[DHCP agent] Add route to OVN metadata port if exists

When DHCP agent is deployed with ml2/ovn for baremetal
ports, ovn metadata route is not added.

This patch adds route via ovn metadata port if exists
so baremetal nodes can fetch metadata.

Conflicts:
	neutron/agent/linux/dhcp.py

The conflict was just simple indent and formatting which needed
manual resolution

Closes-Bug: #1982569
Related-Bug: https://bugzilla.redhat.com/show_bug.cgi?id=2213862
Change-Id: I12e496d70bb6db707b317d0aeb6e4edd6c43571e
(cherry picked from commit 82f2a21)

Author: karelyatin

neutron/agent/linux/dhcp.py

@@ -1140,6 +1140,14 @@ def _output_opts_file(self):
         file_utils.replace_file(name, '\n'.join(options))
         return name
 
+    def _get_ovn_metadata_port_ip(self, subnet):
+        m_ports = [port for port in self.network.ports if
+                   self._is_ovn_metadata_port(port, self.network.id)]
+        if m_ports:
+            for fixed_ip in m_ports[0].fixed_ips:
+                if fixed_ip.subnet_id == subnet.id:
+                    return fixed_ip.ip_address
+
     def _generate_opts_per_subnet(self):
         options = []
         subnets_without_nameservers = set()
@@ -1193,23 +1201,33 @@ def _generate_opts_per_subnet(self):
                 else:
                     host_routes.append("%s,%s" % (hr.destination, hr.nexthop))
 
-            # Add host routes for isolated network segments
-
-            if ((self.conf.force_metadata or
-                 (isolated_subnets[subnet.id] and
-                     self.conf.enable_isolated_metadata)) and
-                    subnet.ip_version == 4):
-                subnet_dhcp_ip = subnet_to_interface_ip.get(subnet.id)
-                if subnet_dhcp_ip:
+            # Determine metadata port route
+            if subnet.ip_version == constants.IP_VERSION_4:
+                metadata_route_ip = None
+                # NOTE: OVN metadata port IP is used in a case when the DHCP
+                # agent is deployed in the ML2/OVN enviroment where the native
+                # ovn-controller dhcp is disabled. The ovn metadata route
+                # takes precedence over native force_metadata and
+                # enable_isolated_metadata routes settings.
+                ovn_metadata_port_ip = self._get_ovn_metadata_port_ip(subnet)
+                if ovn_metadata_port_ip:
+                    metadata_route_ip = ovn_metadata_port_ip
+
+                elif (self.conf.force_metadata or
+                        (isolated_subnets[subnet.id] and
+                        self.conf.enable_isolated_metadata)):
+                    subnet_dhcp_ip = subnet_to_interface_ip.get(subnet.id)
+                    if subnet_dhcp_ip:
+                        metadata_route_ip = subnet_dhcp_ip
+
+                if not isolated_subnets[subnet.id] and gateway:
+                    metadata_route_ip = gateway
+
+                if metadata_route_ip:
                     host_routes.append(
-                        '%s,%s' % (constants.METADATA_CIDR, subnet_dhcp_ip)
+                        '%s,%s' % (constants.METADATA_CIDR, metadata_route_ip)
                     )
-            elif not isolated_subnets[subnet.id] and gateway:
-                host_routes.append(
-                    '%s,%s' % (constants.METADATA_CIDR, gateway)
-                )
 
-            if subnet.ip_version == 4:
                 for s in self._get_all_subnets(self.network):
                     sub_segment_id = getattr(s, 'segment_id', None)
                     if (s.ip_version == 4 and
@@ -1374,13 +1392,21 @@ def has_metadata_subnet(subnets):
             return True
         return False
 
+    @staticmethod
+    def _is_ovn_metadata_port(port, network_id):
+        return (port.device_id == 'ovnmeta-' + network_id and
+                port.device_owner == constants.DEVICE_OWNER_DISTRIBUTED)
+
     @classmethod
     def should_enable_metadata(cls, conf, network):
         """Determine whether the metadata proxy is needed for a network
 
-        This method returns True for truly isolated networks (ie: not attached
-        to a router) when enable_isolated_metadata is True, or for all the
-        networks when the force_metadata flags is True.
+        If the given network contains a ovn metadata port then this method
+        assumes that the ovn metadata service is in use and this metadata
+        service is not required, method returns False. For other cases this
+        method returns True for truly isolated networks (ie: not attached to a
+        router) when enable_isolated_metadata is True, or for all the networks
+        when the force_metadata flags is True.
 
