Add support for backend protocol selection in HTTP and GRPC routes

integration/k8s_conformance_test.go

@@ -213,6 +213,8 @@ func (s *K8sConformanceSuite) TestK8sGatewayAPIConformance() {
 			features.SupportHTTPRoutePathRedirect,
 			features.SupportHTTPRouteResponseHeaderModification,
 			features.SupportTLSRoute,
+			features.SupportHTTPRouteBackendProtocolH2C,
+			features.SupportHTTPRouteBackendProtocolWebSocket,
 		),
 	})
 	require.NoError(s.T(), err)

pkg/provider/kubernetes/gateway/fixtures/httproute/with_app_protocol_service.yml

@@ -0,0 +1,61 @@
+---
+kind: GatewayClass
+apiVersion: gateway.networking.k8s.io/v1
+metadata:
+  name: my-gateway-class
+spec:
+  controllerName: traefik.io/gateway-controller
+
+---
+kind: Gateway
+apiVersion: gateway.networking.k8s.io/v1
+metadata:
+  name: my-gateway
+  namespace: default
+spec:
+  gatewayClassName: my-gateway-class
+  listeners: # Use GatewayClass defaults for listener definition.
+    - name: http
+      protocol: HTTP
+      port: 80
+      allowedRoutes:
+        kinds:
+          - kind: HTTPRoute
+            group: gateway.networking.k8s.io
+        namespaces:
+          from: Same
+
+---
+kind: HTTPRoute
+apiVersion: gateway.networking.k8s.io/v1
+metadata:
+  name: http-multi-protocols
+  namespace: default
+spec:
+  parentRefs:
+    - name: my-gateway
+      kind: Gateway
+      group: gateway.networking.k8s.io
+  hostnames:
+    - "foo.com"
+  rules:
+    - matches:
+        - path:
+            type: Exact
+            value: /bar
+      backendRefs:
+        - name: whoami-h2c
+          port: 80
+          weight: 1
+          kind: Service
+          group: ""
+        - name: whoami-ws
+          port: 80
+          weight: 1
+          kind: Service
+          group: ""
+        - name: whoami-wss
+          port: 80
+          weight: 1
+          kind: Service
+          group: ""

pkg/provider/kubernetes/gateway/fixtures/services.yml

@@ -7,9 +7,11 @@ metadata:
 spec:
   ports:
     - name: web2
+      protocol: TCP
       port: 8000
       targetPort: web2
     - name: web
+      protocol: TCP
       port: 80
       targetPort: web
   selector:
@@ -48,9 +50,11 @@ metadata:
 spec:
   ports:
     - name: web2
+      protocol: TCP
       port: 8000
       targetPort: web2
     - name: web
+      protocol: TCP
       port: 80
       targetPort: web
   selector:
@@ -89,6 +93,7 @@ metadata:
 spec:
   ports:
     - name: web
+      protocol: TCP
       port: 8080
       targetPort: web
   selector:
@@ -317,3 +322,105 @@ status:
     ingress:
       - hostname: foo.bar
       - ip: 1.2.3.4
+
+---
+kind: EndpointSlice
+apiVersion: discovery.k8s.io/v1
+metadata:
+  name: whoami-h2c
+  namespace: default
+  labels:
+    kubernetes.io/service-name: whoami-h2c
+
+addressType: IPv4
+ports:
+  - name: h2c
+    protocol: TCP
+    port: 80
+endpoints:
+  - addresses:
+      - 10.10.0.13
+    conditions:
+      ready: true
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: whoami-h2c
+  namespace: default
+
+spec:
+  ports:
+    - protocol: TCP
+      port: 80
+      name: h2c
+      appProtocol: kubernetes.io/h2c
+
+---
+kind: EndpointSlice
+apiVersion: discovery.k8s.io/v1
+metadata:
+  name: whoami-ws
+  namespace: default
+  labels:
+    kubernetes.io/service-name: whoami-ws
+
+addressType: IPv4
+ports:
+  - name: ws
+    protocol: TCP
+    port: 80
+endpoints:
+  - addresses:
+      - 10.10.0.14
+    conditions:
+      ready: true
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: whoami-ws
+  namespace: default
+
+spec:
+  ports:
+    - protocol: TCP
+      port: 80
+      name: ws
+      appProtocol: kubernetes.io/ws
+
+---
+kind: EndpointSlice
+apiVersion: discovery.k8s.io/v1
+metadata:
+  name: whoami-wss
+  namespace: default
+  labels:
+    kubernetes.io/service-name: whoami-wss
+
+addressType: IPv4
+ports:
+  - name: wss
+    protocol: TCP
+    port: 80
+endpoints:
+  - addresses:
+      - 10.10.0.15
+    conditions:
+      ready: true
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: whoami-wss
+  namespace: default
+
+spec:
+  ports:
+    - protocol: TCP
+      port: 80
+      name: wss
+      appProtocol: kubernetes.io/wss

