12 factor HTTP proxy

main.go

package main

import (
	"log"
	"net/http"
	"net/http/httputil"
	"net/url"
	"os"
	"time"
)

func main() {
	var src, dst string

	dst = os.Getenv("DESTINATION")
	src = ":" + os.Getenv("PORT")

	u, e := url.Parse(dst)
	if e != nil {
		log.Fatal("Bad destination.")
	}
	h := httputil.NewSingleHostReverseProxy(u)
	s := &http.Server{
		Addr:           src,
		Handler:        h,
		ReadTimeout:    10 * time.Second,
		WriteTimeout:   10 * time.Second,
		MaxHeaderBytes: 1 << 20,
	}
	log.Fatal(s.ListenAndServe())
}