1、安装 openresty 依赖模块：

[root@Centos opt]# yum -y install pcre-devel openssl openssl-devel postgresql-devel

2、编译安装 openresty：

[root@Centos opt]# tar -zxvf openresty-1.15.8.2.tar.gz
…（略去内容）…
[root@Centos opt]# cd openresty-1.15.8.2/
[root@Centos openresty-1.15.8.2]# ll
总用量
drwxrwxr-x. hacker 11月 : build
drwxrwxr-x. hacker 8月 : bundle
-rwxrwxr-x. hacker 8月 : configure
-rw-rw-r--. hacker 8月 : COPYRIGHT
-rw-r--r--. root root 11月 : Makefile
drwxrwxr-x. hacker 8月 : patches
-rw-rw-r--. hacker 8月 : README.markdown
-rw-rw-r--. hacker 8月 : README-windows.txt
drwxrwxr-x. hacker 8月 : util
[root@Centos openresty-1.15.8.2]# ./configure --prefix=/usr/local/openresty --with-luajit --without-http_redis2_module --with-http_iconv_module --with-http_postgres_module
…（略去内容）…
[root@Centos openresty-1.15.8.2]# gmake && gmake install
…（略去内容）…

3、编辑 nginx.conf 文件，编辑后内容为：

http {
include mime.types;
default_type application/octet-stream;

sendfile        on;  
keepalive\_timeout  ;

lua\_shared\_dict ups\_zone 1m; # 定义upstream共享内存空间

upstream web-cluster {  
    server 127.0.0.1:;  
    server 127.0.0.1:;  
}

upstream web- {  
    server 127.0.0.1:;  
}

upstream web- {  
    server 127.0.0.1:;  
}

server {  
    listen       ;  
    server\_name  localhost;  
    #charset koi8-r;

    #access\_log  logs/host.access.log  main;

    location /forward {  
        default\_type text/html;  
        content\_by\_lua\_block {  
           local host = ngx.req.get\_uri\_args()\["host"\]  
           local key = "switchKey"  
           ngx.shared.ups\_zone:set(key, host)  
           local forward\_ip = ngx.shared.ups\_zone:get(key)  
           ngx.say("Successfully, forwarded host is: ", forward\_ip)  
        }  
    }

    location ~ /web/(.\*) {  
       set\_by\_lua\_block $my\_ups {  
           local key = ngx.shared.ups\_zone:get("switchKey")  
           if key == nil or key == "default" then  
              return "web-cluster"  
           else  
              local port = string.sub(key, -)  
              if port == "" then  
                 return "web-8087"  
              elseif port == "" then  
                 return "web-8088"  
              end  
           end

       }

       proxy\_pass http://$my\_ups/$1;

    }

}  

}

4、测试是否生效：

（1）默认负载均衡模式：

[root@Centos conf]# curl http://127.0.0.1/forward?host=default
Successfully, forwarded host is: default
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]#

（2）将所有请求转移到 8087 server：

[root@Centos conf]# curl http://127.0.0.1/forward?host=127.0.0.1:8087
Successfully, forwarded host is: 127.0.0.1:
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]#

（3）将所有请求转移到 8088 server：

[root@Centos conf]# curl http://127.0.0.1/forward?host=127.0.0.1:8088
Successfully, forwarded host is: 127.0.0.1:
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]# curl http://127.0.0.1/web/lua
server
[root@Centos conf]#

参考书籍：《OpenResty最佳实践》PDF版，《OpenResty完全开发指南》