pkg/provider/kubernetes/gateway/grpcroute.go

@@ -2,7 +2,6 @@ package gateway
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net"
 	"strconv"
@@ -260,23 +259,16 @@ func (p *Provider) loadGRPCBackendRef(route *gatev1.GRPCRoute, backendRef gatev1
 			ObservedGeneration: route.Generation,
 			LastTransitionTime: metav1.Now(),
 			Reason:             string(gatev1.RouteReasonUnsupportedProtocol),
-			Message:            fmt.Sprintf("Cannot load GRPCBackendRef %s/%s/%s/%s port is required", group, kind, namespace, backendRef.Name),
+			Message:            fmt.Sprintf("Cannot load GRPCBackendRef %s/%s/%s/%s: port is required", group, kind, namespace, backendRef.Name),
 		}
 	}
 
 	portStr := strconv.FormatInt(int64(port), 10)
 	serviceName = provider.Normalize(serviceName + "-" + portStr)
 
-	lb, err := p.loadGRPCServers(namespace, backendRef)
-	if err != nil {
-		return serviceName, nil, &metav1.Condition{
-			Type:               string(gatev1.RouteConditionResolvedRefs),
-			Status:             metav1.ConditionFalse,
-			ObservedGeneration: route.Generation,
-			LastTransitionTime: metav1.Now(),
-			Reason:             string(gatev1.RouteReasonBackendNotFound),
-			Message:            fmt.Sprintf("Cannot load GRPCBackendRef %s/%s/%s/%s: %s", group, kind, namespace, backendRef.Name, err),
-		}
+	lb, errCondition := p.loadGRPCServers(namespace, route, backendRef)
+	if errCondition != nil {
+		return serviceName, nil, errCondition
 	}
 
 	return serviceName, &dynamic.Service{LoadBalancer: lb}, nil
@@ -319,72 +311,49 @@ func (p *Provider) loadGRPCMiddlewares(conf *dynamic.Configuration, namespace, r
 	return middlewareNames, nil
 }
 
-func (p *Provider) loadGRPCServers(namespace string, backendRef gatev1.GRPCBackendRef) (*dynamic.ServersLoadBalancer, error) {
-	if backendRef.Port == nil {
-		return nil, errors.New("port is required for Kubernetes Service reference")
-	}
-
-	service, exists, err := p.client.GetService(namespace, string(backendRef.Name))
+func (p *Provider) loadGRPCServers(namespace string, route *gatev1.GRPCRoute, backendRef gatev1.GRPCBackendRef) (*dynamic.ServersLoadBalancer, *metav1.Condition) {
+	backendAddresses, svcPort, err := p.getBackendAddresses(namespace, backendRef.BackendRef)
 	if err != nil {
-		return nil, fmt.Errorf("getting service: %w", err)
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.Generation,
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonBackendNotFound),
+			Message:            fmt.Sprintf("Cannot load GRPCBackendRef %s/%s: %s", namespace, backendRef.Name, err),
 		}
-	if !exists {
-		return nil, errors.New("service not found")
 	}
 
