feat: default remove accept encoding header

internal/gatewayapi/backendtrafficpolicy.go

@@ -1590,13 +1590,14 @@ func buildCompression(compression, compressor []*egv1a1.Compression) []*ir.Compr
 	// Handle the Compressor field first (higher priority)
 	if len(compressor) > 0 {
 		irCompression := make([]*ir.Compression, 0, len(compressor))
-		for _, c := range compressor {
+		for i, c := range compressor {
 			// Only add compression if the corresponding compressor not null
 			if (c.Type == egv1a1.GzipCompressorType && c.Gzip != nil) ||
 				(c.Type == egv1a1.BrotliCompressorType && c.Brotli != nil) ||
 				(c.Type == egv1a1.ZstdCompressorType && c.Zstd != nil) {
 				irCompression = append(irCompression, &ir.Compression{
-					Type: c.Type,
+					Type:        c.Type,
+					ChooseFirst: i == 0, // only the first compressor is marked as ChooseFirst
 				})
 			}
 		}
@@ -1608,9 +1609,10 @@ func buildCompression(compression, compressor []*egv1a1.Compression) []*ir.Compr
 		return nil
 	}
 	irCompression := make([]*ir.Compression, 0, len(compression))
-	for _, c := range compression {
+	for i, c := range compression {
 		irCompression = append(irCompression, &ir.Compression{
-			Type: c.Type,
+			Type:        c.Type,
+			ChooseFirst: i == 0, // only the first compressor is marked as ChooseFirst
 		})
 	}
 

internal/gatewayapi/testdata/backendtrafficpolicy-compression-json-merge.out.yaml

@@ -235,7 +235,8 @@ xdsIR:
           prefix: /
         traffic:
           compression:
-          - type: Brotli
+          - chooseFirst: true
+            type: Brotli
           - type: Zstd
     readyListener:
       address: 0.0.0.0

internal/gatewayapi/testdata/backendtrafficpolicy-compression-strategic-merge.out.yaml

@@ -374,7 +374,8 @@ xdsIR:
           prefix: /admin
         traffic:
           compression:
-          - type: Gzip
+          - chooseFirst: true
+            type: Gzip
       - destination:
           metadata:
             kind: HTTPRoute
@@ -406,7 +407,8 @@ xdsIR:
           prefix: /api
         traffic:
           compression:
-          - type: Brotli
+          - chooseFirst: true
+            type: Brotli
           - type: Zstd
       - destination:
           metadata:
@@ -439,7 +441,8 @@ xdsIR:
           prefix: /
         traffic:
           compression:
-          - type: Brotli
+          - chooseFirst: true
+            type: Brotli
           - type: Zstd
           - type: Gzip
     readyListener:

internal/gatewayapi/testdata/backendtrafficpolicy-compression.out.yaml

@@ -198,7 +198,8 @@ xdsIR:
           prefix: /
         traffic:
           compression:
-          - type: Brotli
+          - chooseFirst: true
+            type: Brotli
           - type: Gzip
           - type: Zstd
     readyListener:

internal/gatewayapi/testdata/backendtrafficpolicy-compressor-basic.enable.out.yaml

@@ -201,7 +201,8 @@ xdsIR:
           prefix: /
         traffic:
           compression:
-          - type: Brotli
+          - chooseFirst: true
+            type: Brotli
           - type: Gzip
           - type: Zstd
     readyListener:

internal/gatewayapi/testdata/backendtrafficpolicy-compressor-json-merge-enable-only-gzip.out.yaml

@@ -233,7 +233,8 @@ xdsIR:
           prefix: /
         traffic:
           compression:
-          - type: Gzip
+          - chooseFirst: true
+            type: Gzip
     readyListener:
       address: 0.0.0.0
       ipFamily: IPv4

internal/gatewayapi/testdata/backendtrafficpolicy-compressor-json-merge-enable-only-zstd.out.yaml

@@ -233,7 +233,8 @@ xdsIR:
           prefix: /
         traffic:
           compression:
-          - type: Zstd
+          - chooseFirst: true
+            type: Zstd
     readyListener:
       address: 0.0.0.0
       ipFamily: IPv4

internal/gatewayapi/testdata/backendtrafficpolicy-compressor-strategic-merge.out.yaml

