fix load balancer IP change when updating service

pkg/cloudprovider/providers/azure/azure_loadbalancer.go

@@ -117,14 +117,6 @@ func (az *Cloud) EnsureLoadBalancer(ctx context.Context, clusterName string, ser
 	// Here we'll firstly ensure service do not lie in the opposite LB.
 	serviceName := getServiceName(service)
 	glog.V(5).Infof("ensureloadbalancer(%s): START clusterName=%q", serviceName, clusterName)
-	flippedService := flipServiceInternalAnnotation(service)
-	if _, err := az.reconcileLoadBalancer(clusterName, flippedService, nil, false /* wantLb */); err != nil {
-		return nil, err
-	}
-
-	if _, err := az.reconcilePublicIP(clusterName, service, true /* wantLb */); err != nil {
-		return nil, err
-	}
 
 	lb, err := az.reconcileLoadBalancer(clusterName, service, nodes, true /* wantLb */)
 	if err != nil {
@@ -145,6 +137,16 @@ func (az *Cloud) EnsureLoadBalancer(ctx context.Context, clusterName string, ser
 		return nil, err
 	}
 
+	updateService := updateServiceLoadBalancerIP(service, to.String(serviceIP))
+	flippedService := flipServiceInternalAnnotation(updateService)
+	if _, err := az.reconcileLoadBalancer(clusterName, flippedService, nil, false /* wantLb */); err != nil {
+		return nil, err
+	}
+
+	if _, err := az.reconcilePublicIP(clusterName, updateService, true /* wantLb */); err != nil {
+		return nil, err
+	}
+
 	return lbStatus, nil
 }
 
@@ -223,7 +225,7 @@ func (az *Cloud) getServiceLoadBalancer(service *v1.Service, clusterName string,
 				return nil, nil, false, err
 			}
 			if status == nil {
-				// service is not om this load balancer
+				// service is not on this load balancer
 				continue
 			}
 
@@ -409,6 +411,14 @@ func flipServiceInternalAnnotation(service *v1.Service) *v1.Service {
 	return copyService
 }
 
+func updateServiceLoadBalancerIP(service *v1.Service, serviceIP string) *v1.Service {
+	copyService := service.DeepCopy()
+	if len(serviceIP) > 0 && copyService != nil {
+		copyService.Spec.LoadBalancerIP = serviceIP
+	}
+	return copyService
+}
+
 func (az *Cloud) findServiceIPAddress(ctx context.Context, clusterName string, service *v1.Service, isInternalLb bool) (string, error) {
 	if len(service.Spec.LoadBalancerIP) > 0 {
 		return service.Spec.LoadBalancerIP, nil
@@ -502,6 +512,53 @@ func getIdleTimeout(s *v1.Service) (*int32, error) {
 	return &to32, nil
 }
 
+func (az *Cloud) isFrontendIPChanged(clusterName string, config network.FrontendIPConfiguration, service *v1.Service, lbFrontendIPConfigName string) (bool, error) {
+	if az.serviceOwnsFrontendIP(config, service) && !strings.EqualFold(to.String(config.Name), lbFrontendIPConfigName) {
+		return true, nil
+	}
+	if !strings.EqualFold(to.String(config.Name), lbFrontendIPConfigName) {
+		return false, nil
+	}
+	loadBalancerIP := service.Spec.LoadBalancerIP
+	isInternal := requiresInternalLoadBalancer(service)
+	if isInternal {
+		// Judge subnet
+		subnetName := subnet(service)
+		if subnetName != nil {
+			subnet, existsSubnet, err := az.getSubnet(az.VnetName, *subnetName)
+			if err != nil {
+				return false, err
+			}
+			if !existsSubnet {
+				return false, fmt.Errorf("failed to get subnet")
+			}
+			if config.Subnet != nil && !strings.EqualFold(to.String(config.Subnet.Name), to.String(subnet.Name)) {
+				return true, nil
+			}
+		}
+		if loadBalancerIP == "" {
+			return config.PrivateIPAllocationMethod == network.Static, nil
+		}
+		return config.PrivateIPAllocationMethod != network.Static || !strings.EqualFold(loadBalancerIP, to.String(config.PrivateIPAddress)), nil
+	}
+	if loadBalancerIP == "" {
+		return false, nil
+	}
+	pipName, err := az.determinePublicIPName(clusterName, service)
+	if err != nil {
+		return false, err
+	}
+	pipResourceGroup := az.getPublicIPAddressResourceGroup(service)
+	pip, existsPip, err := az.getPublicIPAddress(pipResourceGroup, pipName)
+	if err != nil {
+		return false, err
+	}
+	if !existsPip {
+		return true, nil
+	}
+	return config.PublicIPAddress != nil && !strings.EqualFold(to.String(pip.ID), to.String(config.PublicIPAddress.ID)), nil
+}
+
 // This ensures load balancer exists and the frontend ip config is setup.
 // This also reconciles the Service's Ports  with the LoadBalancer config.
 // This entails adding rules/probes for expected Ports and removing stale rules/ports.
@@ -574,16 +631,18 @@ func (az *Cloud) reconcileLoadBalancer(clusterName string, service *v1.Service,
 			}
 		}
 	} else {
-		if isInternal {
 		for i := len(newConfigs) - 1; i >= 0; i-- {
 			config := newConfigs[i]
-				if az.serviceOwnsFrontendIP(config, service) && !strings.EqualFold(*config.Name, lbFrontendIPConfigName) {
+			isFipChanged, err := az.isFrontendIPChanged(clusterName, config, service, lbFrontendIPConfigName)
+			if err != nil {
+				return nil, err
+			}
+			if isFipChanged {
 				glog.V(2).Infof("reconcileLoadBalancer for service (%s)(%t): lb frontendconfig(%s) - dropping", serviceName, wantLb, *config.Name)
 				newConfigs = append(newConfigs[:i], newConfigs[i+1:]...)
 				dirtyConfigs = true
 			}
 		}
-		}
 		foundConfig := false
 		for _, config := range newConfigs {
 			if strings.EqualFold(*config.Name, lbFrontendIPConfigName) {