Add support for RequestHeaderModifier for HTTPRouteRule objects

deploy/manifests/nginx-conf.yaml

@@ -15,6 +15,10 @@ data:
     http {
       include /etc/nginx/conf.d/*.conf;
       js_import /usr/lib/nginx/modules/njs/httpmatches.js;
+      proxy_headers_hash_bucket_size 512;
+      proxy_headers_hash_max_size 1024;
       server_names_hash_bucket_size 256;
       server_names_hash_max_size 1024;
+      variables_hash_bucket_size 512;
+      variables_hash_max_size 1024;
     }

docs/gateway-api-compatibility.md

@@ -111,7 +111,8 @@ Fields:
     * `filters`
         * `type` - supported.
         * `requestRedirect` - supported except for the experimental `path` field. If multiple filters with `requestRedirect` are configured, NGINX Kubernetes Gateway will choose the first one and ignore the rest.
-        * `requestHeaderModifier`, `requestMirror`, `urlRewrite`, `extensionRef` - not supported.
+        * `requestHeaderModifier` - supported. If multiple filters with `requestHeaderModifier` are configured, NGINX Kubernetes Gateway will choose the first one and ignore the rest.
+        * `responseHeaderModifier`, `requestMirror`, `urlRewrite`, `extensionRef` - not supported.
     * `backendRefs` - partially supported. Backend ref `filters` are not supported.
 * `status`
   * `parents`

examples/http-header-filter/README.md

@@ -0,0 +1,70 @@
+# Example
+
+In this example we will deploy NGINX Kubernetes Gateway and configure traffic routing for a simple echo server.
+We will use `HTTPRoute` resources to route traffic to the echo server, using the RequestHeaderModifier filter to modify 
+headers to the request.
+## Running the Example
+
+## 1. Deploy NGINX Kubernetes Gateway
+
+1. Follow the [installation instructions](/docs/installation.md) to deploy NGINX Gateway.
+
+1. Save the public IP address of NGINX Kubernetes Gateway into a shell variable:
+
+   ```
+   GW_IP=XXX.YYY.ZZZ.III
+   ```
+
+1. Save the port of NGINX Kubernetes Gateway:
+
+   ```
+   GW_PORT=<port number>
+   ```
+
+## 2. Deploy the Cafe Application  
+
+1. Create the headers Deployment and Service:
+
+   ```
+   kubectl apply -f headers.yaml
+   ```
+
+1. Check that the Pod is running in the `default` namespace:
+
+   ```
+   kubectl -n default get pods
+   NAME                      READY   STATUS    RESTARTS   AGE
+   headers-6f4b79b975-2sb28   1/1     Running   0          12s
+   ```
+
+## 3. Configure Routing
+
+1. Create the `Gateway`:
+
+   ```
+   kubectl apply -f gateway.yaml
+   ```
+
+1. Create the `HTTPRoute` resources:
+
+   ```
+   kubectl apply -f echo-route.yaml
+   ```
+
+## 4. Test the Application
+
+To access the application, we will use `curl` to send requests to the `headers` Service, including sending headers with 
+our request.
+Notice our configured header values can be seen in the `requestHeaders` section below, and that the `User-Agent` header 
+is absent.
+
+```
+curl -s --resolve echo.example.com:$GW_PORT:$GW_IP http://echo.example.com:$GW_PORT/headers -H "My-Cool-Header:my-client-value" -H "My-Overwrite-Header:dont-see-this"
+Headers:
+  header 'Accept-Encoding' is 'compress'
+  header 'My-cool-header' is 'my-client-value, this-is-an-appended-value'
+  header 'My-Overwrite-Header' is 'this-is-the-only-value'
+  header 'Host' is 'echo.example.com'
+  header 'Connection' is 'close'
+  header 'Accept' is '*/*'
+```

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

@@ -0,0 +1,31 @@
+apiVersion: gateway.networking.k8s.io/v1beta1
+kind: HTTPRoute
+metadata:
+  name: headers
+spec:
+  parentRefs:
+  - name: gateway
+    sectionName: http
+  hostnames:
+  - "echo.example.com"
+  rules:
+  - matches:
+    - path:
+        type: PathPrefix
+        value: /headers
+    filters:
+    - type: RequestHeaderModifier
+      requestHeaderModifier:
+        set:
+        - name: My-Overwrite-Header
+          value: this-is-the-only-value
+        add:
+        - name: Accept-Encoding
+          value: compress
+        - name:  My-cool-header
+          value: this-is-an-appended-value
+        remove:
+        - User-Agent
+    backendRefs:
+    - name: headers
+      port: 80

examples/http-header-filter/gateway.yaml

@@ -0,0 +1,12 @@
+apiVersion: gateway.networking.k8s.io/v1beta1
+kind: Gateway
+metadata:
+  name: gateway
+  labels:
+    domain: k8s-gateway.nginx.org
+spec:
+  gatewayClassName: nginx
+  listeners:
+  - name: http
+    port: 80
+    protocol: HTTP