@@ -375,7 +375,8 @@ xdsIR:
           prefix: /admin
         traffic:
           compression:
-          - type: Gzip
+          - chooseFirst: true
+            type: Gzip
       - destination:
           metadata:
             kind: HTTPRoute
@@ -407,7 +408,8 @@ xdsIR:
           prefix: /api
         traffic:
           compression:
-          - type: Brotli
+          - chooseFirst: true
+            type: Brotli
       - destination:
           metadata:
             kind: HTTPRoute
@@ -439,7 +441,8 @@ xdsIR:
           prefix: /
         traffic:
           compression:
-          - type: Brotli
+          - chooseFirst: true
+            type: Brotli
           - type: Gzip
     readyListener:
       address: 0.0.0.0

internal/ir/xds.go

@@ -891,6 +891,8 @@ type HeaderBasedSessionPersistence struct {
 type Compression struct {
 	// Type of compression to be used.
 	Type egv1a1.CompressorType `json:"type" yaml:"type"`
+	// ChooseFirst indicates this compressor is preferred when q-values in Accept-Encoding are equal.
+	ChooseFirst bool `json:"chooseFirst,omitempty" yaml:"chooseFirst,omitempty"`
 }
 
 // TrafficFeatures holds the information associated with the Backend Traffic Policy.

internal/xds/translator/compressor.go

@@ -8,6 +8,7 @@ package translator
 import (
 	"errors"
 	"fmt"
+	"slices"
 	"strings"
 
 	corev3 "github.com/envoyproxy/go-control-plane/envoy/config/core/v3"
@@ -51,11 +52,10 @@ func (*compressor) patchHCM(mgr *hcmv3.HttpConnectionManager, irListener *ir.HTT
 
 	for _, route := range irListener.Routes {
 		if route.Traffic != nil && route.Traffic.Compression != nil {
-			for i, irComp := range route.Traffic.Compression {
+			for _, irComp := range route.Traffic.Compression {
 				filterName := compressorFilterName(irComp.Type)
 				if !hcmContainsFilter(mgr, filterName) {
-					chooseFirst := i == 0
-					if filter, err = buildCompressorFilter(irComp, chooseFirst); err != nil {
+					if filter, err = buildCompressorFilter(irComp); err != nil {
 						return err
 					}
 					mgr.HttpFilters = append(mgr.HttpFilters, filter)
@@ -72,7 +72,7 @@ func compressorFilterName(compressorType egv1a1.CompressorType) string {
 }
 
 // buildCompressorFilter builds a compressor filter with the provided compressionType.
-func buildCompressorFilter(compression *ir.Compression, chooseFirst bool) (*hcmv3.HttpFilter, error) {
+func buildCompressorFilter(compression *ir.Compression) (*hcmv3.HttpFilter, error) {
 	var (
 		compressorProto *compressorv3.Compressor
 		extensionName   string
@@ -105,7 +105,7 @@ func buildCompressorFilter(compression *ir.Compression, chooseFirst bool) (*hcmv
 		},
 	}
 
-	if chooseFirst {
+	if compression.ChooseFirst {
 		compressorProto.ChooseFirst = true
 	}
 
@@ -151,6 +151,7 @@ func (*compressor) patchRoute(route *routev3.Route, irRoute *ir.HTTPRoute, _ *ir
 		route.TypedPerFilterConfig = make(map[string]*anypb.Any)
 	}
 
+	compressorProto := compressorPerRouteConfig()
 	for _, irComp := range irRoute.Traffic.Compression {
 		filterName := compressorFilterName(irComp.Type)
 		if _, ok := perFilterCfg[filterName]; ok {
@@ -160,14 +161,18 @@ func (*compressor) patchRoute(route *routev3.Route, irRoute *ir.HTTPRoute, _ *ir
 				filterName, route)
 		}
 
-		compressorProto := compressorPerRouteConfig()
 		if compressorAny, err = proto.ToAnyWithValidation(compressorProto); err != nil {
 			return err
 		}
 
 		route.TypedPerFilterConfig[filterName] = compressorAny
 	}
 
+	// Ensure accept-encoding from the request to prevent double compression.
+	if !slices.Contains(route.RequestHeadersToRemove, "accept-encoding") {
+		route.RequestHeadersToRemove = append(route.RequestHeadersToRemove, "accept-encoding")
+	}
+
 	return nil
 }
 

internal/xds/translator/testdata/out/xds-ir/compression.listeners.yaml

@@ -18,7 +18,6 @@
           name: envoy.filters.http.compressor.brotli
           typedConfig:
             '@type': type.googleapis.com/envoy.extensions.filters.http.compressor.v3.Compressor
-            chooseFirst: true
             compressorLibrary:
               name: envoy.compression.brotli.compressor
               typedConfig:

internal/xds/translator/testdata/out/xds-ir/compression.routes.yaml

@@ -23,6 +23,8 @@
               name: httproute-1
               namespace: default
       name: httproute/default/httproute-1/rule/0/match/0/gateway_envoyproxy_io
+      requestHeadersToRemove:
+      - accept-encoding
       route:
         cluster: httproute/default/httproute-1/rule/0
         upgradeConfigs:

test/e2e/tests/compression.go

@@ -16,6 +16,7 @@ import (
 	"net"
 	nethttp "net/http"
 	"net/http/httputil"
+	"strings"
 	"testing"
 
