Add a method to retrieve router gateway ports

A method is added as opposed to having a synthetic field on a router for
performance reasons: gateways will only be queried when needed to use
the external gateways feature API calls.

Partial-Bug: #2002687
Change-Id: Iddde9d986b024109bdb7c2aa777a1b017b6a35ab

2 files changed, 40 insertions, 0 deletions

diff --git a/neutron/objects/router.py b/neutron/objects/router.py
index 2f1e314d93..f462a1b57c 100644
--- a/neutron/objects/router.py
+++ b/neutron/objects/router.py
@@ -163,6 +163,15 @@ class RouterPort(base.NeutronDbObject):
         query = query.distinct()
         return [r[0] for r in query]
 
+    @classmethod
+    @db_api.CONTEXT_READER
+    def get_gw_port_ids_by_router_id(cls, context, router_id):
+        query = context.session.query(l3.RouterPort)
+        query = query.filter(
+            l3.RouterPort.router_id == router_id,
+            l3.RouterPort.port_type == n_const.DEVICE_OWNER_ROUTER_GW)
+        return [rp.port_id for rp in query]
+
 
 @base.NeutronObjectRegistry.register
 class DVRMacAddress(base.NeutronDbObject):
diff --git a/neutron/tests/unit/objects/test_router.py b/neutron/tests/unit/objects/test_router.py
index 5c86aec2fc..f1886db0c8 100644
--- a/neutron/tests/unit/objects/test_router.py
+++ b/neutron/tests/unit/objects/test_router.py
@@ -17,6 +17,7 @@ from unittest import mock
 
 import netaddr
 
+from neutron_lib import constants
 from neutron_lib.db import api as db_api
 from oslo_utils import uuidutils
 
@@ -206,6 +207,36 @@ class RouterPortDbObjectTestCase(obj_test_base.BaseDbObjectTestCase,
             {'router_id': lambda: self._create_test_router_id(),
              'port_id': lambda: self._create_test_port_id()})
 
+    def test_get_gw_port_ids_by_router_id(self):
+        router_id = self._create_test_router_id()
+        router_gws = [
+            self._make_object({
+                'router_id': router_id,
+                'port_id': self._create_test_port_id(
+                    device_owner=constants.DEVICE_OWNER_ROUTER_GW),
+                'port_type': constants.DEVICE_OWNER_ROUTER_GW}),
+            self._make_object({
+                'router_id': router_id,
+                'port_id': self._create_test_port_id(
+                    device_owner=constants.DEVICE_OWNER_ROUTER_GW),
+                'port_type': constants.DEVICE_OWNER_ROUTER_GW,
+            })
+        ]
+        for gw in router_gws:
+            gw.create()
+
+        other = self._make_object({
+            'router_id': router_id,
+            'port_id': self._create_test_port_id(
+                device_owner=constants.DEVICE_OWNER_ROUTER_INTF),
+            'port_type': constants.DEVICE_OWNER_ROUTER_INTF,
+        })
+        other.create()
+
+        res_gws = self._test_class.get_gw_port_ids_by_router_id(self.context,
+                                                                router_id)
+        self.assertCountEqual(res_gws, [rp.port_id for rp in router_gws])
+
 
 class DVRMacAddressIfaceObjectTestCase(obj_test_base.BaseObjectIfaceTestCase):