr = AZExtensionManager()
         super(TestAZNetworkCase, self).setUp(plugin=plugin, ext_mgr=ext_mgr)
 
+    def test_availability_zones_in_create_response(self):
+        with self.network() as net:
+            self.assertIn('availability_zone_hints', net['network'])
+            self.assertIn('availability_zones', net['network'])
+
     def test_create_network_with_az(self):
         self._register_azs()
         az_hints = ['nova1']

neutron/tests/unit/plugins/ml2/test_extension_driver_api.py

@@ -81,7 +81,7 @@ class ExtensionDriverTestCase(test_plugin.Ml2PluginV2TestCase):
     def test_faulty_extend_dict(self):
         with mock.patch.object(ext_test.TestExtensionDriver,
                                'extend_network_dict',
-                               side_effect=[None, TypeError]):
+                               side_effect=[None, None, TypeError]):
             network, tid = self._verify_network_create(201, None)
             self._verify_network_update(network, 400, 'ExtensionDriverError')