Issue associating floating IP with OVN load balancer

[Will Szumski]

Version: yoga

I'm seeing this failure when trying to associate a floating IP to a OVN based loadbalancer:

    Maintenance task: Failed to fix resource 990f1d44-2401-49ba-b8c5-aedf7fb0c1ec (type: floatingips): TypeError: 'NoneType' object is not iterable
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance Traceback (most recent call last):
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/maintenance.py", line 400, in check_for_inconsistencies
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance self._fix_create_update(admin_context, row)
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/maintenance.py", line 239, in _fix_create_update
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance res_map['ovn_create'](context, n_obj)
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/maintenance.py", line 467, in _create_floatingip_and_pf
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance self._ovn_client.create_floatingip(context, floatingip)
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py", line 1201, in create_floatingip
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance LOG.error('Unable to create floating ip in gateway '
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/oslo_utils/excutils.py", line 227, in __exit__
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance self.force_reraise()
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/oslo_utils/excutils.py", line 200, in force_reraise
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance raise self.value
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py", line 1197, in create_floatingip
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance self._create_or_update_floatingip(floatingip, txn=txn)
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance File "/var/lib/kolla/venv/lib/python3.9/site-packages/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py", line 1007, in _create_or_update_floatingip
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance commands.extend(
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance TypeError: 'NoneType' object is not iterable
    2024-06-06 15:25:22.565 40 ERROR neutron.plugins.ml2.drivers.ovn.mech_driver.ovsdb.maintenance

Unsure if that is masking another issue, but seems like even in master _handle_lb_fip_cmds can return None e.g:

https://github.com/openstack/neutron/blob/11027e3e1ef9a58d5b2faa575a3764bd33cd2a08/neutron/plugins/ml2/drivers/ovn/mech_driver/ovsdb/ovn_client.py#L975

Unsure of the consqeuences of returning an empty list instead. Would that allow floating IP association to succeed?

[Brian Haley (brian-haley)]

I can only guess that line was supposed to be:

    if not ls_linked:
        continue

So that the next LB is tried. I don't think anything has changed in this code patch since it was committed.

If you could try that and see it would help as I don't remember seeing this before.

[Will Szumski (willjs)]

Thanks Brian. I can confirm that:

    if not ls_linked:
        continue

Fixed the issue for us. Makes total sense as there were several load balancers using this router.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/921663