ingress proxy_header

Ingress Proxy Header Explained

In the world of web development, proxy servers play a crucial role in handling and forwarding client requests to backend servers. Proxy servers act as intermediaries, enhancing security, performance, and scalability. One popular tool used for managing proxy servers is Ingress, which is built on top of Kubernetes.

In this article, we will explore the "ingress proxy_header" configuration option in Ingress. We will explain what it does, why it is important, and provide some code examples to demonstrate its usage.

Understanding Ingress Proxy Header

When a client sends a request to a web server, it includes various headers that provide additional information about the request. These headers can include details such as the client's IP address, user agent, and cookies. However, when a request goes through a proxy server, the original headers might get modified or replaced with new ones.

Ingress Proxy Header is a configuration option that allows you to specify which headers should be trusted and preserved when requests pass through an Ingress Controller. By default, Ingress does not propagate certain headers like "X-Forwarded-For" or "X-Real-IP". However, in some cases, it is essential to access the original client headers for authentication, logging, or other purposes. That's where "ingress proxy_header" comes into play.

Configuring Ingress Proxy Header

To configure Ingress Proxy Header, you need to modify your Ingress resource definition in Kubernetes. Here's an example using YAML syntax:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: my-ingress
spec:
  rules:
    - host: example.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: my-service
                port:
                  number: 80
  metadata:
    annotations:
      nginx.ingress.kubernetes.io/proxy-body-size: 20m
      nginx.ingress.kubernetes.io/proxy-buffer-size: 8k
      nginx.ingress.kubernetes.io/proxy-header: "X-Real-IP $proxy_add_x_forwarded_for"

In the above example, we have added the "nginx.ingress.kubernetes.io/proxy-header" annotation with a value of "X-Real-IP $proxy_add_x_forwarded_for". This configuration tells the Ingress Controller to trust and preserve the "X-Real-IP" header and append the "X-Forwarded-For" header to it.

Code Example: Go Application

Let's consider a simple Go application that needs to access the client's IP address. Without configuring Ingress Proxy Header, the application would only see the IP address of the Ingress Controller.

package main

import (
	"fmt"
	"net/http"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		ip := r.RemoteAddr
		fmt.Fprintf(w, "Your IP address is: %s", ip)
	})

	http.ListenAndServe(":8080", nil)
}

However, by configuring Ingress Proxy Header, we can access the original client IP address. Here's an updated version of the Go application that works with Ingress Proxy Header:

package main

import (
	"fmt"
	"net/http"
)

func main() {
	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		ip := r.Header.Get("X-Real-IP")
		fmt.Fprintf(w, "Your IP address is: %s", ip)
	})

	http.ListenAndServe(":8080", nil)
}

With the updated code, our Go application can now retrieve the client's IP address from the "X-Real-IP" header, which is preserved by the Ingress Controller.

Conclusion

Ingress Proxy Header is a valuable configuration option in Ingress that allows you to preserve and access client headers when requests pass through a proxy server. By configuring this option, you can ensure that your backend services have access to important information like the client's IP address. This can be crucial for security, logging, and other purposes.

Remember to properly configure the Ingress Controller and annotate your Ingress resources to specify which headers should be trusted and preserved. This will ensure that your application can make use of the original client headers.

In this article, we explored the "ingress proxy_header" configuration option, provided code examples, and discussed its importance in web development. By understanding and utilizing this configuration, you can enhance the functionality and security of your applications.