NGINX - Only proxy a specific URL

First, I have to admit that I’m a total n00b to NGINX. I have only done very basic work with it.

Now the situation. We have a reverse-proxy box in the DMZ that takes incoming connections/requests and “sends them along” to their destinations. Currently, one of these is allowing only connections from a specific subnet to be forwarded to a specific web server. This is to allow VPN user to reset a specific application password. Unfortunately, it forwards any requests for that web server’s URL along.

What I want: I need to lock this down. Instead of passing “https://webserver.com/whatever_they_type” to the server, I want to block everything except for a single, specific URL. ex: “https://webserver.com/this-url/only”
Everything else would get blocked.

Anyone have any thoughts on how to modify that location in NGINX to accomplish this?

---

Wondering if something like this would work?

    location = /good_page/reset_password.html {
            proxy_pass https://1.2.3.4:443;
            #### Set headers ####
            proxy_set_header Host webserver.com;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            #### Only allow OpenVPN networks ###
            allow 5.6.7.8/24;
            deny all;
    }


    location ^~ /good_page {
            deny all;
    }

    server {
       listen       80;
       server_name example.com www.example.com;
       access_log  /<access log file>  main;
       error_log  /<error log file>  error;

       # This is optional (any location)
       location / {
         # You can set a index.html with an error message
         root /path/folder;
       }
       # Specific prefix
       location /this-url/only/ {
          proxy_pass http://<your server IP>;
          <proxy configurations ...>;
       }
     }