NGINX 结合 lua 动态修改upstream

from http://blog.csdn.net/force_eagle/article/details/51966333

 

具体思路是： 

1 > 利用lua中 "lua_shared_dict" 指令开辟一个共享内存空间;

2> 通过API动态根据key值&参数修改 upstream  (这里使用 host 作为key);

3> 利用 proxy_pass 可使用变量特性及lua指令 "set_by_lua" 动态修改当前 upstream 变量即可；

 

以下是利用 qq.com 作为示例:

 

http {
    lua_shared_dict _ups_zone 64m; # 定义upstream共享内存空间
    ...
    upstream qq_backend{
        server 14.17.42.40;
        server 14.17.32.211;
        server 59.37.96.63;
    }

    server {
        listen       80;
        server_name  www.qq.com *.qq.com;
        access_log  off;

        # 更新 upstream API 接口
        location = /ups_update {
            content_by_lua '
                local ups = ngx.req.get_uri_args()["ups"]
                if ups == nil then
                    ngx.say("usage: /ups_update?ups=x.x.x.x")
                    return
                end
                local host = ngx.var.http_host
                local ups_from = ngx.shared._ups_zone:get(host);
                ngx.log(ngx.WARN, host, " update upstream from ", ups_from, " to ", ups)
                ngx.shared._ups_zone:set(host, ups);
                ngx.say(host, " update upstream from ", ups_from, " to ", ups)
            ';
        }
        location / {
            # 动态设置当前 upstream, 未设置则使用默认 upstream
            set_by_lua $cur_ups '
                local ups = ngx.shared._ups_zone:get(ngx.var.http_host)
                if ups ~= nil then
                    ngx.log(ngx.ERR, "get [", ups, "] from ngx.shared._ups_zone")
                    return ups
                end
                --ngx.log(ngx.INFO, "use default upstream");
                return "qq_backend";
            '
            proxy_next_upstream off;
            proxy_set_header    Host $host;
            proxy_http_version  1.1;
            proxy_set_header    Connection  "";
            proxy_pass $scheme://$cur_ups;
        }
    }
}

 

cur -x 127.0.0.1:80 www.qq.com  # 使用默认upstream
# 修改为140.206.160.207 & 61.135.157.156
curl -x 127.0.0.1:80 www.qq.com/ups_update?ups=140.206.160.207
curl -x 127.0.0.1:80 www.qq.com/ups_update?ups=61.135.157.156

 

这里只是一个简单的思路，并未考虑到 upstream 持久化，如需要可参考以下这篇文章, 使用 Redis 来实现:

Dynamic nginx upstreams with Lua and Redis