[OVN] Sync the LRP Gateway_Chassis with the network HCG

If a network with external ports is connected to a router (as an
internal network), Neutron will create a single ``HA_Chassis_Group``
register for this network, synced with the gateway
``Logical_Router_Port`` ``Gateway_Chassis`` registers. That will
schedule the external ports in the same chassis as the gateway port.

This patch attends any ``Gateway_Chassis`` change in order to sync
the attached networks ``HA_Chassis_Group`` registers, mimicking what
is defined the gateway port ``Gateway_Chassis`` list.

NOTE: This patch closes the list of patches that implement the
functionality defined in LP#2125553.

Closes-Bug: #2125553
Signed-off-by: Rodolfo Alonso Hernandez <ralonsoh@redhat.com>
Change-Id: Id75fcf72715f9b61aaa0487cdea192e8f9634fd1

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

@@ -89,6 +89,15 @@ class ChassisEvent(row_event.RowEvent):
                 'HA_Chassis_Group').execute(check_error=True):
             if not hcg.name.startswith(ovn_const.OVN_NAME_PREFIX):
                 continue
+
+            net_id = hcg.external_ids.get(ovn_const.OVN_NETWORK_ID_EXT_ID_KEY)
+            router_id = hcg.external_ids.get(
+                ovn_const.OVN_ROUTER_ID_EXT_ID_KEY)
+            if net_id and router_id:
+                # This HA_Chassis_Group is linked to a router, it will be
+                # updated matching the router Gateway_Chassis registers.
+                continue
+
             # The filter() is to get rid of the empty string in
             # the list that is returned because of split()
             azs = {az for az in

neutron/services/ovn_l3/ovsdb_monitor.py

@@ -75,3 +75,32 @@ class LogicalRouterPortEvent(row_event.RowEvent):
             else:  # LRP gateway port.
                 self.l3_plugin._ovn_client.update_router_ha_chassis_group(
                     self.admin_context, router_id)
+
+
+class LogicalRouterPortGatewayChassisEvent(row_event.RowEvent):
+    """Logical_Router_Port Gateway_Chassis change event.
+
+    When the Gateway_Chassis list of a Logical_Router_Port changes, it is
+    needed to update the linked HA_Chassis_Group registers.
+    """
+    def __init__(self, driver):
+        self.driver = driver
+        self.l3_plugin = directory.get_plugin(constants.L3)
+        self.admin_context = neutron_context.get_admin_context()
+        table = 'Logical_Router_Port'
+        events = (self.ROW_UPDATE, )
+        super().__init__(events, table, None)
+
+    def match_fn(self, event, row, old):
+        if hasattr(old, 'gateway_chassis'):
+            # NOTE: when a Gateway_Chassis register is deleted, is no longer
+            # present in the old.gateway_chassis list.
+            return True
+
+        return False
+
+    def run(self, event, row, old=None):
+        lr_name = row.external_ids.get(ovn_const.OVN_ROUTER_NAME_EXT_ID_KEY)
+        router_id = utils.get_neutron_name(lr_name)
+        self.l3_plugin._ovn_client.update_router_ha_chassis_group(
+            self.admin_context, router_id)

neutron/services/ovn_l3/plugin.py

@@ -179,6 +179,7 @@ class OVNL3RouterPlugin(service_base.ServicePluginBase,
         # Register needed events.
         self._nb_ovn.idl.notify_handler.watch_events([
             ovsdb_monitor.LogicalRouterPortEvent(self),
+            ovsdb_monitor.LogicalRouterPortGatewayChassisEvent(self),
         ])
 
     def _add_neutron_router_interface(self, context, router_id,

neutron/tests/functional/services/ovn_l3/test_ovsdb_monitor.py

@@ -18,6 +18,7 @@ from neutron_lib.api.definitions import external_net
 from neutron_lib.plugins import constants as plugin_constants
 from neutron_lib.plugins import directory
 