-	var svcPort *corev1.ServicePort
-	for _, p := range service.Spec.Ports {
-		if p.Port == int32(*backendRef.Port) {
-			svcPort = &p
-			break
+	if svcPort.Protocol != corev1.ProtocolTCP {
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.Generation,
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonUnsupportedProtocol),
+			Message:            fmt.Sprintf("Cannot load GRPCBackendRef %s/%s: only TCP protocol is supported", namespace, backendRef.Name),
 		}
 	}
-	if svcPort == nil {
-		return nil, fmt.Errorf("service port %d not found", *backendRef.Port)
-	}
 
-	endpointSlices, err := p.client.ListEndpointSlicesForService(namespace, string(backendRef.Name))
-	if err != nil {
-		return nil, fmt.Errorf("getting endpointslices: %w", err)
+	if svcPort.AppProtocol != nil && *svcPort.AppProtocol != appProtocolH2C {
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.Generation,
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonUnsupportedProtocol),
+			Message:            fmt.Sprintf("Cannot load GRPCBackendRef %s/%s: only kubernetes.io/h2c appProtocol is supported", namespace, backendRef.Name),
 		}
-	if len(endpointSlices) == 0 {
-		return nil, errors.New("endpointslices not found")
 	}
 
 	lb := &dynamic.ServersLoadBalancer{}
 	lb.SetDefaults()
 
-	addresses := map[string]struct{}{}
-	for _, endpointSlice := range endpointSlices {
-		var port int32
-		for _, p := range endpointSlice.Ports {
-			if svcPort.Name == *p.Name {
-				port = *p.Port
-				break
-			}
-		}
-		if port == 0 {
-			continue
-		}
-
-		for _, endpoint := range endpointSlice.Endpoints {
-			if endpoint.Conditions.Ready == nil || !*endpoint.Conditions.Ready {
-				continue
-			}
-
-			for _, address := range endpoint.Addresses {
-				if _, ok := addresses[address]; ok {
-					continue
-				}
-
-				addresses[address] = struct{}{}
+	for _, ba := range backendAddresses {
 		lb.Servers = append(lb.Servers, dynamic.Server{
-					URL: fmt.Sprintf("h2c://%s", net.JoinHostPort(address, strconv.Itoa(int(port)))),
+			URL: fmt.Sprintf("h2c://%s", net.JoinHostPort(ba.Address, strconv.Itoa(int(ba.Port)))),
 		})
 	}
-		}
-	}
-
 	return lb, nil
 }
 

pkg/provider/kubernetes/gateway/httproute.go

@@ -260,23 +260,16 @@ func (p *Provider) loadService(route *gatev1.HTTPRoute, backendRef gatev1.HTTPBa
 			ObservedGeneration: route.Generation,
 			LastTransitionTime: metav1.Now(),
 			Reason:             string(gatev1.RouteReasonUnsupportedProtocol),
-			Message:            fmt.Sprintf("Cannot load HTTPBackendRef %s/%s/%s/%s port is required", group, kind, namespace, backendRef.Name),
+			Message:            fmt.Sprintf("Cannot load HTTPBackendRef %s/%s/%s/%s: port is required", group, kind, namespace, backendRef.Name),
 		}
 	}
 
 	portStr := strconv.FormatInt(int64(port), 10)
 	serviceName = provider.Normalize(serviceName + "-" + portStr)
 
-	lb, err := p.loadHTTPServers(namespace, backendRef)
-	if err != nil {
-		return serviceName, nil, &metav1.Condition{
-			Type:               string(gatev1.RouteConditionResolvedRefs),
-			Status:             metav1.ConditionFalse,
-			ObservedGeneration: route.Generation,
-			LastTransitionTime: metav1.Now(),
-			Reason:             string(gatev1.RouteReasonBackendNotFound),
-			Message:            fmt.Sprintf("Cannot load HTTPBackendRef %s/%s/%s/%s: %s", group, kind, namespace, backendRef.Name, err),
-		}
+	lb, errCondition := p.loadHTTPServers(namespace, route, backendRef)
+	if errCondition != nil {
+		return serviceName, nil, errCondition
 	}
 
 	return serviceName, &dynamic.Service{LoadBalancer: lb}, nil
@@ -372,74 +365,39 @@ func (p *Provider) loadHTTPRouteFilterExtensionRef(namespace string, extensionRe
 	return filterFunc(string(extensionRef.Name), namespace)
 }
 
