document pocketbase SSE authentication solution

[McNull]

I had some issues setting up upsnap behind nginx proxy manager (reverse proxy). Authentication fails silently in the ui (network tab shows details). This has to do with the use of Server-Sent Events (SSE) in PocketBase, which is used for auth-refresh and some installer flows. The reverse proxy needs to forward the correct headers and disable buffering to allow SSE to work properly.

To fix this simply add this as custom config to the proxy host entry:

proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
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_set_header X-Forwarded-Proto $scheme;
proxy_read_timeout 3600s;
proxy_send_timeout 3600s;
proxy_buffering off;
proxy_cache off;
chunked_transfer_encoding off;

This will allow the SSE connection to pass through the reverse proxy without being broken, and authentication will work as expected.

Since NPM is quite popular, maybe this should be added to the upsnap documentation to help others avoid the same issue.