golang实现反向代理，负载均衡

反向代理以及负载均衡算法知识：

https://www.cnblogs.com/sunlong88/p/13512362.html

多层代理实现：

实现一个多层代理

一层代理 go run ichunt_micro_service/test/reverseProxy/one/oneAgent.go

二层代理 go run ichunt_micro_service/test/reverseProxy/two/twoAgent.go

真实ip go run ichunt_micro_service/test/reverseProxy/realServer.go

代理实现

func main() {
    rs1 := "http://127.0.0.1:2002"
    url1, err1 := url.Parse(rs1)
    if err1 != nil {
        log.Println(err1)
    }
    urls := []*url.URL{url1}
    proxy := NewMultipleHostsReverseProxy(urls)
    log.Println("Starting httpserver at " + addr)
    log.Fatal(http.ListenAndServe(addr, proxy))
}

var transport = &http.Transport{
    DialContext: (&net.Dialer{
        Timeout:   30 * time.Second, //连接超时
        KeepAlive: 30 * time.Second, //长连接超时时间
    }).DialContext,
    MaxIdleConns:          100,              //最大空闲连接
    IdleConnTimeout:       90 * time.Second, //空闲超时时间
    TLSHandshakeTimeout:   10 * time.Second, //tls握手超时时间
    ExpectContinueTimeout: 1 * time.Second,  //100-continue 超时时间
}


func NewMultipleHostsReverseProxy(targets []*url.URL) *httputil.ReverseProxy {
    //请求协调者
    director := func(req *http.Request) {
        //url_rewrite
        //127.0.0.1:2002/dir/abc ==> 127.0.0.1:2003/base/abc ??
        //127.0.0.1:2002/dir/abc ==> 127.0.0.1:2002/abc
        //127.0.0.1:2002/abc ==> 127.0.0.1:2003/base/abc
        re, _ := regexp.Compile("^/dir(.*)");
        req.URL.Path = re.ReplaceAllString(req.URL.Path, "$1")

        //随机负载均衡
        targetIndex := rand.Intn(len(targets))
        target := targets[targetIndex]
        targetQuery := target.RawQuery
        req.URL.Scheme = target.Scheme
        req.URL.Host = target.Host

        // url地址重写：重写前：/aa 重写后：/base/aa
        req.URL.Path = singleJoiningSlash(target.Path, req.URL.Path)
        if targetQuery == "" || req.URL.RawQuery == "" {
            req.URL.RawQuery = targetQuery + req.URL.RawQuery
        } else {
            req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
        }
        if _, ok := req.Header["User-Agent"]; !ok {
            req.Header.Set("User-Agent", "user-agent")
        }
        //只在第一代理中设置此header头
        req.Header.Set("X-Real-Ip", req.RemoteAddr)
    }
    //更改内容
    modifyFunc := func(resp *http.Response) error {
        //请求以下命令：curl 'http://127.0.0.1:2002/error'
        if resp.StatusCode != 200 {
            //获取内容
            oldPayload, err := ioutil.ReadAll(resp.Body)
            if err != nil {
                return err
            }
            //追加内容
            newPayload := []byte("StatusCode error:" + string(oldPayload))
            resp.Body = ioutil.NopCloser(bytes.NewBuffer(newPayload))
            resp.ContentLength = int64(len(newPayload))
            resp.Header.Set("Content-Length", strconv.FormatInt(int64(len(newPayload)), 10))
        }
        return nil
    }
    //错误回调 ：关闭real_server时测试，错误回调
    errFunc := func(w http.ResponseWriter, r *http.Request, err error) {
        http.Error(w, "ErrorHandler error:"+err.Error(), 500)
    }
    return &httputil.ReverseProxy{
        Director:       director,
        Transport:      transport,
        ModifyResponse: modifyFunc,
        ErrorHandler:   errFunc}
}

func singleJoiningSlash(a, b string) string {
    aslash := strings.HasSuffix(a, "/")
    bslash := strings.HasPrefix(b, "/")
    switch {
    case aslash && bslash:
        return a + b[1:]
    case !aslash && !bslash:
        return a + "/" + b
    }
    return a + b
}

反向代理，通过负载均衡获取服务地址

运行实际服务 127.0.0.1:2003 127.0.0.1:2004

go run ichunt_micro_service/test/reverseProxy/realServer.go

启动反向代理：内置负载均衡器 go run ichunt_micro_service/test/load_balance/main.go

//负载均衡获取服务地址 load_balance.LoadBanlanceFactory(load_balance.LbWeightRoundRobin)

func main() {
    rb := load_balance.LoadBanlanceFactory(load_balance.LbWeightRoundRobin)
    if err := rb.Add("http://127.0.0.1:2003/", "10"); err != nil {
        log.Println(err)
    }
    if err := rb.Add("http://127.0.0.1:2004/", "20"); err != nil {
        log.Println(err)
    }
    proxy := NewMultipleHostsReverseProxy(rb)
    log.Println("Starting httpserver at " + addr)
    log.Fatal(http.ListenAndServe(addr, proxy))
}

内置几种负载均衡算法：

hash算法 基于url和ip地址的hash

package load_balance

import (
    "fmt"
    "testing"
)

func TestNewConsistentHashBanlance(t *testing.T) {
    rb := NewConsistentHashBanlance(10, nil)
    rb.Add("127.0.0.1:2003") //0
    rb.Add("127.0.0.1:2004") //1
    rb.Add("127.0.0.1:2005") //2
    rb.Add("127.0.0.1:2006") //3
    rb.Add("127.0.0.1:2007") //4

    //url hash
    fmt.Println(rb.Get("http://127.0.0.1:2002/base/getinfo"))
    fmt.Println(rb.Get("http://127.0.0.1:2002/base/error"))
    fmt.Println(rb.Get("http://127.0.0.1:2002/base/getinfo"))
    fmt.Println(rb.Get("http://127.0.0.1:2002/base/changepwd"))

    //ip hash
    fmt.Println(rb.Get("127.0.0.1"))
    fmt.Println(rb.Get("192.168.0.1"))
    fmt.Println(rb.Get("127.0.0.1"))
}

随机算法

package load_balance

import (
    "fmt"
    "testing"
)

func TestRandomBalance(t *testing.T) {
    rb := &RandomBalance{}
    rb.Add("127.0.0.1:2003") //0
    rb.Add("127.0.0.1:2004") //1
    rb.Add("127.0.0.1:2005") //2
    rb.Add("127.0.0.1:2006") //3
    rb.Add("127.0.0.1:2007") //4

    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
}

轮询算法：

package load_balance

import (
    "fmt"
    "testing"
)

func Test_main(t *testing.T) {
    rb := &RoundRobinBalance{}
    rb.Add("127.0.0.1:2003") //0
    rb.Add("127.0.0.1:2004") //1
    rb.Add("127.0.0.1:2005") //2
    rb.Add("127.0.0.1:2006") //3
    rb.Add("127.0.0.1:2007") //4

    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
}

加权轮询算法：

package load_balance

import (
    "fmt"
    "testing"
)

func TestLB(t *testing.T) {
    rb := &WeightRoundRobinBalance{}
    rb.Add("127.0.0.1:2003", "4") //0
    rb.Add("127.0.0.1:2004", "3") //1
    rb.Add("127.0.0.1:2005", "2") //2

    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
    fmt.Println(rb.Next())
}

项目代码：

https://github.com/sunlongv520/golang-loadbalance-reverseproxy