Support ResponseHeaderModifier filter

pkg/provider/kubernetes/gateway/fixtures/httproute/filter_response_header_modifier.yml

@@ -0,0 +1,62 @@
+---
+kind: GatewayClass
+apiVersion: gateway.networking.k8s.io/v1
+metadata:
+  name: my-gateway-class
+spec:
+  controllerName: traefik.io/gateway-controller
+
+---
+kind: Gateway
+apiVersion: gateway.networking.k8s.io/v1
+metadata:
+  name: my-gateway
+  namespace: default
+spec:
+  gatewayClassName: my-gateway-class
+  listeners: # Use GatewayClass defaults for listener definition.
+    - name: http
+      protocol: HTTP
+      port: 80
+      allowedRoutes:
+        kinds:
+          - kind: HTTPRoute
+            group: gateway.networking.k8s.io
+        namespaces:
+          from: Same
+
+---
+kind: HTTPRoute
+apiVersion: gateway.networking.k8s.io/v1
+metadata:
+  name: http-app-1
+  namespace: default
+spec:
+  parentRefs:
+    - name: my-gateway
+      kind: Gateway
+      group: gateway.networking.k8s.io
+  hostnames:
+    - "example.org"
+  rules:
+    - matches:
+        - path:
+            type: PathPrefix
+            value: /
+      backendRefs:
+        - name: whoami
+          port: 80
+          weight: 1
+          kind: Service
+          group: ""
+      filters:
+        - type: ResponseHeaderModifier
+          responseHeaderModifier:
+            set:
+              - name: X-Foo
+                value: Bar
+            add:
+              - name: X-Bar
+                value: Foo
+            remove:
+              - X-Baz

pkg/provider/kubernetes/gateway/httproute.go

@@ -316,6 +316,9 @@ func (p *Provider) loadMiddlewares(conf *dynamic.Configuration, namespace, route
 		case gatev1.HTTPRouteFilterRequestHeaderModifier:
 			middlewares[name] = createRequestHeaderModifier(filter.RequestHeaderModifier)
 
+		case gatev1.HTTPRouteFilterResponseHeaderModifier:
+			middlewares[name] = createResponseHeaderModifier(filter.ResponseHeaderModifier)
+
 		case gatev1.HTTPRouteFilterExtensionRef:
 			name, middleware, err := p.loadHTTPRouteFilterExtensionRef(namespace, filter.ExtensionRef)
 			if err != nil {
@@ -599,7 +602,29 @@ func createRequestHeaderModifier(filter *gatev1.HTTPHeaderFilter) *dynamic.Middl
 	}
 
 	return &dynamic.Middleware{
-		RequestHeaderModifier: &dynamic.RequestHeaderModifier{
+		RequestHeaderModifier: &dynamic.HeaderModifier{
+			Set:    sets,
+			Add:    adds,
+			Remove: filter.Remove,
+		},
+	}
+}
+
+// createResponseHeaderModifier does not enforce/check the configuration,
+// as the spec indicates that either the webhook or CEL (since v1.0 GA Release) should enforce that.
+func createResponseHeaderModifier(filter *gatev1.HTTPHeaderFilter) *dynamic.Middleware {
+	sets := map[string]string{}
+	for _, header := range filter.Set {
+		sets[string(header.Name)] = header.Value
+	}
+
+	adds := map[string]string{}
+	for _, header := range filter.Add {
+		adds[string(header.Name)] = header.Value
+	}
+
+	return &dynamic.Middleware{
+		ResponseHeaderModifier: &dynamic.HeaderModifier{
 			Set:    sets,
 			Add:    adds,
 			Remove: filter.Remove,

pkg/provider/kubernetes/gateway/kubernetes_test.go

@@ -1722,7 +1722,77 @@ func TestLoadHTTPRoutes(t *testing.T) {
 					},
 					Middlewares: map[string]*dynamic.Middleware{
 						"default-http-app-1-my-gateway-web-0-364ce6ec04c3d49b19c4-requestheadermodifier-0": {
-							RequestHeaderModifier: &dynamic.RequestHeaderModifier{
+							RequestHeaderModifier: &dynamic.HeaderModifier{
+								Set:    map[string]string{"X-Foo": "Bar"},
+								Add:    map[string]string{"X-Bar": "Foo"},
+								Remove: []string{"X-Baz"},
+							},
+						},
+					},
+					Services: map[string]*dynamic.Service{
+						"default-http-app-1-my-gateway-web-0-wrr": {
+							Weighted: &dynamic.WeightedRoundRobin{
+								Services: []dynamic.WRRService{
+									{
+										Name:   "default-whoami-80",
+										Weight: ptr.To(1),
+									},
+								},
+							},
+						},
+						"default-whoami-80": {
+							LoadBalancer: &dynamic.ServersLoadBalancer{
+								Servers: []dynamic.Server{
+									{
+										URL: "http://10.10.0.1:80",
+									},
+									{
+										URL: "http://10.10.0.2:80",
+									},
+								},
+								PassHostHeader: ptr.To(true),
+								ResponseForwarding: &dynamic.ResponseForwarding{
+									FlushInterval: ptypes.Duration(100 * time.Millisecond),
+								},
+							},
+						},
+					},
+					ServersTransports: map[string]*dynamic.ServersTransport{},
+				},
+				TLS: &dynamic.TLSConfiguration{},
+			},
+		},
+		{
+			desc:  "Simple HTTPRoute, response header modifier",
+			paths: []string{"services.yml", "httproute/filter_response_header_modifier.yml"},
+			entryPoints: map[string]Entrypoint{"web": {
+				Address: ":80",
+			}},
+			expected: &dynamic.Configuration{
+				UDP: &dynamic.UDPConfiguration{
+					Routers:  map[string]*dynamic.UDPRouter{},
+					Services: map[string]*dynamic.UDPService{},
+				},
+				TCP: &dynamic.TCPConfiguration{
+					Routers:           map[string]*dynamic.TCPRouter{},
+					Middlewares:       map[string]*dynamic.TCPMiddleware{},
+					Services:          map[string]*dynamic.TCPService{},
+					ServersTransports: map[string]*dynamic.TCPServersTransport{},
+				},
+				HTTP: &dynamic.HTTPConfiguration{
+					Routers: map[string]*dynamic.Router{
+						"default-http-app-1-my-gateway-web-0-364ce6ec04c3d49b19c4": {
+							EntryPoints: []string{"web"},
+							Service:     "default-http-app-1-my-gateway-web-0-wrr",
+							Rule:        "Host(`example.org`) && PathPrefix(`/`)",
+							Priority:    13,
+							RuleSyntax:  "v3",
+							Middlewares: []string{"default-http-app-1-my-gateway-web-0-364ce6ec04c3d49b19c4-responseheadermodifier-0"},
+						},
+					},
+					Middlewares: map[string]*dynamic.Middleware{
+						"default-http-app-1-my-gateway-web-0-364ce6ec04c3d49b19c4-responseheadermodifier-0": {
+							ResponseHeaderModifier: &dynamic.HeaderModifier{
 								Set:    map[string]string{"X-Foo": "Bar"},
 								Add:    map[string]string{"X-Bar": "Foo"},
 								Remove: []string{"X-Baz"},