nginx/1.26.1 as a reverse proxy strips the Content-Length field from response, no matter what I do

[Tobias Damisch]

Hi everyone, first-time poster here.

I am trying to run nextcloud AIO behind a nginx/1.26.1 reverse proxy.
When I download a file from the nextcloud, in the answer there is no
Content-Length field coming out of nginx, while it was there when
nextcloud AIO sent it (I have sniffed the traffic with tcpdump on the
server before it enters nginx). This causes the file download in my
browser to not show download progress.

I have googled and experimented with all related settings that I could
find online for several days now, to no avail.

If anyone could tell me how to get nginx to hand over the
Content-Length, I'd be extremely grateful!


My current /etc/nginx/conf.d/default.conf:
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server {
     listen       80;
     server_name  localhost;

     location /.well-known/acme-challenge/ {
         root /var/www/certbot;
     }

     location / {
         root   /usr/share/nginx/html;
         index  index.html index.htm;
     }
}

server {
     listen      443 ssl;

     server_name url.net;
     location / {
         proxy_pass http://127.0.0.1:11000;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header Host $host;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         # if we comment this out, uploads fail
         client_max_body_size 0;

         # I have tried the following options, but none work.

         proxy_buffering off;

         proxy_pass_request_headers on;
         proxy_pass_header Content-Length;

         proxy_set_header X-Forwarded-Proto $scheme;

         gzip off;
         proxy_request_buffering off;
         chunked_transfer_encoding off;

         # /options I have tried

         # Websocket
         proxy_http_version 1.1;
         proxy_set_header Upgrade $http_upgrade;
         proxy_set_header Connection $connection_upgrade;
     }
     ssl_certificate /etc/letsencrypt/live/url.net/fullchain.pem; #
managed by Certbot
  # managed by certbot on host machine
     ssl_certificate_key /etc/letsencrypt/live/url.net/privkey.pem;
  # managed by Certbot
}
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My /etc/nginx/nginx.conf:
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user  nginx;
worker_processes  auto;

error_log  /var/log/nginx/error.log notice;
pid        /var/run/nginx.pid;


events {
     worker_connections  1024;
}


http {
     include       /etc/nginx/mime.types;
     default_type  application/octet-stream;

     log_format  main  '$remote_addr - $remote_user [$time_local]
"$request" '
                       '$status $body_bytes_sent "$http_referer" '
                       '"$http_user_agent" "$http_x_forwarded_for"';

     access_log  /var/log/nginx/access.log  main;

     sendfile        on;
     #tcp_nopush     on;

     keepalive_timeout  65;

     #gzip  on;


     ##
     # Connection header for WebSocket reverse proxy
     ##
     map $http_upgrade $connection_upgrade {
         default upgrade;
         ''      close;
     }

     include /etc/nginx/conf.d/*.conf;
}
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