HTTP reverse proxy that uses Redis for vhost routing.

proxy.go

// HTTP reverse proxy that uses Redis for vhost routing.
//
// ADDR=:8080 REDIS=127.0.0.1:6379 go run proxy.go
// redis-cli set localhost:8080 http://sports.yahoo.com
// curl -v localhost:8080

package main

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

	"github.com/fiorix/go-redis/redis"
)

func main() {
	http.HandleFunc("/", ProxyHandler)
	http.ListenAndServe(os.Getenv("ADDR"), nil)
}

var rc = redis.New(os.Getenv("REDIS"))
var err503 = errors.New(http.StatusText(http.StatusServiceUnavailable))

func ProxyHandler(w http.ResponseWriter, r *http.Request) {
	u, err := getURL(r)
	if err != nil {
		http.Error(w, err.Error(), http.StatusServiceUnavailable)
		return
	}
	r.Host = u.Host
	st := time.Now()
	httputil.NewSingleHostReverseProxy(u).ServeHTTP(w, r)
	log.Printf("Proxied %s%s for %s in %s",
		u, r.URL.Path, r.RemoteAddr, time.Since(st),
	)
}

func getURL(r *http.Request) (*url.URL, error) {
	targetURL, err := rc.Get(r.Host)
	if err != nil {
		return nil, err
	}
	if len(targetURL) == 0 {
		return nil, err503
	}
	return url.Parse(targetURL)
}