golang简单http反向代理

类似nginx的反向代理，将8081端口请求代理到后端服务8001 8002 和 8003
轮训方式，无负载均衡服务发现等

package main

import (
    "fmt"
    "log"
    "net/http"
    "net/http/httputil"
    "net/url"
    "sync/atomic"
)

var backendServiceCount = 3

/**
后端服务组
*/
var backendServiceList = make([]*httputil.ReverseProxy, backendServiceCount)

var index int64 = 0

func init() {
    for i := 0; i < backendServiceCount; i++ {
        url, _ := url.Parse(fmt.Sprintf("http://127.0.0.1:%d", (8001 + i)))
        log.Println("初始化后端服务", url)
        proxy := httputil.NewSingleHostReverseProxy(url)
        backendServiceList[i] = proxy
    }
}

/**
反向代理给后端服务
*/
func rproxy(w http.ResponseWriter, r *http.Request) {
    //轮训方式选择一个后端服务
    i := atomic.AddInt64(&index, 1)
    proxy := backendServiceList[i%int64(backendServiceCount)]
    proxy.ServeHTTP(w, r)
}

/**
反向代理
将8081端口请求代理到后端服务8001 8002 和 8003
*/
func main() {
    http.HandleFunc("/", rproxy)
    log.Fatal(http.ListenAndServe(":8000", nil))
}