host not removed from table ml2_vxlan_endpoints with the agent delete

[yatin]

After deleting an agent, there is stale entry for the host in table 'ml2_vxlan_endpoints'. An use case is during node scale down, a agent is deleted, but the host entry is not removed from ml2_vxlan_endpoints;

I have not checked other topologies but same should apply to other similar tables 'ml2_gre_endpoints' and 'ml2_geneve_endpoints'

# Ensure agent is stopped or node is removed.

$ openstack network agent show 338d13fc-3483-414f-bc55-5b2cbb0db189 --fit-width
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------+
| Field | Value |
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------+
| admin_state_up | UP |
| agent_type | Open vSwitch agent |
| alive | XXX |
| availability_zone | None |
| binary | neutron-openvswitch-agent |
| configuration | {'arp_responder_enabled': True, 'baremetal_smartnic': False, 'bridge_mappings': {'public': 'br-ex'}, 'datapath_type': 'system', |
| | 'devices': 0, 'enable_distributed_routing': True, 'extensions': [], 'in_distributed_mode': True, 'integration_bridge': 'br-int', |
| | 'l2_population': True, 'log_agent_heartbeats': False, 'ovs_capabilities': {'datapath_types': ['netdev', 'system'], 'iface_types': |
| | ['bareudp', 'erspan', 'geneve', 'gre', 'gtpu', 'internal', 'ip6erspan', 'ip6gre', 'lisp', 'patch', 'stt', 'system', 'tap', 'vxlan']}, |
| | 'ovs_hybrid_plug': False, 'resource_provider_bandwidths': {'br-ex': {'egress': 1000000, 'ingress': 1000000}}, |
| | 'resource_provider_hypervisors': {'br-ex': 'ykarel-temp3', 'rp_tunnelled': 'ykarel-temp3'}, 'resource_provider_inventory_defaults': |
| | {'allocation_ratio': 1.0, 'min_unit': 1, 'step_size': 1, 'reserved': 0}, 'resource_provider_packet_processing_inventory_defaults': |
| | {'allocation_ratio': 1.0, 'min_unit': 1, 'step_size': 1, 'reserved': 0}, 'resource_provider_packet_processing_with_direction': {}, |
| | 'resource_provider_packet_processing_without_direction': {}, 'tunnel_types': ['vxlan'], 'tunneling_ip': '10.0.109.173', |
| | 'vhostuser_socket_dir': '/var/run/openvswitch'} |
| created_at | 2023-10-25 14:30:17 |
| description | None |
| ha_state | None |
| host | ykarel-temp3 |
| id | 338d13fc-3483-414f-bc55-5b2cbb0db189 |
| last_heartbeat_at | 2023-10-25 14:30:17 |
| resources_synced | None |
| started_at | 2023-10-25 14:30:17 |
| topic | N/A |
+-------------------+----------------------------------------------------------------------------------------------------------------------------------------+

$ openstack network agent delete 338d13fc-3483-414f-bc55-5b2cbb0db189

mysql> select * from ml2_vxlan_endpoints;
+--------------+----------+--------------+
| ip_address | udp_port | host |
+--------------+----------+--------------+
| 10.0.109.173 | 4789 | ykarel-temp3 | <- Host/Ip entry still exist after the agent delete
| 10.0.109.224 | 4789 | ykarel-temp2 |
| 10.0.109.60 | 4789 | ykarel-temp1 |
+--------------+----------+--------------+
3 rows in set (0.00 sec)

The stale entry doesn't caused any issue but it's good to get rid of the host/node references which are removed from the cluster. Stale entries are also seen in table 'segmenthostmappings' which is the other known not fixed issue https://bugs.launchpad.net/neutron/+bug/1621717

These left overs were noticed in an older release train https://bugzilla.redhat.com/show_bug.cgi?id=2242298 but it still exists in master as seen above.

[Miro Tomaska (mtomaska)]

Also found this old bug[1] which should have fix this issue. But there were few refactors and the issue might have been reintroduced. I will look into it and I will see if there is a way to write a test to prevernt this from regressing again.

[1]https://bugs.launchpad.net/neutron/+bug/1179223

[Miro Tomaska (mtomaska)]

sorry I meant this change:
https://opendev.org/openstack/neutron/commit/3db0e619c83892a7aab61807969205253833ff8d?style=split&whitespace=show-all&show-outdated=#diff-fb2f785a0f554212d544b15abb18aea5e6e313e4