-func (p *Provider) loadHTTPServers(namespace string, backendRef gatev1.HTTPBackendRef) (*dynamic.ServersLoadBalancer, error) {
-	if backendRef.Port == nil {
-		return nil, errors.New("port is required for Kubernetes Service reference")
-	}
-
-	service, exists, err := p.client.GetService(namespace, string(backendRef.Name))
+func (p *Provider) loadHTTPServers(namespace string, route *gatev1.HTTPRoute, backendRef gatev1.HTTPBackendRef) (*dynamic.ServersLoadBalancer, *metav1.Condition) {
+	backendAddresses, svcPort, err := p.getBackendAddresses(namespace, backendRef.BackendRef)
 	if err != nil {
-		return nil, fmt.Errorf("getting service: %w", err)
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.Generation,
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonBackendNotFound),
+			Message:            fmt.Sprintf("Cannot load HTTPBackendRef %s/%s: %s", namespace, backendRef.Name, err),
 		}
-	if !exists {
-		return nil, errors.New("service not found")
 	}
 
-	var svcPort *corev1.ServicePort
-	for _, p := range service.Spec.Ports {
-		if p.Port == int32(*backendRef.Port) {
-			svcPort = &p
-			break
-		}
-	}
-	if svcPort == nil {
-		return nil, fmt.Errorf("service port %d not found", *backendRef.Port)
-	}
-
-	endpointSlices, err := p.client.ListEndpointSlicesForService(namespace, string(backendRef.Name))
+	protocol, err := getProtocol(svcPort)
 	if err != nil {
-		return nil, fmt.Errorf("getting endpointslices: %w", err)
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.Generation,
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonUnsupportedProtocol),
+			Message:            fmt.Sprintf("Cannot load HTTPBackendRef %s/%s: %s", namespace, backendRef.Name, err),
 		}
-	if len(endpointSlices) == 0 {
-		return nil, errors.New("endpointslices not found")
 	}
 
 	lb := &dynamic.ServersLoadBalancer{}
 	lb.SetDefaults()
 
-	protocol := getProtocol(*svcPort)
-
-	addresses := map[string]struct{}{}
-	for _, endpointSlice := range endpointSlices {
-		var port int32
-		for _, p := range endpointSlice.Ports {
-			if svcPort.Name == *p.Name {
-				port = *p.Port
-				break
-			}
-		}
-		if port == 0 {
-			continue
-		}
-
-		for _, endpoint := range endpointSlice.Endpoints {
-			if endpoint.Conditions.Ready == nil || !*endpoint.Conditions.Ready {
-				continue
-			}
-
-			for _, address := range endpoint.Addresses {
-				if _, ok := addresses[address]; ok {
-					continue
-				}
-
-				addresses[address] = struct{}{}
+	for _, ba := range backendAddresses {
 		lb.Servers = append(lb.Servers, dynamic.Server{
-					URL: fmt.Sprintf("%s://%s", protocol, net.JoinHostPort(address, strconv.Itoa(int(port)))),
+			URL: fmt.Sprintf("%s://%s", protocol, net.JoinHostPort(ba.Address, strconv.Itoa(int(ba.Port)))),
 		})
 	}
-		}
-	}
-
 	return lb, nil
 }
 
@@ -702,13 +660,29 @@ func createURLRewrite(filter *gatev1.HTTPURLRewriteFilter, pathMatch gatev1.HTTP
 	}, nil
 }
 
-func getProtocol(portSpec corev1.ServicePort) string {
+func getProtocol(portSpec corev1.ServicePort) (string, error) {
+	if portSpec.Protocol != corev1.ProtocolTCP {
+		return "", errors.New("only TCP protocol is supported")
+	}
+
+	if portSpec.AppProtocol == nil {
 		protocol := "http"
 		if portSpec.Port == 443 || strings.HasPrefix(portSpec.Name, "https") {
 			protocol = "https"
 		}
+		return protocol, nil
+	}
 