examples/http-header-filter/headers.yaml

@@ -0,0 +1,77 @@
+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
+data:
+  nginx.conf: |-
+    user  nginx;
+    worker_processes  1;
+
+    pid        /var/run/nginx.pid;
+
+    load_module /usr/lib/nginx/modules/ngx_http_js_module.so;
+
+    events {}
+
+    http {
+        default_type text/plain;
+
+        js_import /etc/nginx/headers.js;
+        js_set $headers headers.getRequestHeaders;
+
+        server {
+            listen 8080;
+            return 200 "$headers";
+        }
+    }
+  headers.js: |-
+    function getRequestHeaders(r) {
+        let s = "Headers:\n";
+        for (let h in r.headersIn) {
+        s += `  header '${h}' is '${r.headersIn[h]}'\n`;
+        }
+        return s;
+    }
+    export default {getRequestHeaders};
+
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: headers
+spec:
+  ports:
+  - port: 80
+    targetPort: 8080
+    protocol: TCP
+    name: http
+  selector:
+    app: headers

internal/nginx/config/generator.go

@@ -42,5 +42,6 @@ func getExecuteFuncs() []executeFunc {
 		executeUpstreams,
 		executeSplitClients,
 		executeServers,
+		executeMaps,
 	}
 }

internal/nginx/config/http/config.go

@@ -12,12 +12,19 @@ type Server struct {
 
 // Location holds all configuration for an HTTP location.
 type Location struct {
-	Return       *Return
-	Path         string
-	ProxyPass    string
-	HTTPMatchVar string
-	Internal     bool
-	Exact        bool
+	Return          *Return
+	Path            string
+	ProxyPass       string
+	HTTPMatchVar    string
+	ProxySetHeaders []Header
+	Internal        bool
+	Exact           bool
+}
+
+// Header defines a HTTP header to be passed to the proxied server.
+type Header struct {
+	Name  string
+	Value string
 }
 
 // Return represents an HTTP return.
@@ -66,3 +73,16 @@ type SplitClientDistribution struct {
 	Percent string
 	Value   string
 }
+
+// Map defines an NGINX map.
+type Map struct {
+	Source     string
+	Variable   string
+	Parameters []MapParameter
+}
+
+// Parameter defines a Value and Result pair in a Map.
+type MapParameter struct {
+	Value  string
+	Result string
+}

internal/nginx/config/maps.go

@@ -0,0 +1,72 @@
+package config
+
+import (
+	"strings"
+	gotemplate "text/template"
+
+	"github.com/nginxinc/nginx-kubernetes-gateway/internal/nginx/config/http"
+	"github.com/nginxinc/nginx-kubernetes-gateway/internal/state/dataplane"
+)
+
+var mapsTemplate = gotemplate.Must(gotemplate.New("maps").Parse(mapsTemplateText))
+
+func executeMaps(conf dataplane.Configuration) []byte {
+	maps := createMaps(append(conf.HTTPServers, conf.SSLServers...))
+	return execute(mapsTemplate, maps)
+}
+
+func createMaps(servers []dataplane.VirtualServer) []http.Map {
+	return buildAddHeaderMaps(servers)
+}
+
+func buildAddHeaderMaps(servers []dataplane.VirtualServer) []http.Map {
+	addHeaderNames := make(map[string]struct{})
+
+	for _, s := range servers {
+		for _, pr := range s.PathRules {
+			for _, mr := range pr.MatchRules {
+				if mr.Filters.RequestHeaderModifiers != nil {
+					for _, addHeader := range mr.Filters.RequestHeaderModifiers.Add {
+						lowerName := strings.ToLower(addHeader.Name)
+						if _, ok := addHeaderNames[lowerName]; !ok {
+							addHeaderNames[lowerName] = struct{}{}
+						}
+					}
+				}
+			}
+		}
+	}
+
+	maps := make([]http.Map, 0, len(addHeaderNames))
+	for m := range addHeaderNames {
+		maps = append(maps, createAddHeadersMap(m))
+	}
+	return maps
+}
+
+const (
+	// In order to prepend any passed client header values to values specified in the add headers field of request
+	// header modifiers, we need to create a map parameter regex for any string value
+	anyStringFmt = `~.*`
+)
+
+func createAddHeadersMap(name string) http.Map {
+	underscoreName := convertStringToSafeVariableName(name)
+	httpVarSource := "${http_" + underscoreName + "}"
+	mapVarName := generateAddHeaderMapVariableName(name)
+	params := []http.MapParameter{
+		{
+			Value:  "default",
+			Result: "''",
+		},
+		{
+			Value:  anyStringFmt,
+			Result: httpVarSource + ",",
+		},
+	}
+	return http.Map{
+		Source:     httpVarSource,
+		Variable:   "$" + mapVarName,
+		Parameters: params,
+	}
+}

internal/nginx/config/maps_template.go

@@ -0,0 +1,11 @@
+package config
+
+var mapsTemplateText = `
+{{ range $m := . }}
+map {{ $m.Source }} {{ $m.Variable }} {
+    {{ range $p := $m.Parameters }}
+    {{ $p.Value }} {{ $p.Result }};
+    {{ end }}
+}
+{{- end }}
+`