nginx - reverse proxy 反向代理
One of the frequent uses of nginx is setting it up as a proxy server, which means a server that receives requests, passes them to the proxied servers, retrieves responses from them, and sends them to the clients.
The proxy_pass directive is what makes this configuration a reverse proxy.
访问后端池的协议是http
后端池可以配置不同的port：
访问这个proxy的port 80端口后，流量会被送到后端服务器10.0.0.5的port 8080，或者送到10.0.0.6的port 80
