[SRU] Loadbalacer stuck in status PENDING_DELETE if TLS storage unavailable in cascade deletion

[Impact]

Loadbalacer stuck in status PENDING_DELETE if TLS cert unavailable

[Test Case]

Pls refer to [Test steps] section below.

[Regression Potential]

The fix is already in the upstream main, stable/2024.1, stable/2023.2, stable/2023.1 branches, so it is a clean backport and might be helpful for deployments using octavia.

I also test this fix, it works well - https://paste.ubuntu.com/p/s4MsMjV6mP/

[Others]

Original Bug Description Below
===========

Loadbalacer stuck in status PENDING_DELETE if TLS cert unavailable

1. Create load balancer with TERMINATED_HTTPS listener
2. Disable your TLS storage, or delete cert from storage
3. Try to delete loadbalancer with cascade flag

Error on logs:

```
Unable to retrieve certificate(s) due to Could not retrieve certificate: <some id>
Exception during message handling
```

```
Traceback (most recent call last):
File "/var/lib/openstack/lib/python3.10/site-packages/oslo_messaging/rpc/server.py", line 165, in _process_incoming, res = self.dispatcher.dispatch(message),
File "/var/lib/openstack/lib/python3.10/site-packages/oslo_messaging/rpc/dispatcher.py", line 309, in dispatch, return self._do_dispatch(endpoint, method, ctxt, args),
File "/var/lib/openstack/lib/python3.10/site-packages/oslo_messaging/rpc/dispatcher.py", line 229, in _do_dispatch, result = func(ctxt, **new_args),
File "/var/lib/openstack/lib/python3.10/site-packages/octavia/controller/queue/v2/endpoints.py", line 56, in delete_load_balancer, self.worker.delete_load_balancer(loadbalancer, cascade),
File "/var/lib/openstack/lib/python3.10/site-packages/octavia/controller/worker/v2/controller_worker.py", line 387, in delete_load_balancer, listeners = flow_utils.get_listeners_on_lb(db_lb),
File "/var/lib/openstack/lib/python3.10/site-packages/octavia/controller/worker/v2/flows/flow_utils.py", line 52, in get_listeners_on_lb, prov_listener = provider_utils.db_listener_to_provider_listener(),
File "/var/lib/openstack/lib/python3.10/site-packages/octavia/api/drivers/utils.py", line 182, in db_listener_to_provider_listener, new_listener_dict = listener_dict_to_provider_dict(),
File "/var/lib/openstack/lib/python3.10/site-packages/octavia/api/drivers/utils.py", line 261, in listener_dict_to_provider_dict, with excutils.save_and_reraise_exception() as ctxt:,
File "/var/lib/openstack/lib/python3.10/site-packages/oslo_utils/excutils.py", line 227, in __exit__, self.force_reraise(),
File "/var/lib/openstack/lib/python3.10/site-packages/oslo_utils/excutils.py", line 200, in force_reraise, raise self.value,
File "/var/lib/openstack/lib/python3.10/site-packages/octavia/api/drivers/utils.py", line 258, in listener_dict_to_provider_dict, cert_dict = cert_parser.load_certificates_data(cert_manager)
File "/var/lib/openstack/lib/python3.10/site-packages/octavia/common/tls_utils/cert_parser.py", line 381, in load_certificates_data, raise exceptions.CertificateRetrievalException(, octavia.common.exceptions.CertificateRetrievalException: Could not retrieve certificate: ]

```

[Test steps]

1. Create load balancer with TERMINATED_HTTPS listener, eg:

secret1_id=$(openstack secret store --name='lb_tls_secret_1' -t 'application/octet-stream' -e 'base64' --payload="$(base64 < www.server1.com.p12)" -f value -c "Secret href")
octavia_user_id=$(openstack user show octavia --domain service_domain -f value -c id); echo $octavia_user_id;
openstack acl user add -u $octavia_user_id $secret1_id
subnetid=$(openstack subnet show private_subnet -f value -c id); echo $subnetid
lb_id=$(openstack loadbalancer create --name lb1 --vip-subnet-id $subnetid -f value -c id); echo $lb_id
listener_id=$(openstack loadbalancer listener create $lb_id --name https_listener --protocol-port 80 --protocol TERMINATED_HTTPS --default-tls-container=$secret1_id --sni-container-refs $secret1_id $secret2_id -f value -c id); echo $listener_id

2. Disable your TLS storage, or delete cert from storage, eg:

openstack secret delete $secret1_id

3. Try to delete loadbalancer with cascade flag

openstack loadbalancer delete lb1 --cascade

Here are the detailed steps for me to reproduce the problem - https://paste.ubuntu.com/p/wh3dJpJR9B/