# Nginx 负载均衡

![](https://kingofzihua.oss-cn-shanghai.aliyuncs.com/blog/nginx/load-balancing-nginx.png)

## 配置语法

| upstream |                     |
| -------- | ------------------- |
| 语法       | upstream name {...} |
| 默认       | ---                 |
| 作用域      | http                |

## 后段服务器在负载调度中的状态

| 状态            | 介绍                      |
| ------------- | ----------------------- |
| down          | 当前的server暂时不参与负载均衡      |
| backup        | 预留的备份服务器                |
| max\_fails    | 允许请求失败的次数               |
| fail\_timeout | 经过max\_fails失败后,服务暂停的时间 |
| max\_conns    | 限制最大的接受连接数              |

### 例子:

```
        ...
    # 在http里面
    upstream test{
        server 192.168.10.10:8001;

        # weight : 负载权重
        server 192.168.10.10:8002 weight=5;

        # backup : 表示这个是一个备份节点
        server 192.168.10.10:8003 backup; 

        # down : 表示这个节点不参与服务
        server 192.168.10.10:8004 down;

        # max_fails : 允许请求失败的次数 fail_timeout : 经过max_fails失败后,服务暂停的时间
        server 192.168.10.10:8005 max_fails=1 fail_timeout=10s;

        # unix : socket方式
        #server unix:/tmp/backend3; 
    }

    server {
        ....

        location / {
            # test是上面定义的upstream 的名字
            proxy_pass http://test
            proxy_redirect default; #302跳转的时候，默认

            ...

        }

        ...
    }
```


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