-	return protocol
+	switch ap := *portSpec.AppProtocol; ap {
+	case appProtocolH2C:
+		return "h2c", nil
+	case appProtocolWS:
+		return "http", nil
+	case appProtocolWSS:
+		return "https", nil
+	default:
+		return "", fmt.Errorf("unsupported application protocol %s", ap)
+	}
 }
 
 func mergeHTTPConfiguration(from, to *dynamic.Configuration) {

pkg/provider/kubernetes/gateway/kubernetes.go

@@ -36,6 +36,7 @@ import (
 
 const (
 	providerName = "kubernetesgateway"
+
 	controllerName = "traefik.io/gateway-controller"
 
 	groupCore    = "core"
@@ -48,6 +49,10 @@ const (
 	kindTCPRoute       = "TCPRoute"
 	kindTLSRoute       = "TLSRoute"
 	kindService        = "Service"
+
+	appProtocolH2C = "kubernetes.io/h2c"
+	appProtocolWS  = "kubernetes.io/ws"
+	appProtocolWSS = "kubernetes.io/wss"
 )
 
 // Provider holds configurations of the provider.
@@ -854,6 +859,79 @@ func (p *Provider) allowedNamespaces(gatewayNamespace string, routeNamespaces *g
 	return nil, fmt.Errorf("unsupported RouteSelectType: %q", *routeNamespaces.From)
 }
 
+type backendAddress struct {
+	Address string
+	Port    int32
+}
+
+func (p *Provider) getBackendAddresses(namespace string, ref gatev1.BackendRef) ([]backendAddress, corev1.ServicePort, error) {
+	if ref.Port == nil {
+		return nil, corev1.ServicePort{}, errors.New("port is required for Kubernetes Service reference")
+	}
+
+	service, exists, err := p.client.GetService(namespace, string(ref.Name))
+	if err != nil {
+		return nil, corev1.ServicePort{}, fmt.Errorf("getting service: %w", err)
+	}
+	if !exists {
+		return nil, corev1.ServicePort{}, errors.New("service not found")
+	}
+
+	var svcPort *corev1.ServicePort
+	for _, p := range service.Spec.Ports {
+		if p.Port == int32(*ref.Port) {
+			svcPort = &p
+			break
+		}
+	}
+	if svcPort == nil {
+		return nil, corev1.ServicePort{}, fmt.Errorf("service port %d not found", *ref.Port)
+	}
+
+	endpointSlices, err := p.client.ListEndpointSlicesForService(namespace, string(ref.Name))
+	if err != nil {
+		return nil, corev1.ServicePort{}, fmt.Errorf("getting endpointslices: %w", err)
+	}
+	if len(endpointSlices) == 0 {
+		return nil, corev1.ServicePort{}, errors.New("endpointslices not found")
+	}
+
+	uniqAddresses := map[string]struct{}{}
+	backendServers := make([]backendAddress, 0)
+	for _, endpointSlice := range endpointSlices {
+		var port int32
+		for _, p := range endpointSlice.Ports {
+			if svcPort.Name == *p.Name {
+				port = *p.Port
+				break
+			}
+		}
+		if port == 0 {
+			continue
+		}
+
+		for _, endpoint := range endpointSlice.Endpoints {
+			if endpoint.Conditions.Ready == nil || !*endpoint.Conditions.Ready {
+				continue
+			}
+
+			for _, address := range endpoint.Addresses {
+				if _, ok := uniqAddresses[address]; ok {
+					continue
+				}
+
+				uniqAddresses[address] = struct{}{}
+				backendServers = append(backendServers, backendAddress{
+					Address: address,
+					Port:    port,
+				})
+			}
+		}
+	}
+
+	return backendServers, *svcPort, nil
+}
+
 func supportedRouteKinds(protocol gatev1.ProtocolType, experimentalChannel bool) ([]gatev1.RouteGroupKind, []metav1.Condition) {
 	group := gatev1.Group(gatev1.GroupName)
 

