Service Topology implementation

* Implement Service Topology for ipvs and iptables proxier
* Add test files
* API validation

pkg/proxy/iptables/proxier.go

@@ -181,6 +181,7 @@ type Proxier struct {
 	serviceMap   proxy.ServiceMap
 	endpointsMap proxy.EndpointsMap
 	portsMap     map[utilproxy.LocalPort]utilproxy.Closeable
+	nodeLabels   map[string]string
 	// endpointsSynced, endpointSlicesSynced, and servicesSynced are set to true
 	// when corresponding objects are synced after startup. This is used to avoid
 	// updating iptables with some partial data after kube-proxy restart.
@@ -591,6 +592,47 @@ func (proxier *Proxier) OnEndpointSlicesSynced() {
 	proxier.syncProxyRules()
 }
 
+// OnNodeAdd is called whenever creation of new node object
+// is observed.
+func (proxier *Proxier) OnNodeAdd(node *v1.Node) {
+	if node.Name != proxier.hostname {
+		klog.Errorf("Received a watch event for a node %s that doesn't match the current node %v", node.Name, proxier.hostname)
+		return
+	}
+	proxier.mu.Lock()
+	proxier.nodeLabels = node.Labels
+	proxier.mu.Unlock()
+}
+
+// OnNodeUpdate is called whenever modification of an existing
+// node object is observed.
+func (proxier *Proxier) OnNodeUpdate(oldNode, node *v1.Node) {
+	if node.Name != proxier.hostname {
+		klog.Errorf("Received a watch event for a node %s that doesn't match the current node %v", node.Name, proxier.hostname)
+		return
+	}
+	proxier.mu.Lock()
+	proxier.nodeLabels = node.Labels
+	proxier.mu.Unlock()
+}
+
+// OnNodeDelete is called whever deletion of an existing node
+// object is observed.
+func (proxier *Proxier) OnNodeDelete(node *v1.Node) {
+	if node.Name != proxier.hostname {
+		klog.Errorf("Received a watch event for a node %s that doesn't match the current node %v", node.Name, proxier.hostname)
+		return
+	}
+	proxier.mu.Lock()
+	proxier.nodeLabels = nil
+	proxier.mu.Unlock()
+}
+
+// OnNodeSynced is called once all the initial event handlers were
+// called and the state is fully propagated to local cache.
+func (proxier *Proxier) OnNodeSynced() {
+}
+
 // portProtoHash takes the ServicePortName and protocol for a service
 // returns the associated 16 character hash. This is computed by hashing (sha256)
 // then encoding to base32 and truncating to 16 chars. We do this because IPTables
@@ -858,7 +900,20 @@ func (proxier *Proxier) syncProxyRules() {
 		isIPv6 := utilnet.IsIPv6(svcInfo.ClusterIP())
 		protocol := strings.ToLower(string(svcInfo.Protocol()))
 		svcNameString := svcInfo.serviceNameString
-		hasEndpoints := len(proxier.endpointsMap[svcName]) > 0
+
+		allEndpoints := proxier.endpointsMap[svcName]
+
+		hasEndpoints := len(allEndpoints) > 0
+
+		// Service Topology will not be enabled in the following cases:
+		// 1. externalTrafficPolicy=Local (mutually exclusive with service topology).
+		// 2. ServiceTopology is not enabled.
+		// 3. EndpointSlice is not enabled (service topology depends on endpoint slice
+		// to get topology information).
+		if !svcInfo.OnlyNodeLocalEndpoints() && utilfeature.DefaultFeatureGate.Enabled(features.ServiceTopology) && utilfeature.DefaultFeatureGate.Enabled(features.EndpointSlice) {
+			allEndpoints = proxy.FilterTopologyEndpoint(proxier.nodeLabels, svcInfo.TopologyKeys(), allEndpoints)
+			hasEndpoints = len(allEndpoints) > 0
+		}
 
 		svcChain := svcInfo.servicePortChainName
 		if hasEndpoints {
@@ -1168,12 +1223,13 @@ func (proxier *Proxier) syncProxyRules() {
 		endpoints = endpoints[:0]
 		endpointChains = endpointChains[:0]
 		var endpointChain utiliptables.Chain
-		for _, ep := range proxier.endpointsMap[svcName] {
+		for _, ep := range allEndpoints {
 			epInfo, ok := ep.(*endpointsInfo)
 			if !ok {
 				klog.Errorf("Failed to cast endpointsInfo %q", ep.String())
 				continue
 			}
+
 			endpoints = append(endpoints, epInfo)
 			endpointChain = epInfo.endpointChain(svcNameString, protocol)
 			endpointChains = append(endpointChains, endpointChain)
@@ -1220,6 +1276,7 @@ func (proxier *Proxier) syncProxyRules() {
 				// Error parsing this endpoint has been logged. Skip to next endpoint.
 				continue
 			}
+
 			// Balancing rules in the per-service chain.
 			args = append(args[:0], "-A", string(svcChain))
 			proxier.appendServiceCommentLocked(args, svcNameString)