20190716 Nginx多种负载均衡策略搭建

缺乏、安全感 2021-12-09 07:47 179阅读 0赞

## 背景介绍 ##

本文详细讲述Nginx下的几种负载均衡策略。

upstream backend {
        server himitsu.no.site:443;
    }
    
    server {
    
      ...
    
      location / {
        proxy_pass https://backend/;
      }
    
      ...
    }

## 轮询 ##

轮询，顾名思义，就是轮流请求，我们将负载均衡策略聚焦于`default.conf`文件的`upstream`。

*  在轮询中，如果服务器down掉了，会自动剔除该服务器。
 *  缺省配置就是轮询策略。
 *  此策略适合服务器配置相当，无状态且短平快的服务使用。

upstream backend {
        server web02:80;
        server web03:80;
    }

在浏览器中对`localhost:8080`连续发出请求，根据nginx请求日志可以看出web02与web03访问的次数是相同的。

web01    | 172.24.0.1 - - [26/Jun/2019:10:03:06 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:10:03:06 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:10:03:07 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.3 - - [26/Jun/2019:10:03:07 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:10:05:25 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:10:05:25 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.3 - - [26/Jun/2019:10:05:26 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:10:05:26 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.3 - - [26/Jun/2019:10:05:27 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

## 加权轮询 ##

加权轮询是指基于上文中的轮询，加上一定的权重，使得某个服务器被转发的次数更多一些，加权通过在IP后方拼接weight实现。

*  权重越高分配到需要处理的请求越多。
 *  此策略可以与least\_conn和ip\_hash结合使用。
 *  此策略比较适合服务器的硬件配置差别比较大的情况。

upstream backend {
        server web02:80 weight=5;
        server web03:80 weight=1;
    }

weight值越大，所分配的请求就越多，根据nginx的请求日志可以看出web02被访问了8次，web03被访问了两次。

web01    | 172.24.0.1 - - [26/Jun/2019:14:48:13 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:13 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:16 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.3 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:17 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:18 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:18 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:19 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.3 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.3 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [26/Jun/2019:14:48:20 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

## ip\_hash ##

如果一个客户端的请求可能被转发到任何一台服务器，可能会导致每台服务器都缓存了该客户端的信息，比较浪费资源，ip\_hash作用就是通过客户端IP的前三个部分计算出key，以便将同一个客户端的请求转发到指定的服务器中，配置的方法比较简单，只需要在`upstream`上方加一行代码即可。

*  在nginx版本1.3.1之前，不能在ip\_hash中使用权重（weight）。
 *  ip\_hash不能与backup同时使用。
 *  此策略适合有状态服务，比如session。
 *  当有服务器需要剔除，必须手动down掉。

upstream backend {
        ip_hash;
        server web02:80;
        server web03:80;
    }

重复请求了5次，通过日志看出请求一直被锁定在了web03上。

web01    | 172.24.0.1 - - [27/Jun/2019:11:48:15 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.2 - - [27/Jun/2019:11:48:15 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1"
    web01    | 172.24.0.1 - - [27/Jun/2019:11:48:22 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.2 - - [27/Jun/2019:11:48:22 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1"
    web03    | 172.24.0.2 - - [27/Jun/2019:11:48:23 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1"
    web01    | 172.24.0.1 - - [27/Jun/2019:11:48:23 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.2 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1"
    web01    | 172.24.0.1 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.2 - - [27/Jun/2019:11:48:24 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "172.24.0.1"

## least\_conn ##

把请求转发给连接数较少的后端服务器。轮询算法是把请求平均的转发给各个后端，使它们的负载大致相同；但是，有些请求占用的时间很长，会导致其所在的后端负载较高。这种情况下，least\_conn这种方式就可以达到更好的负载均衡效果，此负载均衡策略适合请求处理时间长短不一造成服务器过载的情况。

#动态服务器组
        upstream dynamic_zuoyu {
            least_conn;    #把请求转发给连接数较少的后端服务器
            server localhost:8080   weight=2;  #tomcat 7.0
            server localhost:8081;  #tomcat 8.0
            server localhost:8082 backup;  #tomcat 8.5
            server localhost:8083   max_fails=3 fail_timeout=20s;  #tomcat 9.0
        }

## url\_hash ##

这种模式是将url进行哈希，然后定位到具体的某一台服务器，相同的url永远会被转发到同一台服务器上。

upstream backend {
        hash $request_uri;
        server web02:80;
        server web03:80;
    }

通过浏览器访问两次`http://localhost:8080`，通过日志可以看到转发被固定在了web03。

web01    | 172.24.0.1 - - [27/Jun/2019:11:58:31 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.4 - - [27/Jun/2019:11:58:31 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web03    | 172.24.0.4 - - [27/Jun/2019:11:58:38 +0000] "GET / HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [27/Jun/2019:11:58:38 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

在链接后面拼接一些参数，就可以看到转发发生了变化，固定在了web02，随着参数的变化，请求也会采用轮询的方式转发给服务器，但使用过的url再访问就不会再变化了。

web02    | 172.24.0.4 - - [27/Jun/2019:11:59:54 +0000] "GET /?a=1 HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [27/Jun/2019:11:59:54 +0000] "GET /?a=1 HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web02    | 172.24.0.4 - - [27/Jun/2019:11:59:55 +0000] "GET /?a=1 HTTP/1.0" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"
    web01    | 172.24.0.1 - - [27/Jun/2019:11:59:55 +0000] "GET /?a=1 HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.169 Safari/537.36" "-"

--------------------

### fair ###

按照服务器端的响应时间来分配请求，响应时间短的优先分配。

#动态服务器组
        upstream dynamic_zuoyu {
            server localhost:8080;  #tomcat 7.0
            server localhost:8081;  #tomcat 8.0
            server localhost:8082;  #tomcat 8.5
            server localhost:8083;  #tomcat 9.0
            fair;    #实现响应时间短的优先分配
        }

**Sticky工作原理 ：**

Sticky是nginx的一个模块，它是基于cookie的一种nginx的负载均衡解决方案，通过分发和识别cookie，来使同一个客户端的请求落在同一台服务器上，默认标识名为route  
1.客户端首次发起访问请求，nginx接收后，发现请求头没有cookie，则以轮询方式将请求分发给后端服务器。  
2.后端服务器处理完请求，将响应数据返回给nginx。  
3.此时nginx生成带route的cookie，返回给客户端。route的值与后端服务器对应，可能是明文，也可能是md5、sha1等Hash值  
4.客户端接收请求，并保存带route的cookie。  
5.当客户端下一次发送请求时，会带上route，nginx根据接收到的cookie中的route值，转发给对应的后端服务器。

http {
    #OK include vhost/xxx.conf;
    upstream shop_server{
    sticky;
    #Sticky是nginx的一个模块，它是基于cookie的一种nginx的负载均衡解决方案，通过分发和识别cookie，来使同一个客户端的请求落在同一台服务器上
    # server 192.168.1.23; 
    server 192.168.1.24;
    # server 192.168.1.25;
    keepalive 32;
    }