Add support for ResponseHeaderModifier for HTTPRouteRule objects (#1880)

Add support for ResponseHeaderModifier for HTTPRouteRule objects

Problem: Users want to add, set, and remove response headers.

Solution: Use add_header NGINX directive to support ResponseHeaderModifier.

---- 

Co-authored-by: kaihsun <[email protected]>

Author: salonichf5

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

examples/http-header-filter/README.md renamed to examples/http-request-header-filter/README.md

@@ -22,7 +22,7 @@ headers to the request.
    GW_PORT=<port number>
    ```
 
-## 2. Deploy the Cafe Application
+## 2. Deploy the Headers Application
 
 1. Create the headers Deployment and Service:
 

examples/http-header-filter/echo-route.yaml renamed to examples/http-request-header-filter/echo-route.yaml

@@ -0,0 +1,3 @@
+# HTTP Response Headers
+
+This directory contains the YAML files used in the [HTTP Response Headers](https://docs.nginx.com/nginx-gateway-fabric/how-to/traffic-management/response-headers.md) guide.

examples/http-header-filter/gateway.yaml renamed to examples/http-request-header-filter/gateway.yaml

@@ -0,0 +1,10 @@
+apiVersion: gateway.networking.k8s.io/v1
+kind: Gateway
+metadata:
+  name: gateway
+spec:
+  gatewayClassName: nginx
+  listeners:
+  - name: http
+    port: 80
+    protocol: HTTP

examples/http-header-filter/headers.yaml renamed to examples/http-request-header-filter/headers.yaml

@@ -0,0 +1,70 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: headers
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: headers
+  template:
+    metadata:
+      labels:
+        app: headers
+    spec:
+      containers:
+      - name: headers
+        image: nginx
+        ports:
+        - containerPort: 8080
+        volumeMounts:
+        - name: config-volume
+          mountPath: /etc/nginx
+          readOnly: true
+      volumes:
+      - name: config-volume
+        configMap:
+          name: headers-config
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: headers-config
+# yamllint disable rule:indentation
+data:
+  nginx.conf: |-
+    user  nginx;
+    worker_processes  1;
+
+    pid        /var/run/nginx.pid;
+
+    events {}
+
+    http {
+        default_type text/plain;
+
+        server {
+            listen 8080;
+
+            add_header X-Header-Unmodified "unmodified";
+            add_header X-Header-Add "add-to";
+            add_header X-Header-Set "overwrite";
+            add_header X-Header-Remove "remove";
+
+            return 200 "ok";
+        }
+    }
+# yamllint enable rule:indentation
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: headers
+spec:
+  ports:
+  - port: 80
+    targetPort: 8080
+    protocol: TCP
+    name: http
+  selector:
+    app: headers

examples/http-response-header-filter/README.md

@@ -0,0 +1,29 @@
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: headers
+spec:
+  parentRefs:
+  - name: gateway
+    sectionName: http
+  hostnames:
+  - "cafe.example.com"
+  rules:
+  - matches:
+    - path:
+        type: PathPrefix
+        value: /headers
+    filters:
+    - type: ResponseHeaderModifier
+      responseHeaderModifier:
+        set:
+        - name: X-Header-Set
+          value: overwritten-value
+        add:
+        - name: X-Header-Add
+          value: this-is-the-appended-value
+        remove:
+        - X-Header-Remove
+    backendRefs:
+    - name: headers
+      port: 80

examples/http-response-header-filter/gateway.yaml

@@ -0,0 +1,18 @@
+apiVersion: gateway.networking.k8s.io/v1
+kind: HTTPRoute
+metadata:
+  name: headers
+spec:
+  parentRefs:
+  - name: gateway
+    sectionName: http
+  hostnames:
+  - "cafe.example.com"
+  rules:
+  - matches:
+    - path:
+        type: PathPrefix
+        value: /headers
+    backendRefs:
+    - name: headers
+      port: 80

examples/http-response-header-filter/headers.yaml

@@ -16,10 +16,12 @@ type Location struct {
 	Path            string
 	ProxyPass       string
 	HTTPMatchKey    string
+	HTTPMatchVar    string
+	Rewrites        []string
 	ProxySetHeaders []Header
 	ProxySSLVerify  *ProxySSLVerify
 	Return          *Return
-	Rewrites        []string
+	ResponseHeaders ResponseHeaders
 	GRPC            bool
 }
 
@@ -29,6 +31,13 @@ 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

examples/http-response-header-filter/http-route-filters.yaml

@@ -294,6 +294,7 @@ func updateLocationsForFilters(
 
 	rewrites := createRewritesValForRewriteFilter(filters.RequestURLRewrite, path)
 	proxySetHeaders := generateProxySetHeaders(&matchRule.Filters, grpc)
+	responseHeaders := generateResponseHeaders(&matchRule.Filters)
 	for i := range buildLocations {
 		if rewrites != nil {
 			if rewrites.Rewrite != "" {
@@ -308,6 +309,7 @@ func updateLocationsForFilters(
 			generateProtocolString(buildLocations[i].ProxySSLVerify, grpc),
 			grpc,
 		)
+		buildLocations[i].ResponseHeaders = responseHeaders
 		buildLocations[i].ProxyPass = proxyPass
 		buildLocations[i].GRPC = grpc
 	}
@@ -578,11 +580,11 @@ func generateProxySetHeaders(filters *dataplane.HTTPFilters, grpc bool) []http.H
 	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
@@ -596,7 +598,25 @@ func generateProxySetHeaders(filters *dataplane.HTTPFilters, grpc bool) []http.H
 	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{}
+	}
+
+	headerFilter := filters.ResponseHeaderModifiers
+	responseRemoveHeaders := make([]string, len(headerFilter.Remove))
+
+	// Make a deep copy to prevent the slice from being accidentally modified.
+	copy(responseRemoveHeaders, headerFilter.Remove)
+
+	return http.ResponseHeaders{
+		Add:    createHeaders(headerFilter.Add),
+		Set:    createHeaders(headerFilter.Set),
+		Remove: responseRemoveHeaders,
+	}
+}
+
+func createHeadersWithVarName(headers []dataplane.HTTPHeader) []http.Header {
 	locHeaders := make([]http.Header, 0, len(headers))
 	for _, h := range headers {
 		mapVarName := "${" + generateAddHeaderMapVariableName(h.Name) + "}"
@@ -608,7 +628,7 @@ 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{

examples/http-response-header-filter/http-route.yaml

@@ -58,6 +58,16 @@ server {
         {{ $proxyOrGRPC }}_set_header {{ $h.Name }} "{{ $h.Value }}";
             {{- end }}
         {{ $proxyOrGRPC }}_pass {{ $l.ProxyPass }};
+            {{ 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;
             {{- if $l.ProxySSLVerify }}
         {{ $proxyOrGRPC }}_ssl_server_name on;