Add support for ResponseHeaderModifier for HTTPRouteRule objects

conformance/Makefile

@@ -5,7 +5,7 @@ NGINX_PREFIX = $(PREFIX)/nginx
 NGINX_PLUS_PREFIX ?= $(PREFIX)/nginx-plus
 GW_API_VERSION ?= 1.0.0
 GATEWAY_CLASS = nginx
-SUPPORTED_FEATURES = HTTPRouteQueryParamMatching,HTTPRouteMethodMatching,HTTPRoutePortRedirect,HTTPRouteSchemeRedirect,HTTPRouteHostRewrite,HTTPRoutePathRewrite,GatewayPort8080
+SUPPORTED_FEATURES = HTTPRouteQueryParamMatching,HTTPRouteMethodMatching,HTTPRoutePortRedirect,HTTPRouteSchemeRedirect,HTTPRouteHostRewrite,HTTPRoutePathRewrite,GatewayPort8080,HTTPRouteResponseHeaderModification
 KIND_IMAGE ?= $(shell grep -m1 'FROM kindest/node' <tests/Dockerfile | awk -F'[ ]' '{print $$2}')
 KIND_KUBE_CONFIG=$${HOME}/.kube/kind/config
 CONFORMANCE_TAG = latest

internal/mode/static/nginx/config/http/config.go

@@ -19,6 +19,7 @@ type Location struct {
 	HTTPMatchVar    string
 	Rewrites        []string
 	ProxySetHeaders []Header
+	ResponseHeaders ResponseHeaders
 }
 
 // Header defines a HTTP header to be passed to the proxied server.
@@ -27,6 +28,13 @@ type Header struct {
 	Value string
 }
 
+// ResponseHeaders holds all response headers to be added, set, or removed.
+type ResponseHeaders struct {
+	Add    []Header
+	Set    []Header
+	Remove []string
+}
+
 // Return represents an HTTP return.
 type Return struct {
 	Body string

internal/mode/static/nginx/config/servers.go

@@ -247,13 +247,15 @@ func updateLocationsForFilters(
 
 	rewrites := createRewritesValForRewriteFilter(filters.RequestURLRewrite, path)
 	proxySetHeaders := generateProxySetHeaders(&matchRule.Filters)
+	responseHeaders := generateResponseHeaders(&matchRule.Filters)
 	for i := range buildLocations {
 		if rewrites != nil {
 			if rewrites.Rewrite != "" {
 				buildLocations[i].Rewrites = append(buildLocations[i].Rewrites, rewrites.Rewrite)
 			}
 		}
 		buildLocations[i].ProxySetHeaders = proxySetHeaders
+		buildLocations[i].ResponseHeaders = responseHeaders
 		buildLocations[i].ProxySSLVerify = createProxyTLSFromBackends(matchRule.BackendGroup.Backends)
 		proxyPass := createProxyPass(
 			matchRule.BackendGroup,
@@ -517,11 +519,11 @@ func generateProxySetHeaders(filters *dataplane.HTTPFilters) []http.Header {
 	headerLen := len(headerFilter.Add) + len(headerFilter.Set) + len(headerFilter.Remove) + len(headers)
 	proxySetHeaders := make([]http.Header, 0, headerLen)
 	if len(headerFilter.Add) > 0 {
-		addHeaders := convertAddHeaders(headerFilter.Add)
+		addHeaders := createHeadersWithVarName(headerFilter.Add)
 		proxySetHeaders = append(proxySetHeaders, addHeaders...)
 	}
 	if len(headerFilter.Set) > 0 {
-		setHeaders := convertSetHeaders(headerFilter.Set)
+		setHeaders := createHeaders(headerFilter.Set)
 		proxySetHeaders = append(proxySetHeaders, setHeaders...)
 	}
 	// If the value of a header field is an empty string then this field will not be passed to a proxied server
@@ -535,7 +537,38 @@ func generateProxySetHeaders(filters *dataplane.HTTPFilters) []http.Header {
 	return append(proxySetHeaders, headers...)
 }
 
-func convertAddHeaders(headers []dataplane.HTTPHeader) []http.Header {
+func generateResponseHeaders(filters *dataplane.HTTPFilters) http.ResponseHeaders {
+	if filters == nil || filters.ResponseHeaderModifiers == nil {
+		return http.ResponseHeaders{
+			Add:    []http.Header{},
+			Set:    []http.Header{},
+			Remove: []string{},
+		}
+	}
+
+	headerFilter := filters.ResponseHeaderModifiers
+	responseAddHeaders := make([]http.Header, 0, len(headerFilter.Add))
+	responseSetHeaders := make([]http.Header, 0, len(headerFilter.Set))
+	responseRemoveHeaders := make([]string, len(headerFilter.Remove))
+	if len(headerFilter.Add) > 0 {
+		addHeaders := createHeaders(headerFilter.Add)
+		responseAddHeaders = append(responseAddHeaders, addHeaders...)
+	}
+	if len(headerFilter.Set) > 0 {
+		setHeaders := createHeaders(headerFilter.Set)
+		responseSetHeaders = append(responseSetHeaders, setHeaders...)
+	}
+	// Make a deep copy to prevent the slice from being accidentally modified.
+	copy(responseRemoveHeaders, headerFilter.Remove)
+
+	return http.ResponseHeaders{
+		Add:    responseAddHeaders,
+		Set:    responseSetHeaders,
+		Remove: responseRemoveHeaders,
+	}
+}
+
+func createHeadersWithVarName(headers []dataplane.HTTPHeader) []http.Header {
 	locHeaders := make([]http.Header, 0, len(headers))
 	for _, h := range headers {
 		mapVarName := "${" + generateAddHeaderMapVariableName(h.Name) + "}"
@@ -547,7 +580,7 @@ func convertAddHeaders(headers []dataplane.HTTPHeader) []http.Header {
 	return locHeaders
 }
 
-func convertSetHeaders(headers []dataplane.HTTPHeader) []http.Header {
+func createHeaders(headers []dataplane.HTTPHeader) []http.Header {
 	locHeaders := make([]http.Header, 0, len(headers))
 	for _, h := range headers {
 		locHeaders = append(locHeaders, http.Header{

internal/mode/static/nginx/config/servers_template.go

@@ -50,6 +50,16 @@ server {
             {{ range $h := $l.ProxySetHeaders }}
         proxy_set_header {{ $h.Name }} "{{ $h.Value }}";
             {{- end }}
+            {{ range $h := $l.ResponseHeaders.Add }}
+        add_header {{ $h.Name }} "{{ $h.Value }}" always;
+            {{- end }}
+            {{ range $h := $l.ResponseHeaders.Set }}
+        proxy_hide_header {{ $h.Name }};
+        add_header {{ $h.Name }} "{{ $h.Value }}" always;
+            {{- end }}
+            {{ range $h := $l.ResponseHeaders.Remove }}
+        proxy_hide_header {{ $h }};
+            {{- end }}
         proxy_http_version 1.1;
         proxy_pass {{ $l.ProxyPass }};
             {{- if $l.ProxySSLVerify }}