pkg/provider/kubernetes/gateway/kubernetes_test.go

@@ -2452,6 +2452,104 @@ func TestLoadHTTPRoutes_backendExtensionRef(t *testing.T) {
 				TLS: &dynamic.TLSConfiguration{},
 			},
 		},
+		{
+			desc:  "Simple HTTPRoute, with appProtocol service",
+			paths: []string{"services.yml", "httproute/with_app_protocol_service.yml"},
+			groupKindBackendFuncs: map[string]map[string]BuildBackendFunc{
+				traefikv1alpha1.GroupName: {"TraefikService": func(name, namespace string) (string, *dynamic.Service, error) {
+					// func should never be executed in case of cross-provider reference.
+					return "", nil, errors.New("BOOM")
+				}},
+			},
+			entryPoints: map[string]Entrypoint{"web": {
+				Address: ":80",
+			}},
+			expected: &dynamic.Configuration{
+				UDP: &dynamic.UDPConfiguration{
+					Routers:  map[string]*dynamic.UDPRouter{},
+					Services: map[string]*dynamic.UDPService{},
+				},
+				TCP: &dynamic.TCPConfiguration{
+					Routers:           map[string]*dynamic.TCPRouter{},
+					Middlewares:       map[string]*dynamic.TCPMiddleware{},
+					Services:          map[string]*dynamic.TCPService{},
+					ServersTransports: map[string]*dynamic.TCPServersTransport{},
+				},
+				HTTP: &dynamic.HTTPConfiguration{
+					Routers: map[string]*dynamic.Router{
+						"default-http-multi-protocols-my-gateway-web-0-1c0cf64bde37d9d0df06": {
+							EntryPoints: []string{"web"},
+							Service:     "default-http-multi-protocols-my-gateway-web-0-1c0cf64bde37d9d0df06-wrr",
+							Rule:        "Host(`foo.com`) && Path(`/bar`)",
+							Priority:    100008,
+							RuleSyntax:  "v3",
+						},
+					},
+					Middlewares: map[string]*dynamic.Middleware{},
+					Services: map[string]*dynamic.Service{
+						"default-http-multi-protocols-my-gateway-web-0-1c0cf64bde37d9d0df06-wrr": {
+							Weighted: &dynamic.WeightedRoundRobin{
+								Services: []dynamic.WRRService{
+									{
+										Name:   "default-whoami-h2c-80",
+										Weight: ptr.To(1),
+									},
+									{
+										Name:   "default-whoami-ws-80",
+										Weight: ptr.To(1),
+									},
+									{
+										Name:   "default-whoami-wss-80",
+										Weight: ptr.To(1),
+									},
+								},
+							},
+						},
+						"default-whoami-h2c-80": {
+							LoadBalancer: &dynamic.ServersLoadBalancer{
+								Servers: []dynamic.Server{
+									{
+										URL: "h2c://10.10.0.13:80",
+									},
+								},
+								PassHostHeader: ptr.To(true),
+								ResponseForwarding: &dynamic.ResponseForwarding{
+									FlushInterval: ptypes.Duration(100 * time.Millisecond),
+								},
+							},
+						},
+						"default-whoami-ws-80": {
+							LoadBalancer: &dynamic.ServersLoadBalancer{
+								Servers: []dynamic.Server{
+									{
+										URL: "http://10.10.0.14:80",
+									},
+								},
+								PassHostHeader: ptr.To(true),
+								ResponseForwarding: &dynamic.ResponseForwarding{
+									FlushInterval: ptypes.Duration(100 * time.Millisecond),
+								},
+							},
+						},
+						"default-whoami-wss-80": {
+							LoadBalancer: &dynamic.ServersLoadBalancer{
+								Servers: []dynamic.Server{
+									{
+										URL: "https://10.10.0.15:80",
+									},
+								},
+								PassHostHeader: ptr.To(true),
+								ResponseForwarding: &dynamic.ResponseForwarding{
+									FlushInterval: ptypes.Duration(100 * time.Millisecond),
+								},
+							},
+						},
+					},
+					ServersTransports: map[string]*dynamic.ServersTransport{},
+				},
+				TLS: &dynamic.TLSConfiguration{},
+			},
+		},
 	}
 
 	for _, test := range testCases {

pkg/provider/kubernetes/gateway/tcproute.go

@@ -2,7 +2,6 @@ package gateway
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net"
 	"strconv"
@@ -252,87 +251,45 @@ func (p *Provider) loadTCPService(route *gatev1alpha2.TCPRoute, backendRef gatev
 	portStr := strconv.FormatInt(int64(port), 10)
 	serviceName = provider.Normalize(serviceName + "-" + portStr)
 
