Cannot delete last LoadBalancer service when using VMO

[kon-angelo]

How to categorize this issue?

/area control-plane
/kind bug
/priority 3
/platform azure

What happened:

Deleting the last loadbalancer service will fail with error:

  Warning  SyncLoadBalancerFailed   3m27s (x11 over 6m35s)  service-controller               Error syncing load balancer: failed to delete load balancer: not a vmss instance

What you expected to happen:

For the service to be deleted

How to reproduce it (as minimally and precisely as possible):

1. Create a VMO cluster
2. Create a new service of type loadbalancer
3. Try to delete the service.

Be mindful, that if the shoot is not using the reverse VPN tunneling, then the "last" service will be the vpn-shoot service. In that case the skip step 2 and the_vpn-shoot_ service should be deleted

Anything else we need to know?:

The error seems to not be reproducible with the latest cloud-provider-azure version (v1.1.1). Solving #373 is a potential mitigation.

Environment:

• Gardener version (if relevant):
• Extension version: v1.21.x
• Kubernetes version (use kubectl version): 1.21.x
• Cloud provider or hardware configuration:
• Others:

[ialidzhikov]

I can confirm that this issue occurs. I checked that LoadBalancer creation and deletion works as expected with CCM v1.21.1. It seems that something changed in CCM v1.21.4 and it does no longer work for VMO clusters.

[ialidzhikov]

Ref kubernetes/kubernetes#105185 (credits to @kon-angelo)