Fix delete pool lead to panic (#430)

1) seems we don't need port 22, have no idea why use here
2) when pool not exist, should check and ignore following actions

Author: jichenjc

pkg/cloud/openstack/machine/actuator.go

@@ -226,7 +226,7 @@ func (a *Actuator) Delete(ctx context.Context, cluster *clusterv1.Cluster, machi
 		return err
 	}
 	if clusterProviderSpec.ManagedAPIServerLoadBalancer {
-		err = loadbalancerService.DeleteLoadBalancerMember(clusterName, machine, clusterProviderStatus)
+		err = loadbalancerService.DeleteLoadBalancerMember(clusterName, machine, clusterProviderSpec, clusterProviderStatus)
 		if err != nil {
 			return err
 		}

pkg/cloud/openstack/services/loadbalancer/loadbalancer.go

@@ -264,7 +264,7 @@ func (s *Service) ReconcileLoadBalancerMember(clusterName string, machine *clust
 	return nil
 }
 
-func (s *Service) DeleteLoadBalancerMember(clusterName string, machine *clusterv1.Machine, clusterProviderStatus *providerv1.OpenstackClusterProviderStatus) error {
+func (s *Service) DeleteLoadBalancerMember(clusterName string, machine *clusterv1.Machine, clusterProviderSpec *providerv1.OpenstackClusterProviderSpec, clusterProviderStatus *providerv1.OpenstackClusterProviderStatus) error {
 
 	if machine == nil || !util.IsControlPlaneMachine(machine) {
 		return nil
@@ -275,14 +275,20 @@ func (s *Service) DeleteLoadBalancerMember(clusterName string, machine *clusterv
 
 	lbID := clusterProviderStatus.Network.APIServerLoadBalancer.ID
 
-	for _, port := range []int{22, 6443} {
+	portList := []int{clusterProviderSpec.APIServerLoadBalancerPort}
+	portList = append(portList, clusterProviderSpec.APIServerLoadBalancerAdditionalPorts...)
+	for _, port := range portList {
 		lbPortObjectsName := fmt.Sprintf("%s-%d", loadBalancerName, port)
 		name := lbPortObjectsName + "-" + machine.Name
 
 		pool, err := checkIfPoolExists(s.loadbalancerClient, lbPortObjectsName)
 		if err != nil {
 			return err
 		}
+		if pool == nil {
+			klog.Infof("Pool %s does not exist", lbPortObjectsName)
+			continue
+		}
 
 		lbMember, err := checkIfLbMemberExists(s.loadbalancerClient, pool.ID, name)
 		if err != nil {