Merge pull request #59747 from feiskyer/fix-59746

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Map correct vmset name for internal load balancers

**What this PR does / why we need it**:

When creating an internal loadbalancer, e.g.

```sh
cat << EOF | kubectl create -f -
apiVersion: v1
kind: Service
metadata:
  name: ingress-nginx
  annotations:
    service.beta.kubernetes.io/azure-load-balancer-internal: "true"
spec:
  type: LoadBalancer
  ports:
  - name: http
    port: 80
    targetPort: 80
    protocol: TCP
  - name: https
    port: 443
    targetPort: 443
    protocol: TCP
  selector:
    app: ingress-nginx
EOF
```

Then wait a while, and no target backends present for the internal load balancer even after 15 mins.

![](https://user-images.githubusercontent.com/10303889/36070528-54aa9848-0f22-11e8-834b-7401a2fa7611.png)

Refer https://github.com/Azure/acs-engine/issues/2151#issuecomment-364726846.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #59746

**Special notes for your reviewer**:

Should cherry pick to v1.9, v1.8, and v1.7 (and requires resolving conflicts manually).

**Release note**:

```release-note
Map correct vmset name for internal load balancers
```

pkg/cloudprovider/providers/azure/azure_standard.go

@@ -110,7 +110,7 @@ func (az *Cloud) getLoadBalancerProbeID(lbName, lbRuleName string) string {
 
 func (az *Cloud) mapLoadBalancerNameToVMSet(lbName string, clusterName string) (vmSetName string) {
 	vmSetName = strings.TrimSuffix(lbName, InternalLoadBalancerNameSuffix)
-	if strings.EqualFold(clusterName, lbName) {
+	if strings.EqualFold(clusterName, vmSetName) {
 		vmSetName = az.vmSet.GetPrimaryVMSetName()
 	}
 

pkg/cloudprovider/providers/azure/azure_standard_test.go

@@ -19,6 +19,8 @@ package azure
 import (
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+
 	"k8s.io/api/core/v1"
 	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
@@ -120,3 +122,45 @@ func TestGenerateStorageAccountName(t *testing.T) {
 		}
 	}
 }
+
+func TestMapLoadBalancerNameToVMSet(t *testing.T) {
+	az := getTestCloud()
+	az.PrimaryAvailabilitySetName = "primary"
+
+	cases := []struct {
+		description   string
+		lbName        string
+		clusterName   string
+		expectedVMSet string
+	}{
+		{
+			description:   "default external LB should map to primary vmset",
+			lbName:        "azure",
+			clusterName:   "azure",
+			expectedVMSet: "primary",
+		},
+		{
+			description:   "default internal LB should map to primary vmset",
+			lbName:        "azure-internal",
+			clusterName:   "azure",
+			expectedVMSet: "primary",
+		},
+		{
+			description:   "non-default external LB should map to its own vmset",
+			lbName:        "azuretest-internal",
+			clusterName:   "azure",
+			expectedVMSet: "azuretest",
+		},
+		{
+			description:   "non-default internal LB should map to its own vmset",
+			lbName:        "azuretest-internal",
+			clusterName:   "azure",
+			expectedVMSet: "azuretest",
+		},
+	}
+
+	for _, c := range cases {
+		vmset := az.mapLoadBalancerNameToVMSet(c.lbName, c.clusterName)
+		assert.Equal(t, c.expectedVMSet, vmset, c.description)
+	}
+}