         This method also returns True when enable_metadata_network is True,
         and the network passed as a parameter has a subnet in the link-local
@@ -1389,6 +1415,10 @@ def should_enable_metadata(cls, conf, network):
         providing access to the metadata service via logical routers built
         with 3rd party backends.
         """
+        for port in network.ports:
+            if cls._is_ovn_metadata_port(port, network.id):
+                return False
+
         all_subnets = cls._get_all_subnets(network)
         dhcp_subnets = [s for s in all_subnets if s.enable_dhcp]
         if not dhcp_subnets:

neutron/tests/unit/agent/dhcp/test_agent.py

@@ -152,10 +152,27 @@
 
 fake_ipv6_port = dhcp.DictModel(id='12345678-1234-aaaa-123456789000',
                                 device_owner='',
+                                device_id='',
                                 mac_address='aa:bb:cc:dd:ee:99',
                                 network_id=FAKE_NETWORK_UUID,
                                 fixed_ips=[fake_fixed_ipv6])
 
+fake_ovn_port = dhcp.DictModel(id='12345678-1234-aaaa-123456789000',
+                               device_owner='',
+                               device_id='',
+                               mac_address='aa:bb:cc:dd:ee:98',
+                               network_id=FAKE_NETWORK_UUID,
+                               fixed_ips=[fake_fixed_ip2])
+
+fake_ovn_metadata_port = dhcp.DictModel(id='12345678-1234-aaaa-123456789000',
+                                        device_owner=const.
+                                        DEVICE_OWNER_DISTRIBUTED,
+                                        device_id='ovnmeta-{}'.format(
+                                            FAKE_NETWORK_UUID),
+                                        mac_address='aa:bb:cc:dd:ee:99',
+                                        network_id=FAKE_NETWORK_UUID,
+                                        fixed_ips=[fake_fixed_ip1])
+
 fake_meta_port = dhcp.DictModel(id='12345678-1234-aaaa-1234567890ab',
                                 mac_address='aa:bb:cc:dd:ee:ff',
                                 network_id=FAKE_NETWORK_UUID,
@@ -191,6 +208,12 @@
                                   subnets=[fake_ipv6_subnet],
                                   ports=[fake_ipv6_port])
 
+fake_ovn_network = dhcp.NetModel(id=FAKE_NETWORK_UUID,
+                                 project_id=FAKE_PROJECT_ID,
+                                 admin_state_up=True,
+                                 subnets=[fake_ipv6_subnet],
+                                 ports=[fake_ovn_metadata_port, fake_ovn_port])
+
 fake_network_ipv6_ipv4 = dhcp.NetModel(
     id=FAKE_NETWORK_UUID,
     project_id=FAKE_PROJECT_ID,
@@ -782,7 +805,7 @@ def _process_manager_constructor_call(self, ns=FAKE_NETWORK_DHCP_NS):
                          default_cmd_callback=mock.ANY)
 
     def _enable_dhcp_helper(self, network, enable_isolated_metadata=False,
-                            is_isolated_network=False):
+                            is_isolated_network=False, is_ovn_network=False):
         self.dhcp._process_monitor = mock.Mock()
         if enable_isolated_metadata:
             cfg.CONF.set_override('enable_isolated_metadata', True)
@@ -792,7 +815,8 @@ def _enable_dhcp_helper(self, network, enable_isolated_metadata=False,
             mock.call.get_network_info(network.id)])
         self.call_driver.assert_called_once_with('enable', network)
         self.cache.assert_has_calls([mock.call.put(network)])
-        if is_isolated_network and enable_isolated_metadata:
+        if (is_isolated_network and enable_isolated_metadata and not
+                is_ovn_network):
             self.external_process.assert_has_calls([
                 self._process_manager_constructor_call(),
                 mock.call().enable()], any_order=True)
@@ -837,6 +861,21 @@ def test_enable_dhcp_helper_enable_metadata_nonisolated_dist_network(self):
                                  enable_isolated_metadata=True,
                                  is_isolated_network=False)
 
