How to make a redirect in nginx if the user sends a file?

Question

Nginx

There are two servers: application server and file server.
There are many methods that save files on the server.
You need to do this: when the user submits the form (it is located on the application server) to save the file, the entire request must be proxied to the file server while maintaining the same url
How to determine that the user sent a POST request to save the file?

Answer 1

It can be determined using an additional condition in the location section.
For example, like this:

location /postfiles {
  # проксируем post-запросы
  if ($request_method ~ ^(POST)$ ) {
    proxy_pass  http://fileserver.com/postfiles/$is_args$args;
    break; 
  } 
  
  #тут обработка остальных, не-post запросов
  try_files $uri $uri/ /index.php?$query_string;
}