服务治理【2】HTTP流量转发及负载均衡

桃扇骨 2022-04-17 00:22 223阅读 0赞

# 一、启动后端服务器 #

> 代码在这篇[《文章》][Link 1]中第一节

# 二、反向代理模块 #

`utils/httputil.go`( 拼接url输出正确的url )

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
    }

`proxy/lbalance/factory.go`( 加载负载策略 )

type LbType int
    const (
    	LbRandom = iota
    	LbRoundRobin
    )
    type LoadBalance interface { 
    	Add(params ...string) error
    	Next() string
    	Get(key string) (string, error)
    }
    func LoadBalanceFactory(lbtype LbType) LoadBalance { 
    	switch lbtype { 
    	case LbRandom:
    		return &RandomBalance{ }
    	case LbRoundRobin:
    		return &RoundRobinBalance{ }
    	default:
    		return &RandomBalance{ }
    	}
    }

`proxy/lbalance/random.go`( 随机负载模块 )

type RandomBalance struct { 
    	curIndex int
    	rss      []string
    }
    func (r *RandomBalance) Add(params ...string) error { 
    	if len(params) == 0 { 
    		return errors.New("param len 1 at least")
    	}
    	r.rss = append(r.rss, params[0])
    	return nil
    }
    func (r *RandomBalance) Next() string { 
    	if len(r.rss) == 0 { 
    		return ""
    	}
    	r.curIndex = rand.Intn(len(r.rss))
    	return r.rss[r.curIndex]
    }
    func (r *RandomBalance) Get(key string) (string, error) { 
    	return r.Next(), nil
    }

`proxy/lbalance/round_robin.go`( 轮询负载模块 )

type RoundRobinBalance struct { 
    	curIndex int
    	rss      []string
    }
    func (r *RoundRobinBalance) Add(params ...string) error { 
    	if len(params) == 0 { 
    		return errors.New("param len 1 at least")
    	}
    	r.rss = append(r.rss, params[0])
    	return nil
    }
    func (r *RoundRobinBalance) Next() string { 
    	if len(r.rss) == 0 { 
    		return ""
    	}
    	length := len(r.rss)
    	if r.curIndex >= length { 
    		r.curIndex = 0
    	}
    	curAddr := r.rss[r.curIndex]
    	r.curIndex = r.curIndex + 1
    	return curAddr
    }
    func (r *RoundRobinBalance) Get(key string) (string, error) { 
    	return r.Next(), nil
    }

`proxy/server/server.go`( 代理服务器，处理上下游请求和返回体 )

type Proxy struct { 
    	lb lbalance.LoadBalance
    }
    func (p *Proxy) director(req *http.Request) { 
    	hitUrl, err := p.lb.Get(req.URL.Path)
    	log.Println("nextAddr: ", hitUrl)
    	if err != nil { 
    		log.Fatal(err)
    	}
    	target, err := url.Parse(hitUrl)
    	if err != nil { 
    		log.Fatal(err)
    	}
    	targetQuery := target.RawQuery
    	req.URL.Scheme = target.Scheme
    	req.URL.Host = target.Host
    	req.URL.Path = utils.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 { 
    		// explicitly disable User-Agent so it's not set to default value
    		req.Header.Set("User-Agent", "")
    	}
    }
    func (p *Proxy) modifyResponse(res *http.Response) error { 
    	if res.StatusCode == 500 { 
    		data, _ := ioutil.ReadAll(res.Body)
    		data = []byte("jstang " + string(data))
    		res.ContentLength = int64(len(data))
    		res.Header.Set("Content-Length", fmt.Sprint(len(data)))
    		res.Body = ioutil.NopCloser(bytes.NewBuffer(data))
    	}
    	return nil
    }
    func (p *Proxy) NewMultiHostReverseProxy(lb lbalance.LoadBalance) (*httputil.ReverseProxy, error) { 
    	p.lb = lb
    	reverse := &httputil.ReverseProxy{ 
    		Director:       p.director,
    		ModifyResponse: p.modifyResponse,
    	}
    	return reverse, nil
    }

# 三、构建并使用流量转发中间件\*\* #

`middleware/proxy_pass.go`

package main
    import (
    	"demo/middleware"
    	"demo/proxy/lbalance"
    	"demo/proxy/server"
    	"log"
    	"net/http"
    )
    var (
    	gateway string = "172.*.*.249:10000"
    	real1   string = "http://172.*.*.249:8888"
    	real2   string = "http://172.*.*.249:6666/append"
    )
    func main() { 
    	// 构建反向代理
    	lb := lbalance.LoadBalanceFactory(lbalance.LbRoundRobin)
    	if err := lb.Add(real1, "10"); err != nil { 
    		log.Fatal(err)
    	}
    	if err := lb.Add(real2, "20"); err != nil { 
    		log.Fatal(err)
    	}
    	proxy := &server.Proxy{ }
    	reverse, err := proxy.NewMultiHostReverseProxy(lb)
    	if err != nil { 
    		log.Fatal(err)
    	}
    
    	// 构建路由
    	router := middleware.NewSliceRouter()
    	router.Group("/gateway").Use(middleware.TraceLogSliceMW(), func(c *middleware.SliceRouterContext) { 
    		c.Rw.WriteHeader(http.StatusForbidden)
    		c.Rw.Write([]byte(http.StatusText(http.StatusForbidden)))
    	})
    	router.Group("/").Use(middleware.TraceLogSliceMW(), func(c *middleware.SliceRouterContext) { 
    		log.Println("Transport Forward To Backend...")
    		reverse.ServeHTTP(c.Rw, c.Req)
    	})
    	handler := middleware.NewSliceRouterHandler(nil, router)
    	log.Println("Gateway start at: ", gateway)
    	log.Fatal(http.ListenAndServe(gateway, handler))
    }

# 四、代码结构和运行结果 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4OTAwNTY1_size_16_color_FFFFFF_t_70_pic_center]

[Link 1]: https://blog.csdn.net/qq_38900565/article/details/104690103
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM4OTAwNTY1_size_16_color_FFFFFF_t_70_pic_center]: /images/20220417/cae28c13a22b4517af14bc6117667b5b.png