lua 動態修改upstream

基於 OpenResty  balancer_by_lua 配置指令, 利用 ngx.crc32_long 根據源地址與目的端口生成hash， 實現一個簡單的 ip_hash upstream. 僅供參考 

upstream backend{
    server 0.0.0.0;
    balancer_by_lua_block {
        local balancer = require "ngx.balancer"
        local host = {"192.168.1.111", "192.168.1.112"}
        local backend = ""
        local port = ngx.var.server_port
        local remote_ip = ngx.var.remote_addr
        local key = remote_ip..port
        local hash = ngx.crc32_long(key);
        hash = (hash % 2) + 1
        backend = host[hash]
        ngx.log(ngx.DEBUG, "ip_hash=", ngx.var.remote_addr, " hash=", hash, " up=", backend, ":", port)
        local ok, err = balancer.set_current_peer(backend, port)
        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, ":", port)
    }
}

server {
    listen 80;
    listen 8080;
    listen 7777;
    server_name *.x.com
    location / {
        proxy_pass http://backend;
    }
}

例子2：

 

http {
    upstream backend {
        server 0.0.0.1;   # just an invalid address as a place holder

        balancer_by_lua_block {
            local balancer = require "ngx.balancer"

            -- well, usually we calculate the peer's host and port
            -- according to some balancing policies instead of using
            -- hard-coded values like below
            local host = "127.0.0.2"
            local port = 8080

            local ok, err = balancer.set_current_peer(host, port)
            if not ok then
                ngx.log(ngx.ERR, "failed to set the current peer: ", err)
                return ngx.exit(500)
            end
        }

        keepalive 10;  # connection pool
    }

    server {
        # this is the real entry point
        listen 80;

        location / {
            # make use of the upstream named "backend" defined above:
            proxy_pass http://backend/fake;
        }
    }

    server {
        # this server is just for mocking up a backend peer here...
        listen 127.0.0.2:8080;

        location = /fake {
            echo "this is the fake backend peer...";
        }
    }
}

參考：https://github.com/openresty/lua-resty-core/blob/master/lib/ngx/balancer.md

          https://github.com/openresty/lua-resty-balancer

          https://github.com/openresty

          https://www.nginx.com/resources/wiki/modules/lua/

          https://github.com/openresty/lua-nginx-module