Websocket behind apache proxy

[AndiLeni]

Hello,

I am currently struggling a bit with my setup. I don't know where the issue is, so please bear with me if this is actually not a serverjs issue.
But it might help me to understand a few things better.

I have an Apache running on my server.
Via Apache proxy, my serverjs application serves a website at domain.de/abc. This is working fine so far.
However, I can not manage to establish a websocket connection.
The websocket should be available under the /abc path, so I tried to change the "path" options for websocket on both the client and the server.
The client now does send websocket requests to domain.de/abc/socket.io (the socket.io part seems to be a default value which I simply copied).
Unfortunately I only receive 404 or 503 errors, depending on what I tried in the proxy settings.

Are there any experiences for such a usecase?
Or any ideas I might try, settings to change?

Thanks and kind regards

[AndiLeni]

I was able to make it work.
The main issue was the order of my apache rules. The first matching rule gets applied, which caused my issues.

Here are my setting if anyone faces a similar issue:

ProxyPreserveHost On
RewriteEngine on
RewriteCond %{HTTP:Upgrade} websocket [NC]
RewriteCond %{HTTP:Connection} upgrade [NC]
RewriteCond %{REQUEST_URI} "/abc/socket.io"
RewriteRule ^/?(.*) "ws://localhost:3000/$1" [P,L]
        
ProxyPass "/abc/socket.io" ws://localhost:3000/$1
ProxyPassReverse "/abc/socket.io" ws://localhost:3000/$1
        
ProxyPass /abc http://localhost:3000/
ProxyPassReverse /abc http://localhost:3000/