Repository: kubernetes-sigs/cloud-provider-azure (go)

Issue:
Should ignore the case of lb name when determing if the load balancer is an internal one
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#### What happened:

https://github.com/kubernetes-sigs/cloud-provider-azure/blob/7c0a8afb84df58905abe03583929f0f70ad48236/pkg/provider/azure_standard.go#L250

We should ignore the case of lb name when determing if the load balaner is an internal one.
For example: kubernetes-internal is an internal lb, KUBERNETES_INTERNAL is also an internal lb.

#### What you expected to happen:

#### How to reproduce it (as minimally and precisely as possible):

#### Anything else we need to know?:

#### Environment:

- Kubernetes version (use `kubectl version`):
- Cloud provider or hardware configuration:
- OS (e.g: `cat /etc/os-release`):
- Kernel (e.g. `uname -a`):
- Install tools:
- Network plugin and version (if this is a network-related bug):
- Others:


Pull request:
fix: The case of load balancer name should be ignored when determing …
…if it is an internal load balancer.

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/kind bug

#### What this PR does / why we need it:

fix: The case of load balancer name should be ignored when determing if it is an internal load balancer.

#### Which issue(s) this PR fixes:
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Fixes #5192

#### Special notes for your reviewer:

#### Does this PR introduce a user-facing change?
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```release-note
fix: The case of load balancer name should be ignored when determing if it is an internal load balancer.
```

#### Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

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```docs

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Patch:
diff --git a/pkg/provider/azure_standard.go b/pkg/provider/azure_standard.go
index 5cd445802..ca2a1bdae 100644
--- a/pkg/provider/azure_standard.go
+++ b/pkg/provider/azure_standard.go
@@ -246,10 +246,6 @@ func getIPConfigByIPFamily(nic network.Interface, IPv6 bool) (*network.Interface
 	return nil, fmt.Errorf("failed to determine the ipconfig(IPv6=%v). nicname=%q", IPv6, pointer.StringDeref(nic.Name, ""))
 }
 
-func isInternalLoadBalancer(lb *network.LoadBalancer) bool {
-	return strings.HasSuffix(*lb.Name, consts.InternalLoadBalancerNameSuffix)
-}
-
 // getBackendPoolName the LB BackendPool name for a service.
 // to ensure backward and forward compat:
 // SingleStack -v4 (pre v1.16) => BackendPool name == clusterName
diff --git a/pkg/provider/azure_utils.go b/pkg/provider/azure_utils.go
index bafcc4055..70ae36338 100644
--- a/pkg/provider/azure_utils.go
+++ b/pkg/provider/azure_utils.go
@@ -562,3 +562,7 @@ func getResourceGroupAndNameFromNICID(ipConfigurationID string) (string, string,
 	}
 	return nicResourceGroup, nicName, nil
 }
+
+func isInternalLoadBalancer(lb *network.LoadBalancer) bool {
+	return strings.HasSuffix(strings.ToLower(*lb.Name), consts.InternalLoadBalancerNameSuffix)
+}


Test patch:
diff --git a/kubetest2-aks/go.mod b/kubetest2-aks/go.mod
index b6ae03932..18253fcc3 100644
--- a/kubetest2-aks/go.mod
+++ b/kubetest2-aks/go.mod
@@ -1,6 +1,8 @@
 module sigs.k8s.io/cloud-provider-azure/kubetest2-aks
 
-go 1.18
+go 1.21
+
+toolchain go1.21.5
 
 require (
 	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.9.1
diff --git a/pkg/provider/azure_utils_test.go b/pkg/provider/azure_utils_test.go
index 2960b7c2b..78084fea1 100644
--- a/pkg/provider/azure_utils_test.go
+++ b/pkg/provider/azure_utils_test.go
@@ -895,3 +895,41 @@ func TestGetResourceIDPrefix(t *testing.T) {
 		})
 	}
 }
+
+func TestIsInternalLoadBalancer(t *testing.T) {
+	tests := []struct {
+		name     string
+		lb       network.LoadBalancer
+		expected bool
+	}{
+		{
+			name: "internal load balancer",
+			lb: network.LoadBalancer{
+				Name: pointer.String("test-internal"),
+			},
+			expected: true,
+		},
+		{
+			name: "internal load balancer",
+			lb: network.LoadBalancer{
+				Name: pointer.String("TEST-INTERNAL"),
+			},
+			expected: true,
+		},
+		{
+			name: "not internal load balancer",
+			lb: network.LoadBalancer{
+				Name: pointer.String("test"),
+			},
+			expected: false,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			lb := test.lb
+			result := isInternalLoadBalancer(&lb)
+			assert.Equal(t, test.expected, result)
+		})
+	}
+}