What is the url behind proxy_pass of nginx reverse proxy?

Question

What is the url behind proxy_pass of nginx reverse proxy? The 127.0.0.1 written in the example below represents the local machine? Represent yourself? What is the function?

    location / {
        proxy_http_version       1.1;

        add_header               Strict-Transport-Security "max-age=31536000; includeSubDomains; preload";
        add_header               X-Frame-Options deny;
        add_header               X-Content-Type-Options nosniff;
        add_header               Content-Security-Policy "default-src 'none'; script-src 'unsafe-inline' 'unsafe-eval' blob: https:; img-src data: https: http://ip.qgy18.com; style-src 'unsafe-inline' https:; child-src https:; connect-src 'self' https://translate.googleapis.com; frame-src https://disqus.com https://www.slideshare.net";
        add_header               Public-Key-Pins 'pin-sha256="YLh1dUR9y6Kja30RrAn7JKnbQG/uEtLMkBgFF2Fuihg="; pin-sha256="aef6IF2UF6jNEwA2pNmP7kpgT6NFSdt7Tqf5HzaIGWI="; max-age=2592000; includeSubDomains';
        add_header               Cache-Control no-cache;

        proxy_ignore_headers     Set-Cookie;

        proxy_hide_header        Vary;
        proxy_hide_header        X-Powered-By;

        proxy_set_header         X-Via            QingDao.Aliyun;
        proxy_set_header         Connection       "";
        proxy_set_header         Host             imququ.com;
        proxy_set_header         X-Real_IP        $remote_addr;
        proxy_set_header         X-Forwarded-For  $proxy_add_x_forwarded_for;

        proxy_pass               http://127.0.0.1:9095;
    }

Answer 1

There is a port behind the IP
Forward the request to port 80 to port 9095, because nginx itself cannot handle the request of java/php/python (just for example), it needs to be handed over to tomcat, php-fpm or wsgi, etc. To handle it, so a reverse proxy backend service is needed. Personal understanding

Answer 2

I think you can also write other IPs, not necessarily this machine, as long as this machine can access it

Answer 3

Other IPs can be used. The purpose is to realize the proxy. Simply understood as CDN, it can also be used, but the functions are complete and available

Answer 4

127.0.0.1 refers to this machine, why do you need to proxy yourself? For example, the server is running node.js server, but node.js is not a dedicated web server, so Nginx is required to reverse proxy, which makes it much more convenient to control external access, and Nginx caching can improve performance.