Maintenance: Re-create the metadata port

This patch adds a new task to the maintenance thread which re-creates
the metadata port in case it's been wrongly deleted (by whatever
reasons). The task will run immediately at service restart and fix those
ports, just like ml2/ovs would do with the DHCP ports.

Closes-Bug: #1813939
Change-Id: I0819c2b956dd41c8fe59a2b1b4fec9d229afb067
Signed-off-by: Lucas Alvares Gomes <lucasagomes@gmail.com>

networking_ovn/common/maintenance.py

@@ -366,3 +366,21 @@ class DBInconsistenciesPeriodics(object):
                  '(took %.2f seconds)', self._sync_timer.elapsed())
 
         raise periodics.NeverAgain()
+
+    # A static spacing value is used here, but this method will only run
+    # once per lock due to the use of periodics.NeverAgain().
+    @periodics.periodic(spacing=1800, run_immediately=True)
+    def check_metadata_ports(self):
+        # If OVN metadata is disabled do not run this task again
+        if not ovn_conf.is_ovn_metadata_enabled():
+            raise periodics.NeverAgain()
+
+        # Make sure that only one worker is executing this
+        if not self.has_lock:
+            return
+
+        admin_context = n_context.get_admin_context()
+        for n in self._ovn_client._plugin.get_networks(admin_context):
+            self._ovn_client.create_metadata_port(admin_context, n)
+
+        raise periodics.NeverAgain()

networking_ovn/tests/functional/test_maintenance.py

@@ -694,3 +694,44 @@ class TestMaintenance(_TestMaintenanceHelper):
 
         # Assert the revision number no longer exists
         self.assertIsNone(db_rev.get_revision_row(neutron_obj['port_id']))
+
+    def test_check_metadata_ports(self):
+        ovn_config.cfg.CONF.set_override('ovn_metadata_enabled', True,
+                                         group='ovn')
+        neutron_net = self._create_network('network1')
+        metadata_ports = self._ovn_client._get_metadata_ports(
+            self.context, neutron_net['id'])
+
+        # Assert the metadata port exists
+        self.assertEqual(1, len(metadata_ports))
+
+        # Delete the metadata port
+        self._delete('ports', metadata_ports[0]['id'])
+
+        metadata_ports = self._ovn_client._get_metadata_ports(
+            self.context, neutron_net['id'])
+
+        # Assert the metadata port is gone
+        self.assertEqual(0, len(metadata_ports))
+
+        # Call the maintenance thread to fix the problem, it will raise
+        # NeverAgain so that the job only runs once at startup
+        self.assertRaises(periodics.NeverAgain,
+                          self.maint.check_metadata_ports)
+
+        metadata_ports = self._ovn_client._get_metadata_ports(
+            self.context, neutron_net['id'])
+
+        # Assert the metadata port was re-created
+        self.assertEqual(1, len(metadata_ports))
+
+    def test_check_metadata_ports_not_enabled(self):
+        ovn_config.cfg.CONF.set_override('ovn_metadata_enabled', False,
+                                         group='ovn')
+        with mock.patch.object(self._ovn_client,
+                               'create_metadata_port') as mock_create_port:
+            self.assertRaises(periodics.NeverAgain,
+                              self.maint.check_metadata_ports)
+            # Assert create_metadata_port() wasn't called since metadata
+            # is not enabled
+            self.assertFalse(mock_create_port.called)