Feature request: support for loadBalancerClass

[EmielBruijntjes]

Would it be possible to have the provider check the "loadBalancerClass", so that it only assigns IP addresses to matching services? For example by setting an environment variable "KUBEVIP_LB_CLASS" (or so).

[lubronzhan]

Yeah that sounds reasonable
Right now kube-vip supports this field

Kubernetes LoadBalancer Class (Kubernetes v1.24+) (kube-vip v0.5.0+)
The watcher will always examine the [load balancer class ](https://kubernetes.io/docs/concepts/services-networking/service/#load-balancer-class), and if it isn't set then will assume that classes aren't being set and act upon the service. If the spec.loadBalancerClass has been set in the service spec then kube-vip will only act IF the spec has been set to:

spec.loadBalancerClass=kube-vip.io/kube-vip-class.

And kube-vip loadbalancer should also honer it if they are used together

[lubronzhan]

Summarizing the functionality here

1. If service has loadbalancerClass, kube-vip-cloud-provider is not configured with loadbalancerClass, kube-vip-cloud-provider will ignore the service
2. If service doesn't have loadbalancerClass, kube-vip-cloud-provider is configured with loadbalancerClass, kube-vip-
   cloud-provider will ignore the service
3. If service has loadbalancerClass, kube-vip-cloud-provider is configured with loadbalancerClass, kube-vip-
   cloud-provider will allocate ip for the service
4. If service doesn't have loadbalancerClass, kube-vip-cloud-provider is not configured with loadbalancerClass, kube-vip-
   cloud-provider will allocate ip for the service

[lubronzhan]

Found problem with the implementation, since default cluod-provider won't reconcile service if it has loadbalancerClass set

https://github.com/kubernetes/cloud-provider/blob/982d74ad51fe6a37157eb20dd1386be1a2a0f106/controllers/service/controller.go#L824-L827

Need to come up with other way

[EmielBruijntjes]

@lubronzhan does this still have your attention, or can we better look for an alternative way to achieve this?

[lubronzhan]

Now it's supported