test: Add tests for zone-redundant load balancers

- Add unit tests for zone configuration on frontend IPs
- Add E2E test for zone-redundant LB verification
- Add apiserver-ilb-zones flavor for E2E testing

Author: bryan-cox

azure/services/loadbalancers/loadbalancers_test.go

@@ -111,6 +111,30 @@ var (
 		APIServerPort: 6443,
 	}
 
+	fakeInternalAPILBSpecWithZones = LBSpec{
+		Name:                 "my-private-lb",
+		ResourceGroup:        "my-rg",
+		SubscriptionID:       "123",
+		ClusterName:          "my-cluster",
+		Location:             "my-location",
+		Role:                 infrav1.APIServerRole,
+		Type:                 infrav1.Internal,
+		SKU:                  infrav1.SKUStandard,
+		SubnetName:           "my-cp-subnet",
+		BackendPoolName:      "my-private-lb-backendPool",
+		IdleTimeoutInMinutes: ptr.To[int32](4),
+		AvailabilityZones:    []string{"1", "2", "3"},
+		FrontendIPConfigs: []infrav1.FrontendIP{
+			{
+				Name: "my-private-lb-frontEnd",
+				FrontendIPClass: infrav1.FrontendIPClass{
+					PrivateIPAddress: "10.0.0.10",
+				},
+			},
+		},
+		APIServerPort: 6443,
+	}
+
 	fakeNodeOutboundLBSpec = LBSpec{
 		Name:                 "my-cluster",
 		ResourceGroup:        "my-rg",

azure/services/loadbalancers/spec_test.go

@@ -178,6 +178,22 @@ func TestParameters(t *testing.T) {
 			},
 			expectedError: "",
 		},
+		{
+			name:     "internal load balancer with availability zones",
+			spec:     &fakeInternalAPILBSpecWithZones,
+			existing: nil,
+			expect: func(g *WithT, result interface{}) {
+				g.Expect(result).To(BeAssignableToTypeOf(armnetwork.LoadBalancer{}))
+				lb := result.(armnetwork.LoadBalancer)
+				// Verify zones are set on frontend IP configuration
+				g.Expect(lb.Properties.FrontendIPConfigurations).To(HaveLen(1))
+				g.Expect(lb.Properties.FrontendIPConfigurations[0].Zones).To(HaveLen(3))
+				g.Expect(*lb.Properties.FrontendIPConfigurations[0].Zones[0]).To(Equal("1"))
+				g.Expect(*lb.Properties.FrontendIPConfigurations[0].Zones[1]).To(Equal("2"))
+				g.Expect(*lb.Properties.FrontendIPConfigurations[0].Zones[2]).To(Equal("3"))
+			},
+			expectedError: "",
+		},
 	}
 	for _, tc := range testcases {
 		t.Run(tc.name, func(t *testing.T) {

templates/cluster-template-apiserver-ilb-zones.yaml

@@ -0,0 +1,11 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+namespace: default
+resources:
+- ../apiserver-ilb
+
+patches:
+- path: patches/lb-zones.yaml
+
+sortOptions:
+  order: fifo

templates/flavors/apiserver-ilb-zones/kustomization.yaml

@@ -0,0 +1,11 @@
+apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
+kind: AzureCluster
+metadata:
+  name: ${CLUSTER_NAME}
+spec:
+  networkSpec:
+    apiServerLB:
+      availabilityZones:
+        - "1"
+        - "2"
+        - "3"