When deleting floating IP catch PortNotFound

If we try to delete a VM and to delete the floating IP
associated with the VM at the same time, depending
on the order according to which these requests are processed
Neutron might fail in the deletion of the floating IP,
raising a PortNotFound error. This happens because Neutron
notifies Nova of the network change event and it tries to get
the port to which the FIP is associated. If the port is not there,
Neutron shouldn't raise, it shouldn't send any notification.

Conflicts:
	neutron/notifiers/nova.py
	neutron/tests/unit/notifiers/test_nova.py

Closes-bug: #1586931
Change-Id: Ic72313ad1f787b3cb528e806c843f1fd01eb12f2
(cherry picked from commit 6e275e3857)

neutron/notifiers/nova.py

@@ -24,6 +24,7 @@ from oslo_utils import uuidutils
 from sqlalchemy.orm import attributes as sql_attr
 
 from neutron.common import constants
+from neutron.common import exceptions as exc
 from neutron import context
 from neutron.i18n import _LE, _LI, _LW
 from neutron import manager
@@ -177,7 +178,12 @@ class Notifier(object):
                 return
 
             ctx = context.get_admin_context()
-            port = self._plugin.get_port(ctx, port_id)
+            try:
+                port = self._plugin.get_port(ctx, port_id)
+            except exc.PortNotFound:
+                LOG.debug("Port %s was deleted, no need to send any "
+                          "notification", port_id)
+                return
 
         if port and self._is_compute_port(port):
             if action == 'delete_port':

neutron/tests/unit/notifiers/test_nova.py

@@ -22,6 +22,7 @@ from sqlalchemy.orm import attributes as sql_attr
 from oslo_config import cfg
 
 from neutron.common import constants
+from neutron.common import exceptions as n_exc
 from neutron.db import models_v2
 from neutron.notifiers import nova
 from neutron.tests import base
@@ -172,6 +173,17 @@ class TestNovaNotify(base.BaseTestCase):
             'delete_floatingip', {}, returned_obj)
         self.assertEqual(expected_event, event)
 
+    def test_delete_floatingip_deleted_port_no_notify(self):
+        port_id = 'bee50827-bcee-4cc8-91c1-a27b0ce54222'
+        with mock.patch.object(
+            self.nova_notifier._plugin_ref, 'get_port',
+            side_effect=n_exc.PortNotFound(port_id=port_id)):
+            returned_obj = {'floatingip':
+                            {'port_id': port_id}}
+            event = self.nova_notifier.create_port_changed_event(
+                'delete_floatingip', {}, returned_obj)
+            self.assertIsNone(event)
+
     def test_delete_floatingip_no_port_id_no_notify(self):
         returned_obj = {'floatingip':
                         {'port_id': None}}