test: add e2e test for stripTrailingHostDot

Sends a request with a trailing dot in the Host header through a
listener with ClientTrafficPolicy headers.host.stripTrailingHostDot
enabled, and verifies the route matches and the backend receives the
normalized Host header.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Signed-off-by: Salim Boulkour <salim.boulkour@algolia.com>

Author: sboulkour

test/e2e/testdata/host-normalization.yaml

@@ -0,0 +1,32 @@
+apiVersion: gateway.envoyproxy.io/v1alpha1
+kind: ClientTrafficPolicy
+metadata:
+  name: strip-trailing-host-dot-ctp
+  namespace: gateway-conformance-infra
+spec:
+  targetRefs:
+    - group: gateway.networking.k8s.io
+      kind: Gateway
+      name: same-namespace
+  headers:
+    host:
+      stripTrailingHostDot: true
+---
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: http-host-normalization
+  namespace: gateway-conformance-infra
+spec:
+  parentRefs:
+    - name: same-namespace
+  hostnames:
+    - host-normalization.example.com
+  rules:
+    - matches:
+        - path:
+            type: PathPrefix
+            value: /host-normalization
+      backendRefs:
+        - name: infra-backend-v1
+          port: 8080

test/e2e/tests/host_normalization.go

@@ -0,0 +1,83 @@
+// Copyright Envoy Gateway Authors
+// SPDX-License-Identifier: Apache-2.0
+// The full text of the Apache license is available in the LICENSE file at
+// the root of the repo.
+
+//go:build e2e
+
+package tests
+
+import (
+	"testing"
+
+	"k8s.io/apimachinery/pkg/types"
+	gwapiv1 "sigs.k8s.io/gateway-api/apis/v1"
+	"sigs.k8s.io/gateway-api/conformance/utils/http"
+	"sigs.k8s.io/gateway-api/conformance/utils/kubernetes"
+	"sigs.k8s.io/gateway-api/conformance/utils/suite"
+
+	"github.com/envoyproxy/gateway/internal/gatewayapi"
+	"github.com/envoyproxy/gateway/internal/gatewayapi/resource"
+)
+
+func init() {
+	ConformanceTests = append(ConformanceTests, HostNormalizationTest)
+}
+
+var HostNormalizationTest = suite.ConformanceTest{
+	ShortName:   "HostNormalization",
+	Description: "Strip the trailing dot from the Host header before route matching",
+	Manifests:   []string{"testdata/host-normalization.yaml"},
+	Test: func(t *testing.T, suite *suite.ConformanceTestSuite) {
+		ns := "gateway-conformance-infra"
+		routeNN := types.NamespacedName{Name: "http-host-normalization", Namespace: ns}
+		gwNN := types.NamespacedName{Name: "same-namespace", Namespace: ns}
+		gwAddr := kubernetes.GatewayAndRoutesMustBeAccepted(t, suite.Client, suite.TimeoutConfig, suite.ControllerName, kubernetes.NewGatewayRef(gwNN), &gwapiv1.HTTPRoute{}, false, routeNN)
+
+		ancestorRef := gwapiv1.ParentReference{
+			Group:     gatewayapi.GroupPtr(gwapiv1.GroupName),
+			Kind:      gatewayapi.KindPtr(resource.KindGateway),
+			Namespace: gatewayapi.NamespacePtr(gwNN.Namespace),
+			Name:      gwapiv1.ObjectName(gwNN.Name),
+		}
+		ClientTrafficPolicyMustBeAccepted(t, suite.Client, types.NamespacedName{Name: "strip-trailing-host-dot-ctp", Namespace: ns}, suite.ControllerName, ancestorRef)
+
+		t.Run("host without trailing dot should match the route", func(t *testing.T) {
+			expected := http.ExpectedResponse{
+				Request: http.Request{
+					Host: "host-normalization.example.com",
+					Path: "/host-normalization",
+				},
+				Response: http.Response{
+					StatusCodes: []int{200},
+				},
+				Namespace: ns,
+			}
+
+			http.MakeRequestAndExpectEventuallyConsistentResponse(t, suite.RoundTripper, suite.TimeoutConfig, gwAddr, expected)
+		})
+
+		t.Run("host with trailing dot should be normalized and match the route", func(t *testing.T) {
+			expected := http.ExpectedResponse{
+				Request: http.Request{
+					Host: "host-normalization.example.com.",
+					Path: "/host-normalization",
+				},
+				// The trailing dot is stripped before routing, so the backend
+				// receives the normalized Host header.
+				ExpectedRequest: &http.ExpectedRequest{
+					Request: http.Request{
+						Host: "host-normalization.example.com",
+						Path: "/host-normalization",
+					},
+				},
+				Response: http.Response{
+					StatusCodes: []int{200},
+				},
+				Namespace: ns,
+			}
+
+			http.MakeRequestAndExpectEventuallyConsistentResponse(t, suite.RoundTripper, suite.TimeoutConfig, gwAddr, expected)
+		})
+	},
+}