+    def test_enable_dhcp_helper_enable_metadata_ovn_network(self):
+        # Metadata should not be enabled when the dhcp agent is used
+        # in ML2/OVN where the ovn metadata agent is responsible for the
+        # metadata service.
+        self._enable_dhcp_helper(fake_ovn_network, is_ovn_network=True)
+
+    def test_enable_dhcp_helper_ovn_network_with_enable_isolated_metadata(
+            self):
+        # Metadata should not be enabled when the dhcp agent is used
+        # in ML2/OVN where the ovn metadata agent is responsible for the
+        # metadata service. Even if the enable_isolated_metadata is enabled
+        self._enable_dhcp_helper(fake_ovn_network,
+                                 enable_isolated_metadata=True,
+                                 is_ovn_network=True)
+
     def test_enable_dhcp_helper_enable_metadata_empty_network(self):
         self._enable_dhcp_helper(empty_network,
                                  enable_isolated_metadata=True,

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

@@ -88,6 +88,19 @@ def __init__(self):
         self.extra_dhcp_opts = []
 
 
+class FakeOvnMetadataPort(object):
+    def __init__(self):
+        self.id = 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaa'
+        self.admin_state_up = True
+        self.device_owner = constants.DEVICE_OWNER_DISTRIBUTED
+        self.fixed_ips = [
+            FakeIPAllocation('192.168.0.10',
+                             'dddddddd-dddd-dddd-dddd-dddddddddddd')]
+        self.mac_address = '00:00:80:aa:bb:ee'
+        self.device_id = 'ovnmeta-aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa'
+        self.extra_dhcp_opts = []
+
+
 class FakeReservedPort(object):
     def __init__(self, id='reserved-aaaa-aaaa-aaaa-aaaaaaaaaaa'):
         self.admin_state_up = True
@@ -755,6 +768,14 @@ def __init__(self):
         self.namespace = 'qdhcp-ns'
 
 
+class FakeNetworkDhcpandOvnMetadataPort(object):
+    def __init__(self):
+        self.id = 'aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa'
+        self.subnets = [FakeV4Subnet()]
+        self.ports = [FakePort1(), FakeDhcpPort(), FakeOvnMetadataPort()]
+        self.namespace = 'qdhcp-ns'
+
+
 class FakeDualNetworkGatewayRoute(object):
     def __init__(self):
         self.id = 'cccccccc-cccc-cccc-cccc-cccccccccccc'
@@ -3050,6 +3071,10 @@ def test_has_metadata_subnet_returns_false(self):
         self.assertFalse(dhcp.Dnsmasq.has_metadata_subnet(
             [FakeV4Subnet()]))
 
+    def test_should_enable_metadata_ovn_metadata_port_returns_false(self):
+        self.assertFalse(dhcp.Dnsmasq.should_enable_metadata(
+            self.conf, FakeNetworkDhcpandOvnMetadataPort()))
+
     def test_should_enable_metadata_isolated_network_returns_true(self):
         self.assertTrue(dhcp.Dnsmasq.should_enable_metadata(
             self.conf, FakeV4NetworkNoRouter()))
@@ -3098,6 +3123,12 @@ def test__generate_opts_per_subnet_no_metadata(self):
                   'force_metadata': False}
         self._test__generate_opts_per_subnet_helper(config, False)
 
+    def test__generate_opts_per_subnet_with_metadata_port(self):
+        config = {'enable_isolated_metadata': False,
+                  'force_metadata': False}
+        self._test__generate_opts_per_subnet_helper(config, True,
+            network_class=FakeNetworkDhcpandOvnMetadataPort)
+
     def test__generate_opts_per_subnet_isolated_metadata_with_router(self):
         config = {'enable_isolated_metadata': True,
                   'force_metadata': False}

releasenotes/notes/dhcp-agent-ovn-metadata-port-33a654ccb9554c65.yaml

@@ -0,0 +1,9 @@
+---
+fixes:
+  - |
+    Fixed the scenario where the DHCP agent is deployed in conjunction with
+    the OVN metadata agent in order to serve metadata for baremetal nodes.
+    In this scenario, the DHCP agent would not set the route needed for the
+    OVN metadata agent service resulting in baremetal nodes not being able
+    to query the metadata service. For more information see
+    `bug 1982569 <https://bugs.launchpad.net/neutron/+bug/1982569>`_.