-	lb, err := p.loadTCPServers(namespace, backendRef)
-	if err != nil {
-		return serviceName, nil, &metav1.Condition{
-			Type:               string(gatev1.RouteConditionResolvedRefs),
-			Status:             metav1.ConditionFalse,
-			ObservedGeneration: route.Generation,
-			LastTransitionTime: metav1.Now(),
-			Reason:             string(gatev1.RouteReasonBackendNotFound),
-			Message:            fmt.Sprintf("Cannot load TCPRoute BackendRef %s/%s/%s/%s: %s", group, kind, namespace, backendRef.Name, err),
-		}
+	lb, errCondition := p.loadTCPServers(namespace, route, backendRef)
+	if errCondition != nil {
+		return serviceName, nil, errCondition
 	}
 
 	return serviceName, &dynamic.TCPService{LoadBalancer: lb}, nil
 }
 
-func (p *Provider) loadTCPServers(namespace string, backendRef gatev1.BackendRef) (*dynamic.TCPServersLoadBalancer, error) {
-	if backendRef.Port == nil {
-		return nil, errors.New("port is required for Kubernetes Service reference")
-	}
-
-	service, exists, err := p.client.GetService(namespace, string(backendRef.Name))
+func (p *Provider) loadTCPServers(namespace string, route *gatev1alpha2.TCPRoute, backendRef gatev1.BackendRef) (*dynamic.TCPServersLoadBalancer, *metav1.Condition) {
+	backendAddresses, svcPort, err := p.getBackendAddresses(namespace, backendRef)
 	if err != nil {
-		return nil, fmt.Errorf("getting service: %w", err)
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.GetGeneration(),
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonBackendNotFound),
+			Message:            fmt.Sprintf("Cannot load TCPRoute BackendRef %s/%s: %s", namespace, backendRef.Name, err),
 		}
-	if !exists {
-		return nil, errors.New("service not found")
 	}
 
-	var svcPort *corev1.ServicePort
-	for _, p := range service.Spec.Ports {
-		if p.Port == int32(*backendRef.Port) {
-			svcPort = &p
-			break
+	if svcPort.Protocol != corev1.ProtocolTCP {
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.GetGeneration(),
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonUnsupportedProtocol),
+			Message:            fmt.Sprintf("Cannot load TCPRoute BackendRef %s/%s: only TCP protocol is supported", namespace, backendRef.Name),
 		}
 	}
-	if svcPort == nil {
-		return nil, fmt.Errorf("service port %d not found", *backendRef.Port)
-	}
-
-	endpointSlices, err := p.client.ListEndpointSlicesForService(namespace, string(backendRef.Name))
-	if err != nil {
-		return nil, fmt.Errorf("getting endpointslices: %w", err)
-	}
-	if len(endpointSlices) == 0 {
-		return nil, errors.New("endpointslices not found")
-	}
 
 	lb := &dynamic.TCPServersLoadBalancer{}
 
-	addresses := map[string]struct{}{}
-	for _, endpointSlice := range endpointSlices {
-		var port int32
-		for _, p := range endpointSlice.Ports {
-			if svcPort.Name == *p.Name {
-				port = *p.Port
-				break
-			}
-		}
-		if port == 0 {
-			continue
-		}
-
-		for _, endpoint := range endpointSlice.Endpoints {
-			if endpoint.Conditions.Ready == nil || !*endpoint.Conditions.Ready {
-				continue
-			}
-
-			for _, address := range endpoint.Addresses {
-				if _, ok := addresses[address]; ok {
-					continue
-				}
-
-				addresses[address] = struct{}{}
+	for _, ba := range backendAddresses {
 		lb.Servers = append(lb.Servers, dynamic.TCPServer{
-					// TODO determine whether the servers needs TLS, from the port?
-					Address: net.JoinHostPort(address, strconv.Itoa(int(port))),
+			Address: net.JoinHostPort(ba.Address, strconv.Itoa(int(ba.Port))),
 		})
 	}
-		}
-	}
-
 	return lb, nil
 }
 

