Merge "Always Set dhcp_server in network_info"

nova/network/neutronv2/api.py

@@ -3103,6 +3103,23 @@ class API(base_api.NetworkAPI):
                         subnet_dict['dhcp_server'] = ip_pair['ip_address']
                         break
 
+            # NOTE(arnaudmorin): If enable_dhcp is set on subnet, but, for
+            # some reason neutron did not have any DHCP port yet, we still
+            # want the network_info to be populated with a valid dhcp_server
+            # value. This is mostly useful for the metadata API (which is
+            # relying on this value to give network_data to the instance).
+            #
+            # This will also help some providers which are using external
+            # DHCP servers not handled by neutron.
+            # In this case, neutron will never create any DHCP port in the
+            # subnet.
+            #
+            # Also note that we cannot set the value to None because then the
+            # value would be discarded by the metadata API.
+            # So the subnet gateway will be used as fallback.
+            if subnet.get('enable_dhcp') and 'dhcp_server' not in subnet_dict:
+                subnet_dict['dhcp_server'] = subnet['gateway_ip']
+
             subnet_object = network_model.Subnet(**subnet_dict)
             for dns in subnet.get('dns_nameservers', []):
                 subnet_object.add_dns(

nova/tests/unit/network/test_neutronv2.py

@@ -1954,6 +1954,49 @@ class TestNeutronv2(TestNeutronv2Base):
         self.assertEqual(subnet_data1[0]['host_routes'][0]['nexthop'],
                          subnets[0]['routes'][0]['gateway']['address'])
 
+    @mock.patch.object(neutronapi, 'get_client')
+    def test_get_subnets_from_port_enabled_dhcp(self, mock_get_client):
+        api = neutronapi.API()
+        mocked_client = mock.create_autospec(client.Client)
+        mock_get_client.return_value = mocked_client
+
+        port_data = copy.copy(self.port_data1[0])
+        # add another IP on the same subnet and verify the subnet is deduped
+        port_data['fixed_ips'].append({'ip_address': '10.0.1.3',
+                                       'subnet_id': 'my_subid1'})
+        subnet_data1 = copy.copy(self.subnet_data1)
+        subnet_data1[0]['enable_dhcp'] = True
+
+        mocked_client.list_subnets.return_value = {'subnets': subnet_data1}
+        mocked_client.list_ports.return_value = {'ports': self.dhcp_port_data1}
+
+        subnets = api._get_subnets_from_port(self.context, port_data)
+
+        self.assertEqual(self.dhcp_port_data1[0]['fixed_ips'][0]['ip_address'],
+                         subnets[0]['meta']['dhcp_server'])
+
+    @mock.patch.object(neutronapi, 'get_client')
+    def test_get_subnets_from_port_enabled_dhcp_no_dhcp_ports(self,
+            mock_get_client):
+        api = neutronapi.API()
+        mocked_client = mock.create_autospec(client.Client)
+        mock_get_client.return_value = mocked_client
+
+        port_data = copy.copy(self.port_data1[0])
+        # add another IP on the same subnet and verify the subnet is deduped
+        port_data['fixed_ips'].append({'ip_address': '10.0.1.3',
+                                       'subnet_id': 'my_subid1'})
+        subnet_data1 = copy.copy(self.subnet_data1)
+        subnet_data1[0]['enable_dhcp'] = True
+
+        mocked_client.list_subnets.return_value = {'subnets': subnet_data1}
+        mocked_client.list_ports.return_value = {'ports': []}
+
+        subnets = api._get_subnets_from_port(self.context, port_data)
+
+        self.assertEqual(subnet_data1[0]['gateway_ip'],
+                         subnets[0]['meta']['dhcp_server'])
+
     def test_get_all_empty_list_networks(self):
         api = neutronapi.API()
         neutronapi.get_client(mox.IgnoreArg()).AndReturn(self.moxed_client)

releasenotes/notes/always-set-dhcp-server-if-enable-dhcp-b96bf720af235902.yaml

@@ -0,0 +1,5 @@
+---
+features:
+  - When ``enable_dhcp`` is set on a subnet but there is no DHCP port on neutron
+    then the ``dhcp_server`` value in meta hash will contain the subnet
+    gateway IP instead of being absent.