NSX|V update router edge when gateway subnet changes

When a subnet gateway changes, and this subnet is the gateway of a router
we need to update the next hop on the router edge

Change-Id: If232ac89c880e8a501466abbfaae7b954609aa0d

vmware_nsx/plugins/nsx_v/drivers/abstract_router_driver.py

@@ -127,3 +127,7 @@ class RouterBaseDriver(RouterAbstractDriver):
     def get_router_az_by_id(self, context, router_id):
         lrouter = self.plugin.get_router(context, router_id)
         return self.get_router_az(lrouter)
+
+    def _update_nexthop(self, context, router_id, newnexthop):
+        """Update the router edge on gateway subnet default gateway change."""
+        self.plugin._update_routes(context, router_id, newnexthop)

vmware_nsx/plugins/nsx_v/drivers/distributed_router_driver.py

@@ -147,6 +147,12 @@ class RouterDistributedDriver(router_driver.RouterBaseDriver):
             self._update_routes_on_tlr(context, router_id, newnexthop=None,
                                        metadata_gateway=metadata_gateway)
 
+    def _update_nexthop(self, context, router_id, newnexthop):
+        plr_id = self.edge_manager.get_plr_by_tlr_id(context, router_id)
+        if plr_id:
+            self._update_routes_on_plr(context, router_id, plr_id,
+                                       newnexthop)
+
     def _update_router_gw_info(self, context, router_id, info,
                                is_routes_update=False,
                                force_update=False):

vmware_nsx/plugins/nsx_v/plugin.py

@@ -2030,6 +2030,18 @@ class NsxVPluginV2(addr_pair_db.AllowedAddressPairsMixin,
             update_dhcp_config = True
         return update_dhcp_config
 
+    def _update_routers_on_gateway_change(self, context, subnet_id,
+                                          new_gateway):
+        """Update all relevant router edges that the nexthop changed."""
+        port_filters = {'device_owner': [l3_db.DEVICE_OWNER_ROUTER_GW],
+                        'fixed_ips': {'subnet_id': [subnet_id]}}
+        intf_ports = self.get_ports(context.elevated(),
+                                    filters=port_filters)
+        router_ids = [port['device_id'] for port in intf_ports]
+        for router_id in router_ids:
+            router_driver = self._find_router_driver(context, router_id)
+            router_driver._update_nexthop(context, router_id, new_gateway)
+
     def update_subnet(self, context, id, subnet):
         s = subnet['subnet']
         orig = self._get_subnet(context, id)
@@ -2053,6 +2065,10 @@ class NsxVPluginV2(addr_pair_db.AllowedAddressPairsMixin,
             # Update the edge
             network_id = subnet['network_id']
             self.edge_manager.update_dhcp_edge_bindings(context, network_id)
+            # also update routers that use this subnet as their gateway
+            if gateway_ip != subnet['gateway_ip']:
+                self._update_routers_on_gateway_change(context, id,
+                                                       subnet['gateway_ip'])
         if enable_dhcp != subnet['enable_dhcp']:
             self._update_subnet_dhcp_status(subnet, context)
         return subnet

vmware_nsx/tests/unit/nsx_v/test_plugin.py

@@ -64,6 +64,8 @@ from vmware_nsx.extensions import routertype as router_type
 from vmware_nsx.extensions import securitygrouplogging
 from vmware_nsx.extensions import vnicindex as ext_vnic_idx
 from vmware_nsx.plugins.nsx_v import availability_zones as nsx_az
+from vmware_nsx.plugins.nsx_v.drivers import (
+    distributed_router_driver as dist_router_driver)
 from vmware_nsx.plugins.nsx_v.drivers import (
     exclusive_router_driver as ex_router_driver)
 from vmware_nsx.plugins.nsx_v.drivers import (
@@ -3144,6 +3146,17 @@ class TestExclusiveRouterTestCase(L3NatTest, L3NatTestCaseBase,
     def test_router_add_gateway_multiple_subnets_ipv6(self):
         self.skipTest('not supported')
 
+    def test_update_subnet_gateway_for_external_net(self):
+        plugin = directory.get_plugin()
+        router_obj = ex_router_driver.RouterExclusiveDriver(plugin)
+        with mock.patch.object(plugin, '_find_router_driver',
+                               return_value=router_obj):
+            with mock.patch.object(router_obj,
+                                   '_update_nexthop') as update_nexthop:
+                super(TestExclusiveRouterTestCase,
+                      self).test_update_subnet_gateway_for_external_net()
+                self.assertTrue(update_nexthop.called)
+
 
 class ExtGwModeTestCase(NsxVPluginV2TestCase,
                         test_ext_gw_mode.ExtGwModeIntTestCase):
@@ -3671,6 +3684,17 @@ class TestVdrTestCase(L3NatTest, L3NatTestCaseBase,
     def test_floatingip_update_to_same_port_id_twice(self):
         self.skipTest('Plugin changes floating port status')
 
+    def test_update_subnet_gateway_for_external_net(self):
+        plugin = directory.get_plugin()
+        router_obj = dist_router_driver.RouterDistributedDriver(plugin)
+        with mock.patch.object(plugin, '_find_router_driver',
+                               return_value=router_obj):
+            with mock.patch.object(router_obj,
+                                   '_update_nexthop') as update_nexthop:
+                super(TestVdrTestCase,
+                      self).test_update_subnet_gateway_for_external_net()
+                self.assertTrue(update_nexthop.called)
+
 
 class TestNSXvAllowedAddressPairs(NsxVPluginV2TestCase,
                                   test_addr_pair.TestAllowedAddressPairs):