+from neutron.common.ovn import utils as ovn_utils
 from neutron.common import utils as n_utils
 from neutron.tests.functional import base
 from neutron.tests.unit.api import test_extensions
@@ -101,3 +102,80 @@ class TestLogicalRouterPortEvent(
             self._router_interface_action(
                 'remove', self.router_id, self.subnet_id, None)
             n_utils.wait_until_true(is_called, timeout=10)
+
+    def test_delete_router(self):
+        # The ``Logical_Router`` deletion triggers the
+        # ``LogicalRouterPortEvent`` event, but nothing is executed/called.
+        def is_called():
+            try:
+                mock_update_router.assert_called_once_with(
+                    mock.ANY, self.router_id)
+                return True
+            except AssertionError:
+                return False
+
+        with mock.patch.object(
+                self.l3_plugin._ovn_client,
+                'update_router_ha_chassis_group') as mock_update_router:
+            self._add_external_gateway_to_router(self.router_id,
+                                                 self.net_ext_id)
+            n_utils.wait_until_true(is_called, timeout=10)
+            mock_update_router.reset_mock()
+            req = self.new_delete_request('routers', self.router_id)
+            req.get_response(self.api)
+            self.assertRaises(n_utils.WaitTimeout, n_utils.wait_until_true,
+                              is_called, timeout=5)
+
+
+class TestLogicalRouterPortGatewayChassisEvent(
+    base.TestOVNFunctionalBase,
+    test_l3.L3NatTestCaseMixin):
+
+    def setUp(self, **kwargs):
+        super().setUp(**kwargs)
+        self.chassis = self.add_fake_chassis('ovs-host1')
+        self.l3_plugin = directory.get_plugin(plugin_constants.L3)
+        self.l3_plugin._post_fork_initialize(mock.ANY, mock.ANY, mock.ANY)
+        self.ext_api = test_extensions.setup_extensions_middleware(
+            test_l3.L3TestExtensionManager())
+        kwargs = {'arg_list': (external_net.EXTERNAL,),
+                  external_net.EXTERNAL: True}
+        self.net_ext = self._make_network(
+            self.fmt, 'net_ext', True, as_admin=True, **kwargs)
+        self.subnet = self._make_subnet(self.fmt, self.net_ext, '20.0.10.1',
+                                        '20.0.10.0/24')
+        self.router = self._make_router(self.fmt, self._tenant_id)
+        self.router_id = self.router['router']['id']
+        self.net_ext_id = self.net_ext['network']['id']
+        self.subnet_id = self.subnet['subnet']['id']
+
+    def test_add_and_remove_gateway_chassis(self):
+        def is_called():
+            try:
+                mock_update_router.assert_called_once_with(
+                    mock.ANY, self.router_id)
+                return True
+            except AssertionError:
+                return False
+
+        ch_list = []
+        for idx in range(5):
+            ch_list.append(self.add_fake_chassis(f'host-{idx}'))
+        self._add_external_gateway_to_router(self.router_id, self.net_ext_id)
+        lr = self.l3_plugin._nb_ovn.lookup('Logical_Router',
+                                           ovn_utils.ovn_name(self.router_id))
+        lrp_gw = lr.ports[0]
+        with mock.patch.object(
+                self.l3_plugin._ovn_client,
+                'update_router_ha_chassis_group') as mock_update_router:
+            for ch_name in ch_list:
+                self.l3_plugin._nb_ovn.lrp_set_gateway_chassis(
+                    lrp_gw.uuid, ch_name).execute(check_error=True)
+                n_utils.wait_until_true(is_called, timeout=10)
+                mock_update_router.reset_mock()
+
+            for ch_name in ch_list:
+                self.l3_plugin._nb_ovn.lrp_del_gateway_chassis(
+                    lrp_gw.uuid, ch_name).execute(check_error=True)
+                n_utils.wait_until_true(is_called, timeout=10)
+                mock_update_router.reset_mock()