Use agent chassis table based on schema

The patch determines a table that should be used for the agent API
in the runtime, based on the current available schema. It means OVN
database can be updated or downgraded while neutron-server is running
and agents will always report its liveness based on currently available
tables.

Change-Id: I679945b68acf391901c8602fb1828c46cd1eec55
Closes-bug: #1901527
Signed-off-by: Jakub Libosvar <libosvar@redhat.com>

lower-constraints.txt

@@ -79,7 +79,7 @@ oslo.versionedobjects==1.35.1
 oslotest==3.2.0
 osprofiler==2.3.0
 ovs==2.10.0
-ovsdbapp==1.6.0
+ovsdbapp==1.7.0
 packaging==20.4
 Paste==2.0.2
 PasteDeploy==1.5.0

neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovsdb_monitor.py

@@ -545,8 +545,30 @@ class OvnIdlDistributedLock(BaseOvnIdl):
         self._hash_ring = hash_ring_manager.HashRingManager(
             self.driver.hash_ring_group)
         self._last_touch = None
+        # This is a map of tables that may be new after OVN database is updated
+        self._tables_to_register = {
+            'OVN_Southbound': ['Chassis_Private'],
+        }
+
+    def handle_db_schema_changes(self, event, row):
+        if (event == row_event.RowEvent.ROW_CREATE and
+                row._table.name == 'Database'):
+            try:
+                tables = self._tables_to_register[row.name]
+            except KeyError:
+                return
+
+            self.update_tables(tables, row.schema[0])
+
+            if 'Chassis_Private' == self.driver.agent_chassis_table:
+                if 'Chassis_Private' not in self.tables:
+                    self.driver.agent_chassis_table = 'Chassis'
+            else:
+                if 'Chassis_Private' in self.tables:
+                    self.driver.agent_chassis_table = 'Chassis_Private'
 
     def notify(self, event, row, updates=None):
+        self.handle_db_schema_changes(event, row)
         self.notify_handler.notify(event, row, updates, global_=True)
         try:
             target_node = self._hash_ring.get_node(str(row.uuid))

neutron/tests/unit/plugins/ml2/drivers/ovn/mech_driver/ovsdb/test_ovsdb_monitor.py

@@ -219,6 +219,8 @@ class TestOvnIdlDistributedLock(base.BaseTestCase):
         self.mock_get_node = mock.patch.object(
             hash_ring_manager.HashRingManager,
             'get_node', return_value=self.node_uuid).start()
+        self.mock_update_tables = mock.patch.object(
+            self.idl, 'update_tables').start()
 
     def _assert_has_notify_calls(self):
         self.idl.notify_handler.notify.assert_has_calls([
@@ -279,6 +281,69 @@ class TestOvnIdlDistributedLock(base.BaseTestCase):
         self.idl.notify_handler.notify.assert_called_once_with(
             self.fake_event, self.fake_row, None, global_=True)
 
+    @staticmethod
+    def _create_fake_row(table_name):
+        # name is a parameter in Mock() so it can't be passed to constructor
+        table = mock.Mock()
+        table.name = table_name
+        return fakes.FakeOvsdbRow.create_one_ovsdb_row(
+            attrs={'_table': table, 'schema': ['foo']})
+
+    def test_handle_db_schema_changes_no_match_events(self):
+        other_table_row = self._create_fake_row('other')
+        database_table_row = self._create_fake_row('Database')
+
+        self.idl.handle_db_schema_changes(
+            ovsdb_monitor.BaseEvent.ROW_UPDATE, other_table_row)
+        self.idl.handle_db_schema_changes(
+            ovsdb_monitor.BaseEvent.ROW_CREATE, other_table_row)
+        self.idl.handle_db_schema_changes(
+            ovsdb_monitor.BaseEvent.ROW_UPDATE, database_table_row)
+
+        self.assertFalse(self.mock_update_tables.called)
+
+    def _test_handle_db_schema(self, agent_table, chassis_private_present):
+        database_table_row = self._create_fake_row('Database')
+        self.idl._tables_to_register[database_table_row.name] = 'foo'
+
+        self.fake_driver.agent_chassis_table = agent_table
+        if chassis_private_present:
+            self.idl.tables['Chassis_Private'] = 'foo'
+        else:
+            try:
+                del self.idl.tables['Chassis_Private']
+            except KeyError:
+                pass
+
+        self.idl.handle_db_schema_changes(
+            ovsdb_monitor.BaseEvent.ROW_CREATE, database_table_row)
+
+    def test_handle_db_schema_changes_old_schema_to_old_schema(self):
+        """Agents use Chassis and should keep using Chassis table"""
+        self._test_handle_db_schema('Chassis', chassis_private_present=False)
+        self.assertEqual('Chassis', self.fake_driver.agent_chassis_table)
+
+    def test_handle_db_schema_changes_old_schema_to_new_schema(self):
+        """Agents use Chassis and should start using Chassis_Private table"""
+        self._test_handle_db_schema('Chassis', chassis_private_present=True)
+        self.assertEqual('Chassis_Private',
+                         self.fake_driver.agent_chassis_table)
+
+    def test_handle_db_schema_changes_new_schema_to_old_schema(self):
+        """Agents use Chassis_Private and should start using Chassis table"""
+        self._test_handle_db_schema('Chassis_Private',
+                                    chassis_private_present=False)
+        self.assertEqual('Chassis', self.fake_driver.agent_chassis_table)
+
+    def test_handle_db_schema_changes_new_schema_to_new_schema(self):
+        """Agents use Chassis_Private and should keep using Chassis_Private
+           table.
+        """
+        self._test_handle_db_schema('Chassis_Private',
+                                    chassis_private_present=True)
+        self.assertEqual('Chassis_Private',
+                         self.fake_driver.agent_chassis_table)
+
 
 class TestPortBindingChassisUpdateEvent(base.BaseTestCase):
     def setUp(self):
@@ -319,6 +384,7 @@ class TestOvnNbIdlNotifyHandler(test_mech_driver.OVNMechanismDriverTestCase):
         self.lp_table = self.idl.tables.get('Logical_Switch_Port')
         self.driver.set_port_status_up = mock.Mock()
         self.driver.set_port_status_down = mock.Mock()
+        mock.patch.object(self.idl, 'handle_db_schema_changes').start()
 
     def _test_lsp_helper(self, event, new_row_json, old_row_json=None,
                          table=None):

requirements.txt

@@ -45,7 +45,7 @@ oslo.versionedobjects>=1.35.1 # Apache-2.0
 osprofiler>=2.3.0 # Apache-2.0
 os-ken >= 0.3.0 # Apache-2.0
 ovs>=2.10.0 # Apache-2.0
-ovsdbapp>=1.6.0 # Apache-2.0
+ovsdbapp>=1.7.0 # Apache-2.0
 packaging>=20.4  # Apache-2.0
 psutil>=5.3.0 # BSD
 pyroute2>=0.5.13;sys_platform!='win32' # Apache-2.0 (+ dual licensed GPL2)