Allow overriding real_ip_recursive

docs/user-guide/nginx-configuration/configmap.md

@@ -929,6 +929,10 @@ If false, NGINX ignores incoming `X-Forwarded-*` headers, filling them with the
 
 `enable-real-ip` enables the configuration of [https://nginx.org/en/docs/http/ngx_http_realip_module.html](https://nginx.org/en/docs/http/ngx_http_realip_module.html). Specific attributes of the module can be configured further by using `forwarded-for-header` and `proxy-real-ip-cidr` settings.
 
+## enable-real-ip-recursive
+
+`enable-real-ip-recursive` enables the configuration of [https://nginx.org/en/docs/http/ngx_http_realip_module.html#real_ip_recursive](https://nginx.org/en/docs/http/ngx_http_realip_module.html#real_ip_recursive).
+
 ## forwarded-for-header
 
 Sets the header field for identifying the originating IP address of a client. _**default:**_ X-Forwarded-For

internal/ingress/controller/config/config.go

@@ -556,6 +556,11 @@ type Configuration struct {
 	// Sets whether to enable the real ip module
 	EnableRealIP bool `json:"enable-real-ip"`
 
+	// Sets whether to use recursive search in the real ip module
+	// https://nginx.org/en/docs/http/ngx_http_realip_module.html#real_ip_recursive
+	// Default: true
+	EnableRealIPRecursive bool `json:"enable-real-ip-recursive"`
+
 	// Sets the header field for identifying the originating IP address of a client
 	// Default is X-Forwarded-For
 	ForwardedForHeader string `json:"forwarded-for-header,omitempty"`
@@ -790,6 +795,7 @@ func NewDefault() Configuration {
 		ErrorLogLevel:                    errorLevel,
 		UseForwardedHeaders:              false,
 		EnableRealIP:                     false,
+		EnableRealIPRecursive:            false,
 		ForwardedForHeader:               "X-Forwarded-For",
 		ComputeFullForwardedFor:          false,
 		ProxyAddOriginalURIHeader:        false,

rootfs/etc/nginx/template/nginx.tmpl

@@ -143,7 +143,12 @@ http {
     real_ip_header      {{ $cfg.ForwardedForHeader }};
     {{ end }}
 
+    {{ if $cfg.EnableRealIPRecursive }}
     real_ip_recursive   on;
+    {{ else }}
+    real_ip_recursive   off;
+    {{ end }}
+
     {{ range $trusted_ip := $cfg.ProxyRealIPCIDR }}
     set_real_ip_from    {{ $trusted_ip }};
     {{ end }}

test/e2e/settings/enable_real_ip_recursive.go

@@ -0,0 +1,102 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package settings
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/onsi/ginkgo"
+	"github.com/stretchr/testify/assert"
+
+	"k8s.io/ingress-nginx/test/e2e/framework"
+)
+
+const forwardedForHost = "forwarded-for-header"
+
+var _ = framework.DescribeSetting("enable-real-ip-recursive", func() {
+	f := framework.NewDefaultFramework("enable-real-ip-recursive")
+
+	setting := "enable-real-ip-recursive"
+
+	ginkgo.BeforeEach(func() {
+		f.NewEchoDeployment()
+
+		f.SetNginxConfigMapData(map[string]string{
+			"log-format-escape-json": "true",
+			"log-format-upstream":    "clientip=\"$remote_addr\"",
+			"use-forwarded-headers":  "true",
+			setting:                  "false",
+		})
+	})
+
+	ginkgo.It("should use the first IP in X-Forwarded-For header when setting is true", func() {
+		host := forwardedForHost
+
+		f.UpdateNginxConfigMapData(setting, "true")
+
+		ing := framework.NewSingleIngress(host, "/", host, f.Namespace, framework.EchoService, 80, nil)
+		f.EnsureIngress(ing)
+
+		f.WaitForNginxConfiguration(func(conf string) bool {
+			return strings.Contains(conf, "real_ip_recursive on;")
+		})
+
+		ginkgo.By("ensuring single values are parsed correctly")
+		body := f.HTTPTestClient().
+			GET("/").
+			WithHeader("Host", host).
+			WithHeader("X-Forwarded-For", "127.0.0.1, 1.2.3.4").
+			Expect().
+			Status(http.StatusOK).
+			Body().
+			Raw()
+
+		assert.Contains(ginkgo.GinkgoT(), body, "x-forwarded-for=127.0.0.1")
+
+		logs, err := f.NginxLogs()
+		assert.Nil(ginkgo.GinkgoT(), err, "obtaining nginx logs")
+		assert.Contains(ginkgo.GinkgoT(), logs, "clientip=\"127.0.0.1\"")
+	})
+
+	ginkgo.It("should use the last IP in X-Forwarded-For header when setting is false", func() {
+		host := forwardedForHost
+
+		f.UpdateNginxConfigMapData(setting, "false")
+
+		f.EnsureIngress(framework.NewSingleIngress(host, "/", host, f.Namespace, framework.EchoService, 80, nil))
+
+		f.WaitForNginxConfiguration(func(conf string) bool {
+			return strings.Contains(conf, "real_ip_recursive off;")
+		})
+
+		body := f.HTTPTestClient().
+			GET("/").
+			WithHeader("Host", host).
+			WithHeader("X-Forwarded-For", "127.0.0.1, 1.2.3.4").
+			Expect().
+			Status(http.StatusOK).
+			Body().
+			Raw()
+
+		assert.Contains(ginkgo.GinkgoT(), body, "x-forwarded-for=1.2.3.4")
+
+		logs, err := f.NginxLogs()
+		assert.Nil(ginkgo.GinkgoT(), err, "obtaining nginx logs")
+		assert.Contains(ginkgo.GinkgoT(), logs, "clientip=\"1.2.3.4\"")
+	})
+})