pkg/provider/kubernetes/gateway/tlsroute.go

@@ -3,6 +3,7 @@ package gateway
 import (
 	"context"
 	"fmt"
+	"net"
 	"regexp"
 	"strconv"
 	"strings"
@@ -10,6 +11,7 @@ import (
 	"github.com/rs/zerolog/log"
 	"github.com/traefik/traefik/v3/pkg/config/dynamic"
 	"github.com/traefik/traefik/v3/pkg/provider"
+	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	ktypes "k8s.io/apimachinery/pkg/types"
 	"k8s.io/utils/ptr"
@@ -251,21 +253,49 @@ func (p *Provider) loadTLSService(route *gatev1alpha2.TLSRoute, backendRef gatev
 	portStr := strconv.FormatInt(int64(port), 10)
 	serviceName = provider.Normalize(serviceName + "-" + portStr)
 
-	lb, err := p.loadTCPServers(namespace, backendRef)
-	if err != nil {
-		return serviceName, nil, &metav1.Condition{
-			Type:               string(gatev1.RouteConditionResolvedRefs),
-			Status:             metav1.ConditionFalse,
-			ObservedGeneration: route.Generation,
-			LastTransitionTime: metav1.Now(),
-			Reason:             string(gatev1.RouteReasonBackendNotFound),
-			Message:            fmt.Sprintf("Cannot load TLSRoute BackendRef %s/%s/%s/%s: %s", group, kind, namespace, backendRef.Name, err),
-		}
+	lb, errCondition := p.loadTLSServers(namespace, route, backendRef)
+	if errCondition != nil {
+		return serviceName, nil, errCondition
 	}
 
 	return serviceName, &dynamic.TCPService{LoadBalancer: lb}, nil
 }
 
+func (p *Provider) loadTLSServers(namespace string, route *gatev1alpha2.TLSRoute, backendRef gatev1.BackendRef) (*dynamic.TCPServersLoadBalancer, *metav1.Condition) {
+	backendAddresses, svcPort, err := p.getBackendAddresses(namespace, backendRef)
+	if err != nil {
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.GetGeneration(),
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonBackendNotFound),
+			Message:            fmt.Sprintf("Cannot load TLSRoute BackendRef %s/%s: %s", namespace, backendRef.Name, err),
+		}
+	}
+
+	if svcPort.Protocol != corev1.ProtocolTCP {
+		return nil, &metav1.Condition{
+			Type:               string(gatev1.RouteConditionResolvedRefs),
+			Status:             metav1.ConditionFalse,
+			ObservedGeneration: route.GetGeneration(),
+			LastTransitionTime: metav1.Now(),
+			Reason:             string(gatev1.RouteReasonUnsupportedProtocol),
+			Message:            fmt.Sprintf("Cannot load TLSRoute BackendRef %s/%s: only TCP protocol is supported", namespace, backendRef.Name),
+		}
+	}
+
+	lb := &dynamic.TCPServersLoadBalancer{}
+
+	for _, ba := range backendAddresses {
+		lb.Servers = append(lb.Servers, dynamic.TCPServer{
+			// TODO determine whether the servers needs TLS, from the port?
+			Address: net.JoinHostPort(ba.Address, strconv.Itoa(int(ba.Port))),
+		})
+	}
+	return lb, nil
+}
+
 func hostSNIRule(hostnames []gatev1.Hostname) string {
 	rules := make([]string, 0, len(hostnames))
 	uniqHostnames := map[gatev1.Hostname]struct{}{}