Fix TopologyAwareHint not working when zone label is added after Node creation

The topology.kubernetes.io/zone label may be added by could provider
asynchronously after the Node is created. The previous code didn't
update the topology cache after receiving the Node update event, causing
TopologyAwareHint to not work until kube-controller-manager restarts or
other Node events trigger the update.

Signed-off-by: Quan Tian <qtian@vmware.com>

pkg/controller/endpointslice/endpointslice_controller.go

@@ -520,7 +520,10 @@ func (c *Controller) updateNode(old, cur interface{}) {
 	oldNode := old.(*v1.Node)
 	curNode := cur.(*v1.Node)
 
-	if topologycache.NodeReady(oldNode.Status) != topologycache.NodeReady(curNode.Status) {
+	// LabelTopologyZone may be added by cloud provider asynchronously after the Node is created.
+	// The topology cache should be updated in this case.
+	if topologycache.NodeReady(oldNode.Status) != topologycache.NodeReady(curNode.Status) ||
+		oldNode.Labels[v1.LabelTopologyZone] != curNode.Labels[v1.LabelTopologyZone] {
 		c.checkNodeTopologyDistribution()
 	}
 }

pkg/controller/endpointslice/endpointslice_controller_test.go

@@ -25,6 +25,7 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	v1 "k8s.io/api/core/v1"
 	discovery "k8s.io/api/discovery/v1"
 	"k8s.io/apimachinery/pkg/api/resource"
@@ -1877,6 +1878,80 @@ func Test_checkNodeTopologyDistribution(t *testing.T) {
 	}
 }
 
+func TestUpdateNode(t *testing.T) {
+	nodeReadyStatus := v1.NodeStatus{
+		Allocatable: map[v1.ResourceName]resource.Quantity{
+			v1.ResourceCPU: resource.MustParse("100m"),
+		},
+		Conditions: []v1.NodeCondition{
+			{
+				Type:   v1.NodeReady,
+				Status: v1.ConditionTrue,
+			},
+		},
+	}
+	_, esController := newController(nil, time.Duration(0))
+	sliceInfo := &topologycache.SliceInfo{
+		ServiceKey:  "ns/svc",
+		AddressType: discovery.AddressTypeIPv4,
+		ToCreate: []*discovery.EndpointSlice{
+			{
+				ObjectMeta: metav1.ObjectMeta{
+					Name:      "svc-abc",
+					Namespace: "ns",
+					Labels: map[string]string{
+						discovery.LabelServiceName: "svc",
+						discovery.LabelManagedBy:   controllerName,
+					},
+				},
+				Endpoints: []discovery.Endpoint{
+					{
+						Addresses:  []string{"172.18.0.2"},
+						Zone:       pointer.String("zone-a"),
+						Conditions: discovery.EndpointConditions{Ready: pointer.Bool(true)},
+					},
+					{
+						Addresses:  []string{"172.18.1.2"},
+						Zone:       pointer.String("zone-b"),
+						Conditions: discovery.EndpointConditions{Ready: pointer.Bool(true)},
+					},
+				},
+				AddressType: discovery.AddressTypeIPv4,
+			},
+		},
+	}
+	node1 := &v1.Node{
+		ObjectMeta: metav1.ObjectMeta{Name: "node-1"},
+		Status:     nodeReadyStatus,
+	}
+	node2 := &v1.Node{
+		ObjectMeta: metav1.ObjectMeta{Name: "node-2"},
+		Status:     nodeReadyStatus,
+	}
+	esController.nodeStore.Add(node1)
+	esController.nodeStore.Add(node2)
+	esController.addNode(node1)
+	esController.addNode(node2)
+	// The Nodes don't have the zone label, AddHints should fail.
+	_, _, eventsBuilders := esController.topologyCache.AddHints(sliceInfo)
+	require.Len(t, eventsBuilders, 1)
+	assert.Contains(t, eventsBuilders[0].Message, topologycache.InsufficientNodeInfo)
+
+	updateNode1 := node1.DeepCopy()
+	updateNode1.Labels = map[string]string{v1.LabelTopologyZone: "zone-a"}
+	updateNode2 := node2.DeepCopy()
+	updateNode2.Labels = map[string]string{v1.LabelTopologyZone: "zone-b"}
+
+	// After adding the zone label to the Nodes and calling the event handler updateNode, AddHints should succeed.
+	esController.nodeStore.Update(updateNode1)
+	esController.nodeStore.Update(updateNode2)
+	esController.updateNode(node1, updateNode1)
+	esController.updateNode(node2, updateNode2)
+	_, _, eventsBuilders = esController.topologyCache.AddHints(sliceInfo)
+	require.Len(t, eventsBuilders, 1)
+	assert.Contains(t, eventsBuilders[0].Message, topologycache.TopologyAwareHintsEnabled)
+}
+
 // Test helpers
 func addPods(t *testing.T, esController *endpointSliceController, namespace string, podsCount int) {
 	t.Helper()