Skill set: When Nginx is acting as an agent, see which server the request is forwarded to

When using Nginx proxy for multiple servers, how do you see which server the request was forwarded to?

Upstream Demo {      server 127.0.0.1:8781;
     Server 127.0.0.1:8087;
}

Add the following red configuration:

    server {        listen       ;        server_name  demo.testcas.com;        #charset Koi8-r;        #access_log  logs/host.access.log  main;        Location/{            #root   html;            #index  index.html index.htm;　　　　　　 add_header Backendip $upstream _addr; Add_header backendcode $upstream _status;   Proxy_pass Http://demo;        }    }

Restart Nginx, re-access, in the browser F12 view request headers information, you can see the current server IP

Skill set: When Nginx is acting as an agent, see which server the request is forwarded to