How to preserve request url with nginx proxy_pass

Just proxy_set_header Host $host miss port for my case. Solved by:

    location / {
     proxy_pass http://BACKENDIP/;
     include /etc/nginx/proxy.conf;
    }

and then in the proxy.conf

    proxy_redirect off;
    proxy_set_header Host $host:$server_port;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

I think the proxy_set_header directive could help:

location / {
    proxy_pass http://my_app_upstream;
    proxy_set_header Host $host;
    # ...
}

Note to other people finding this: The heart of the solution to make nginx not manipulate the URL, is to remove the slash at the end of the Copy: proxy_pass directive. http://my_app_upstream vs http://my_app_upstream/ – Hugo Josefson

I found this above in the comments but I think it really should be an answer.

In case something modifies the location that you're trying to serve, e.g. try_files, this preserves the request for the back-end:

location / {
  proxy_pass http://127.0.0.1:8080$request_uri;
}