dhcp agent start md-proxy with vrouter id only when has metadata subnet

When user create network with isolated subnet, dhcp agent will
create md-proxy with vrouter id. This will conflict with then md-proxy
created by l3 agent. This patch updated dhcp agent start md-proxy with
vrouter id only when the network has metadata subnet.

Change-Id: I3288327bf9d0cdf759a6fdf365d1289e8b7442db
Closes-Bug: #1703059

neutron/agent/dhcp/agent.py

@@ -505,8 +505,11 @@ class DhcpAgent(manager.Manager):
                                 {'port_num': len(router_ports),
                                  'port_id': router_ports[0].id,
                                  'router_id': router_ports[0].device_id})
-                kwargs = {'router_id': router_ports[0].device_id}
-                self._metadata_routers[network.id] = router_ports[0].device_id
+                all_subnets = self.dhcp_driver_cls._get_all_subnets(network)
+                if self.dhcp_driver_cls.has_metadata_subnet(all_subnets):
+                    kwargs = {'router_id': router_ports[0].device_id}
+                    self._metadata_routers[network.id] = (
+                        router_ports[0].device_id)
 
         metadata_driver.MetadataDriver.spawn_monitored_metadata_proxy(
             self._process_monitor, network.namespace, dhcp.METADATA_PORT,

neutron/agent/linux/dhcp.py

@@ -1067,6 +1067,15 @@ class Dnsmasq(DhcpLocalProcess):
 
         return isolated_subnets
 
+    @staticmethod
+    def has_metadata_subnet(subnets):
+        """Check if the subnets has a metadata subnet."""
+        meta_cidr = netaddr.IPNetwork(METADATA_DEFAULT_CIDR)
+        if any(netaddr.IPNetwork(s.cidr) in meta_cidr
+               for s in subnets):
+            return True
+        return False
+
     @classmethod
     def should_enable_metadata(cls, conf, network):
         """Determine whether the metadata proxy is needed for a network
@@ -1095,12 +1104,9 @@ class Dnsmasq(DhcpLocalProcess):
         if not conf.enable_isolated_metadata:
             return False
 
-        if conf.enable_metadata_network:
-            # check if the network has a metadata subnet
-            meta_cidr = netaddr.IPNetwork(METADATA_DEFAULT_CIDR)
-            if any(netaddr.IPNetwork(s.cidr) in meta_cidr
-                   for s in all_subnets):
-                return True
+        if (conf.enable_metadata_network and
+            cls.has_metadata_subnet(all_subnets)):
+            return True
 
         isolated_subnets = cls.get_isolated_subnets(network)
         return any(isolated_subnets[s.id] for s in v4_dhcp_subnets)

neutron/tests/unit/agent/linux/test_dhcp.py

@@ -2279,6 +2279,14 @@ class TestDnsmasq(TestBase):
         self.safe.assert_has_calls([mock.call(exp_host_name, exp_host_data),
                                     mock.call(exp_opt_name, exp_opt_data)])
 
+    def test_has_metadata_subnet_returns_true(self):
+        self.assertTrue(dhcp.Dnsmasq.has_metadata_subnet(
+            [FakeV4MetadataSubnet()]))
+
+    def test_has_metadata_subnet_returns_false(self):
+        self.assertFalse(dhcp.Dnsmasq.has_metadata_subnet(
+            [FakeV4Subnet()]))
+
     def test_should_enable_metadata_isolated_network_returns_true(self):
         self.assertTrue(dhcp.Dnsmasq.should_enable_metadata(
             self.conf, FakeV4NetworkNoRouter()))