Ubuntu Nginx Reverse-Proxy LXC uses disk quota of Backend Server?

[ivenae]

I have a strange phenomen.
I use an Ubuntu 22.04 Nginx LXC as a Reverse-Proxy for another Ubuntu LXC with "filebrowser" installed.
To central manage my certs with certbot, the insecure http backend connection with filebrowser is encapsulated to https to the outer world on this nginx machine.

The disk quota of the nginx bootdisk is only 1 GB disk space, but if i transfer large files, i see the disk quota goes up and the connection is slowed down when the quota of 1 GB is reached (maximum usage: 1,6 GB with about 0,6 GB usage of the ubuntu machine)
I put the quota to 5 GB an the problem is gone. nginx only uses 1 GB as disk cache.

I tried to disable the cache in nginx, but nothing chanced.
I also cannot find the place, where the quota is used. It is not in the cache dir of nginx, nor can i localize the quota files with du -sh /*

Could the reverse proxy somehow use the quota of the backend filebrowser ubuntu via file pipes or another magic process i did not understand?how can i find the location of the quota used by nginx and how can i disable it completly? cache should only be stored into RAM and not waste my SSD capacity or wearout.

 

[ivenae]

Seems to be proxy request buffer:
https://docs.nginx.com/nginx-management-suite/acm/how-to/policies/configure-proxy-buffers/

changed as follows: (add from proxy_buffering to proxy_max_temp_file_size)

server {
        server_name external.domain.de
        location / {
                proxy_pass      https://192.168.178.250;
                proxy_set_header Host $host;
                proxy_set_header X-Real-IP $remote_addr;
                proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
                proxy_ssl_verify              off;
                proxy_buffering                 off;
                proxy_request_buffering         off;
                client_body_buffer_size         0;
                client_max_body_size            0;
                proxy_max_temp_file_size        0;
        }
        client_max_body_size 0;

solved.