 	"github.com/andybalholm/brotli"
@@ -55,8 +56,14 @@ var CompressionTest = suite.ConformanceTest{
 			testCompression(t, suite, egv1a1.ZstdCompressorType)
 		})
 
-		t.Run("HTTPRoute with brotli compression chooseFirst", func(t *testing.T) {
-			testCompressionChooseFirst(t, suite, egv1a1.BrotliCompressorType)
+		t.Run("HTTPRoute with multiple compressors chooseFirst", func(t *testing.T) {
+			testCompression(
+				t,
+				suite,
+				egv1a1.BrotliCompressorType,
+				egv1a1.GzipCompressorType,
+				egv1a1.ZstdCompressorType,
+			)
 		})
 
 		t.Run("HTTPRoute without compression", func(t *testing.T) {
@@ -77,7 +84,7 @@ var CompressionTest = suite.ConformanceTest{
 				Request: http.Request{
 					Path: "/no-compression",
 					Headers: map[string]string{
-						"Accept-encoding": "gzip",
+						"accept-encoding": "gzip",
 					},
 				},
 				Response: http.Response{
@@ -92,7 +99,7 @@ var CompressionTest = suite.ConformanceTest{
 	},
 }
 
-func testCompression(t *testing.T, suite *suite.ConformanceTestSuite, compressionType egv1a1.CompressorType) {
+func testCompression(t *testing.T, suite *suite.ConformanceTestSuite, compressionTypes ...egv1a1.CompressorType) {
 	ns := "gateway-conformance-infra"
 	routeNN := types.NamespacedName{Name: "compression", Namespace: ns}
 	gwNN := types.NamespacedName{Name: "same-namespace", Namespace: ns}
@@ -106,52 +113,29 @@ func testCompression(t *testing.T, suite *suite.ConformanceTestSuite, compressio
 	}
 	BackendTrafficPolicyMustBeAccepted(t, suite.Client, types.NamespacedName{Name: "compression", Namespace: ns}, suite.ControllerName, ancestorRef)
 
-	encoding := ContentEncoding(compressionType)
-	expectedResponse := http.ExpectedResponse{
-		Request: http.Request{
-			Path: "/compression",
-			Headers: map[string]string{
-				"Accept-encoding": encoding,
-			},
-		},
-		Response: http.Response{
-			StatusCodes: []int{200},
-			Headers: map[string]string{
-				"content-encoding": encoding,
-			},
-		},
-		Namespace: ns,
-	}
-	roundTripper := &CompressionRoundTripper{Debug: suite.Debug, TimeoutConfig: suite.TimeoutConfig}
-	http.MakeRequestAndExpectEventuallyConsistentResponse(t, roundTripper, suite.TimeoutConfig, gwAddr, expectedResponse)
-}
-
-func testCompressionChooseFirst(t *testing.T, suite *suite.ConformanceTestSuite, compressionType egv1a1.CompressorType) {
-	ns := "gateway-conformance-infra"
-	routeNN := types.NamespacedName{Name: "compression", 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),
+	encodings := make([]string, len(compressionTypes))
+	for i, ct := range compressionTypes {
+		encodings[i] = ContentEncoding(ct)
 	}
-	BackendTrafficPolicyMustBeAccepted(t, suite.Client, types.NamespacedName{Name: "compression", Namespace: ns}, suite.ControllerName, ancestorRef)
 
-	encoding := ContentEncoding(compressionType)
+	acceptEncoding := strings.Join(encodings, ", ")
 	expectedResponse := http.ExpectedResponse{
 		Request: http.Request{
 			Path: "/compression",
 			Headers: map[string]string{
-				"Accept-encoding": "gzip, br, zstd",
+				"accept-encoding": acceptEncoding,
+			},
+		},
+		ExpectedRequest: &http.ExpectedRequest{
+			Request: http.Request{
+				Path: "/compression",
 			},
+			AbsentHeaders: []string{"accept-encoding"},
 		},
 		Response: http.Response{
 			StatusCodes: []int{200},
 			Headers: map[string]string{
-				"content-encoding": encoding,
+				"content-encoding": encodings[0],
 			},
 		},
 		Namespace: ns,