Configure NextCloud & Nginx Reverse Port Forward - Login Authentication Error - nginx

Question

I have set up an nginx reverse proxy server on my web server, which is receiving SSL traffic, and reverse proxying it to port 8080 on my web server, which is an exposed port running the nextcloud docker image. I am able to log in from a desktop web browser, but I am not able to log in from my iPhone. When I log in from the app, I receive error message "Access Forbidden, Invalid Request." This Github issue identifies the issue as auth headers being removed from the request, though the solution it gives is for Apache, not for Nginx. I'm really not familiar with authorization headers. How would I modify my Nginx server directive to take care of the issue?
Current setup
server {
listen 443 ssl;
listen [::]:443 ssl;
server_name cloud.foo.com;
ssl_certificate /etc/letsencrypt/live/cloud.foo.com/fullchain.pem; # managed by Certbot
ssl_certificate_key /etc/letsencrypt/live/cloud.foo.com/privkey.pem; # managed by Certbot
include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
location / {
proxy_pass http://127.0.0.1:8080/;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;
}
}

Answer 1

You may need to add a setting to explicitly pass the Authorization header in the response from the proxied server.
For example:
location / {
proxy_pass http://127.0.0.1:8080/;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;
proxy_pass_header Authorization;
}
Based on the reverse proxy settings I've seen for another authenticated service, it's probable that by default, Nginx does not pass the Authorization header from the response of a proxied server to a client. Although this is not listed in the documentation, it is probably necessary to avoid interference with the authentication modules.