feat(conformance): add conformance test for verifying x-gateway-destination-endpoint-served

conformance/resources/base.yaml

@@ -200,7 +200,7 @@ spec:
       terminationGracePeriodSeconds: 130
       containers:
       - name: epp
-        image: us-central1-docker.pkg.dev/k8s-staging-images/gateway-api-inference-extension/epp:v20251105-cbb8928
+        image: us-central1-docker.pkg.dev/k8s-staging-images/gateway-api-inference-extension/epp:v20251119-2aaf2a6
         imagePullPolicy: Always
         args:
         - --pool-name
@@ -298,7 +298,7 @@ spec:
       terminationGracePeriodSeconds: 130
       containers:
       - name: epp
-        image: us-central1-docker.pkg.dev/k8s-staging-images/gateway-api-inference-extension/epp:v20251105-cbb8928
+        image: us-central1-docker.pkg.dev/k8s-staging-images/gateway-api-inference-extension/epp:v20251119-2aaf2a6
         imagePullPolicy: Always
         args:
         - --pool-name
@@ -507,7 +507,7 @@ spec:
       terminationGracePeriodSeconds: 130
       containers:
       - name: epp
-        image: us-central1-docker.pkg.dev/k8s-staging-images/gateway-api-inference-extension/epp:v20251105-cbb8928
+        image: us-central1-docker.pkg.dev/k8s-staging-images/gateway-api-inference-extension/epp:v20251119-2aaf2a6
         imagePullPolicy: Always
         args:
         - --pool-name
@@ -560,6 +560,7 @@ data:
     kind: EndpointPickerConfig
     plugins:
     - type: header-based-testing-filter
+    - type: destination-endpoint-served-verifier
     schedulingProfiles:
     - name: conformance-profile
       plugins:

conformance/tests/gateway_destination_endpoint_served.go

@@ -0,0 +1,109 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tests
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"k8s.io/apimachinery/pkg/types"
+	gwhttp "sigs.k8s.io/gateway-api/conformance/utils/http"
+	"sigs.k8s.io/gateway-api/conformance/utils/suite"
+	"sigs.k8s.io/gateway-api/pkg/features"
+
+	"sigs.k8s.io/gateway-api-inference-extension/conformance/resources"
+	k8sutils "sigs.k8s.io/gateway-api-inference-extension/conformance/utils/kubernetes"
+	"sigs.k8s.io/gateway-api-inference-extension/pkg/epp/requestcontrol/plugins/test"
+	testscheduling "sigs.k8s.io/gateway-api-inference-extension/pkg/epp/scheduling/framework/plugins/test"
+)
+
+func init() {
+	ConformanceTests = append(ConformanceTests, GatewayDestinationEndpointServed)
+}
+
+var GatewayDestinationEndpointServed = suite.ConformanceTest{
+	ShortName:   "GatewayDestinationEndpointServed",
+	Description: "A conformance test to verify that the gateway correctly reports the endpoint that served the request.",
+	Manifests:   []string{"tests/gateway_destination_endpoint_served.yaml"},
+	Features: []features.FeatureName{
+		features.FeatureName("SupportInferencePool"),
+		features.SupportGateway,
+	},
+	Test: func(t *testing.T, s *suite.ConformanceTestSuite) {
+		const (
+			hostname = "primary.example.com"
+			path     = "/destination-endpoint-served-test"
+		)
+
+		httpRouteNN := types.NamespacedName{Name: "httproute-for-destination-endpoint-served", Namespace: resources.AppBackendNamespace}
+		gatewayNN := resources.PrimaryGatewayNN
+		poolNN := resources.PrimaryInferencePoolNN
+		backendPodLabels := map[string]string{"app": resources.PrimaryModelServerAppLabel}
+
+		t.Log("Verifying HTTPRoute and InferencePool are accepted and the Gateway has an address.")
+		k8sutils.HTTPRouteMustBeAcceptedAndResolved(t, s.Client, s.TimeoutConfig, httpRouteNN, gatewayNN)
+		k8sutils.InferencePoolMustBeAcceptedByParent(t, s.Client, poolNN, gatewayNN)
+		gwAddr := k8sutils.GetGatewayEndpoint(t, s.Client, s.TimeoutConfig, gatewayNN)
+
+		t.Logf("Fetching backend pods with labels: %v", backendPodLabels)
+		pods, err := k8sutils.GetPodsWithLabel(t, s.Client, resources.AppBackendNamespace, backendPodLabels, s.TimeoutConfig)
+		require.NoError(t, err, "Failed to get backend pods")
+		require.Len(t, pods, resources.ModelServerPodReplicas, "Expected to find %d backend pods, but found %d.", resources.ModelServerPodReplicas, len(pods))
+
+		podIPs := make([]string, len(pods))
+		podNames := make([]string, len(pods))
+		for i, pod := range pods {
+			podIPs[i] = pod.Status.PodIP
+			podNames[i] = pod.Name
+		}
+
+		requestBody := `{
+            "model": "conformance-fake-model",
+            "prompt": "Write as if you were a critic: San Francisco"
+        }`
+		t.Run("Request is served by the selected backend pod", func(t *testing.T) {
+			for i := 0; i < len(pods); i++ {
+				gwhttp.MakeRequestAndExpectEventuallyConsistentResponse(
+					t,
+					s.RoundTripper,
+					s.TimeoutConfig,
+					gwAddr,
+					gwhttp.ExpectedResponse{
+						Request: gwhttp.Request{
+							Host:   hostname,
+							Path:   path,
+							Method: http.MethodPost,
+							Body:   requestBody,
+							Headers: map[string]string{
+								testscheduling.HeaderTestEppEndPointSelectionKey: podIPs[i],
+							},
+						},
+						Response: gwhttp.Response{
+							StatusCodes: []int{http.StatusOK},
+							Headers: map[string]string{
+								test.ConformanceTestResultHeader: podIPs[i] + ":3000", // The echo server's port is 3000.
+							},
+						},
+						Backend:   podNames[i],
+						Namespace: resources.AppBackendNamespace,
+					},
+				)
+			}
+		})
+	},
+}

conformance/tests/gateway_destination_endpoint_served.yaml

@@ -0,0 +1,23 @@
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: httproute-for-destination-endpoint-served
+  namespace: inference-conformance-app-backend
+spec:
+  parentRefs:
+  - group: gateway.networking.k8s.io
+    kind: Gateway
+    name: conformance-primary
+    namespace: inference-conformance-infra
+    sectionName: http
+  hostnames:
+  - "primary.example.com"
+  rules:
+  - backendRefs:
+    - group: inference.networking.k8s.io
+      kind: InferencePool
+      name: primary-inference-pool
+    matches:
+    - path:
+        type: PathPrefix
+        value: /destination-endpoint-served-test