nginx. How to make a site mirror through Proxy pass?

Question

Nginx

Good afternoon.
I comprehend Nginx) Please tell me how to make a site mirror through Proxy pass?
That is, when you go to the SITE1.COM site, SITE2.COM is loaded without changing the address. Ie not a redirect as a matter of fact.
Is it possible at all?
Tried like this:

server {
    listen 9999;
    server_name site1.com;
    access_log /var/log/nginx/test/access.log;
    error_log /var/log/nginx/test/error.log;

location / {
    proxy_pass http://site2.com
    proxy_redirect off;
    proxy_set_header Host $host;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Real-IP $remote_addr;
    }
}

But there is a redirect

Answer 1

location / {
                resolver 8.8.8.8;

                proxy_cache my_cache;

                proxy_pass https://example.com;
                proxy_redirect off;

                proxy_intercept_errors on;

                proxy_set_header X-Forwarded-Host $host;
                proxy_set_header X-Forwarded-Server $host;
                proxy_set_header Host example.com;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-Proto $scheme;
        }

taken from a currently working proxy
, you can access it both at example.com
and at the address (domain name) on which this same nginx is installed.
simultaneously.