Reverse Proxy

To create a reverse proxy program in Go, follow these steps:

Step 1: Initialize the Go Module

First, create a new directory for your project and initialize the Go module.

mkdir reverseproxy
cd reverseproxy
go mod init github.com/username/reverseproxy

Step 2: Install Dependencies

You will need the gorilla/mux library for routing.

go get github.com/gorilla/mux

Step 3: Create the `reverseproxy.go` File

Create a lib/reverseproxy.go file to handle the reverse proxy functionality.

// reverseproxy.go
package lib

import (
	"log"
	"net/http"
	"net/http/httputil"
	"net/url"

	"github.com/gorilla/mux"
)

type Proxy struct {
	target *url.URL
	proxy  *httputil.ReverseProxy
}

func NewProxy(target string) *Proxy {
	url, _ := url.Parse(target)
	return &Proxy{target: url, proxy: httputil.NewSingleHostReverseProxy(url)}
}

func (p *Proxy) handle(w http.ResponseWriter, r *http.Request) {
	r.URL.Host = p.target.Host
	r.URL.Scheme = p.target.Scheme
	r.Header.Set("X-Forwarded-Host", r.Header.Get("Host"))
	r.Host = p.target.Host
	p.proxy.ServeHTTP(w, r)
}

func Start() {
	target := "http://localhost:8081" // Target server
	proxy := NewProxy(target)

	r := mux.NewRouter()
	r.PathPrefix("/").HandlerFunc(proxy.handle)

	log.Println("Starting reverse proxy on :8080")
	log.Fatal(http.ListenAndServe(":8080", r))
}

Step 4: Create the `main.go` File

Create a main.go file to start the reverse proxy.

// main.go
package main

import "github.com/username/reverseproxy/lib"

func main() {
    lib.Start()
}

Step 5: Run the Program

Run the program using the go run command.

go run main.go

This will start the reverse proxy on port 8080, forwarding requests to the target server specified in the target variable.

Last modified: 08 January 2025