使用balancer_by_lua_block做应用层负载均衡

首先感谢章义春大神的openresty，解决了web开发的一些痛点并简化了web开发的复杂度。

需求：

根据url的一个参数，做负载均衡，使得某一个用户总是被分配到固定的业务服务器上处理，方便后续的业务处理，做缓存或单元化架构部署

假设这个参数为dvid，一共有两个业务服务器, 8088端口和8089端口，分别返回hello和world

server{
listen 8088;
        location /hello {
            content_by_lua ’
            ngx.say(“hello”)
            ’;
    }
}
server{
listen 8089;
        location /hello {
            content_by_lua ’
            ngx.say(“world”)
            ’;
    }
}

    server{
    listen 8088;
            location /hello {
                content_by_lua '
                ngx.say("hello")
                ';
        }  
    }
    server{
    listen 8089;
            location /hello {
                content_by_lua '
                ngx.say("world")
                ';
        }  
    }  

upstream  balancer_by_lua_block的配置：

    upstream backend{
        server 0.0.0.0;
        balancer_by_lua_block {
            local balancer = require “ngx.balancer”
            local port = {8088, 8089}
            local backend = “”
            local dvid = ngx.req.get_uri_args()[“dvid”] or 0
            ngx.log(ngx.ERR, ”dvid=”, dvid)
            local hash = (dvid % 2) + 1
            ngx.log(ngx.ERR, ”hash=”, hash)
            backend = port[hash]
            ngx.log(ngx.ERR, ”backend=”, backend)
            ngx.log(ngx.ERR, ”dvid=“, dvid, ” hash=“, hash, ” up=”, backend)
            local ok, err = balancer.set_current_peer(“127.0.0.1”, backend)
            if not ok then
                ngx.log(ngx.ERR, “failed to set the current peer: ”, err)
                return ngx.exit(500)
            end
            ngx.log(ngx.DEBUG, “current peer ”, backend)
        }
    }

    upstream backend{  
        server 0.0.0.0;  
        balancer_by_lua_block {   
            local balancer = require "ngx.balancer"    
            local port = {8088, 8089}    
            local backend = ""  
            local dvid = ngx.req.get_uri_args()["dvid"] or 0
            ngx.log(ngx.ERR, "dvid=", dvid)
            local hash = (dvid % 2) + 1   
            ngx.log(ngx.ERR, "hash=", hash)
            backend = port[hash]  
            ngx.log(ngx.ERR, "backend=", backend)
            ngx.log(ngx.ERR, "dvid=", dvid, " hash=", hash, " up=", backend)  
            local ok, err = balancer.set_current_peer("127.0.0.1", backend)  
            if not ok then  
                ngx.log(ngx.ERR, "failed to set the current peer: ", err)  
                return ngx.exit(500)  
            end  
            ngx.log(ngx.DEBUG, "current peer ", backend)  
        }   
    } 

接收业务请求的server：

server {
    listen       80;
    server_name  localhost;

    #charset koi8-r;

    #access_log  logs/host.access.log  main;

    location / {
        root   html;
        index  index.html index.htm;
    }
    location /hello {
        proxy_pass http://backend;
    }
    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   html;
    }

}

    server {
        listen       80;
        server_name  localhost;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            root   html;
            index  index.html index.htm;
        }
        location /hello {
            proxy_pass http://backend;
        }   
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

    }

测试：

http://localhost/hello?dvid=1   返回world

http://localhost/hello?dvid=2   返回hello

测试结果OK

openresty安装：

https://openresty.org/en/download.html

wget https://openresty.org/download/openresty-1.11.2.2.tar.gz

tar zxf openresty-1.11.2.2.tar.gz

cd openresty-1.11.2.2/

./configure –with-luajit&& make && make install

参考：

http://weibo.com/1834459124/DaEmgBhlD?from=singleweibo&mod=recommand_weibo&type=comment#_rnd1479734607640

http://blog.csdn.net/force_eagle/article/details/52224660

http://www.wtoutiao.com/p/177SJDc.html