Webmail via HTTPS (no reverse proxy)

[boku42]

Dear all,
I recently installed Roundcube docker image via portainer and trying to get it working with keycloak as authentication server via OAuth2.

I have spent quite a bit of time searching for options to expose roundcube via HTTPS but all I found was a co-deployment with reverse proxy for that. On the other hand, I see references to HTTPS in the config files but roundcube is not reachable on the HTTPS port (mapping). Since I already have a reverse proxy in my OPNsense, I would just like to add this capability to the standard installation.

Is it possible to use HTTPS and Letsencrypt certificates with the standard installation and if yes, how? I am wondering that no one else seems to have that question?

Thank you