upstream cluster {
    server 192.168.0.14;
    server 192.168.0.15;
}

location / {
   proxy_set_header X-Real-IP $remote_addr;               //返回真實IP
   proxy_pass http://cluster;                           //代理指向cluster 
    
}

type RoundRobinBalance struct {
    curIndex int
    rss []string
}

/**
 * @Author: yang
 * @Description：添加服務
 * @Date: 2021/4/7 15:36
 */
func (r *RoundRobinBalance) Add (params ...string) error{
    if len(params) == 0 {
        return errors.New("params len 1 at least")
    }
    addr := params[0]
    r.rss = append(r.rss, addr)

    return nil
}

/**
 * @Author: yang
 * @Description：輪詢獲取服務
 * @Date: 2021/4/7 15:36
 */
func (r *RoundRobinBalance) Next () string {
    if len(r.rss) == 0 {
        return ""
    }
    lens := len(r.rss)
    if r.curIndex >= lens {
        r.curIndex = 0
    }
    curAdd := r.rss[r.curIndex ]
    r.curIndex = (r.curIndex + 1) % lens
    return curAdd
}

/**
 * @Author: yang
 * @Description：測試
 * @Date: 2021/4/7 15:36
 */
func main(){
    rb := new(RoundRobinBalance)
    rb.Add("127.0.0.1:80")
    rb.Add("127.0.0.1:81")
    rb.Add("127.0.0.1:82")
    rb.Add("127.0.0.1:83")

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

go run main.go 

127.0.0.1:80
127.0.0.1:81
127.0.0.1:82
127.0.0.1:83
127.0.0.1:80
127.0.0.1:81

http {  
    upstream cluster {  
        server 192.168.1.2 weight=5;  
        server 192.168.1.3 weight=3;  
        server 192.168.1.4 weight=1;  
    }  

location / {
       proxy_set_header X-Real-IP $remote_addr;               //返回真實IP
       proxy_pass http://cluster;                           //代理指向cluster 
   }

type WeightRoundRobinBalance struct {
    curIndex int
    rss []*WeightNode
}

type WeightNode struct {
    weight int // 配置的權重，即在配置文件或初始化時約定好的每個節(jié)點的權重
    currentWeight int //節(jié)點當前權重，會一直變化
    effectiveWeight int //有效權重，初始值為weight, 通訊過程中發(fā)現(xiàn)節(jié)點異常，則-1 ，之后再次選取本節(jié)點，調用成功一次則+1，直達恢復到weight 。 用于健康檢查，處理異常節(jié)點，降低其權重。
    addr string // 服務器addr
}

/**
 * @Author: yang
 * @Description：添加服務
 * @Date: 2021/4/7 15:36
 */
func (r *WeightRoundRobinBalance) Add (params ...string) error{
    if len(params) != 2{
        return errors.New("params len need 2")
    }
    // @Todo 獲取值
    addr := params[0]
    parInt, err  := strconv.ParseInt(params[1], 10, 64)
    if err != nil {
        return err
    }
    node := &WeightNode{
        weight: int(parInt),
        effectiveWeight: int(parInt),  // 初始化時有效權重 = 配置權重值
        currentWeight: int(parInt), // 初始化時當前權重 = 配置權重值
        addr: addr,
    }
    r.rss = append(r.rss, node)
    return nil
}

/**
 * @Author: yang
 * @Description：輪詢獲取服務
 * @Date: 2021/4/7 15:36
 */
func (r *WeightRoundRobinBalance) Next () string {
    // @Todo 沒有服務
    if len(r.rss) == 0 {
        return ""
    }

    totalWeight := 0
    var maxWeightNode *WeightNode
    for key , node  := range r.rss {
        // @Todo 計算當前狀態(tài)下所有節(jié)點的effectiveWeight之和totalWeight
        totalWeight += node.effectiveWeight

        // @Todo 計算currentWeight
        node.currentWeight += node.effectiveWeight

        // @Todo 尋找權重最大的
        if maxWeightNode == nil ||  maxWeightNode.currentWeight < node.currentWeight {
            maxWeightNode = node
            r.curIndex = key
        }
    }

    // @Todo 更新選中節(jié)點的currentWeight
    maxWeightNode.currentWeight -= totalWeight

    // @Todo 返回addr
    return maxWeightNode.addr
}

/**
 * @Author: yang
 * @Description：測試
 * @Date: 2021/4/7 15:36
 */
func main(){
    rb := new(WeightRoundRobinBalance)
    rb.Add("127.0.0.1:80", "4")
    rb.Add("127.0.0.1:81", "2")
    rb.Add("127.0.0.1:82", "1")

    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())
}