Merge pull request #3554 from k8s-infra-cherrypick-robot/cherry-pick-…

…3551-to-release-1.9

[release-1.9] allow setting the NatGateway name if it's empty when update AzureCluster

api/v1beta1/azurecluster_webhook.go

@@ -168,7 +168,7 @@ func (c *AzureCluster) validateSubnetUpdate(old *AzureCluster) field.ErrorList {
 						c.Spec.NetworkSpec.Subnets[i].RouteTable.Name, "field is immutable"),
 				)
 			}
-			if subnet.NatGateway.Name != oldSubnet.NatGateway.Name {
+			if (subnet.NatGateway.Name != oldSubnet.NatGateway.Name) && (oldSubnet.NatGateway.Name != "") {
 				allErrs = append(allErrs,
 					field.Invalid(field.NewPath("spec", "networkSpec", "subnets").Index(oldSubnetIndex[subnet.Name]).Child("NatGateway").Child("Name"),
 						c.Spec.NetworkSpec.Subnets[i].NatGateway.Name, "field is immutable"),

api/v1beta1/azurecluster_webhook_test.go

@@ -318,6 +318,30 @@ func TestAzureCluster_ValidateUpdate(t *testing.T) {
 			},
 			wantErr: true,
 		},
+		{
+			name: "natGateway name is immutable",
+			oldCluster: func() *AzureCluster {
+				cluster := createValidCluster()
+				cluster.Spec.NetworkSpec.Subnets[0].NatGateway.Name = "cluster-test-node-natgw-0"
+				return cluster
+			}(),
+			cluster: func() *AzureCluster {
+				cluster := createValidCluster()
+				cluster.Spec.NetworkSpec.Subnets[0].NatGateway.Name = "cluster-test-node-natgw-1"
+				return cluster
+			}(),
+			wantErr: true,
+		},
+		{
+			name:       "natGateway name can be empty before AzureCluster is updated",
+			oldCluster: createValidCluster(),
+			cluster: func() *AzureCluster {
+				cluster := createValidCluster()
+				cluster.Spec.NetworkSpec.Subnets[0].NatGateway.Name = "cluster-test-node-natgw"
+				return cluster
+			}(),
+			wantErr: false,
+		},
 	}
 	for _, tc := range tests {
 		tc := tc