OK, so for anyone who might stumble across this in the future; I solved it. Kinda.
Basically, what's happening is that lemmy is using the site URI for the human-readable content and /api for api stuff (including login, loading and a bunch of other stuff).
I tried setting up two sites in the tunnel; one to lemmy.mydomain and one to lemmy.mydomain/api but that didn't seem to work. Presumably due to websocket calls not being re-routed.
What I opted to do was to setup lemmy.mydomain to my Nginx Reverse Proxy (I manage it using Nginx Proxy Manager). From there I added a proxy host pointing to my lemmy ui docker container and created a custom location for /api, pointing to the backend at port 8536.
The result is working great and all functions (that I've tested so far) is working without a hitch! Certificates are automatically managed by Cloudflare and I also get the adde dbenefit that Cloudflare offers on DNS and filtering while allowing access to my lemmy instance.
Has anyone successfully setup lemmy in docker and using Cloudflare Tunnel?
Edit: Solved! See solution in comments
I’ve setup a self hosted lemmy docker and it works when accessing directly on the same subnet.
I don’t have ports opened in my firewall and my ISP don’t offer static IP so I rely on Clouflare tunnel as an alternative.
I’m able to load the front page, but can’t sign in. I don’t cache JavaScript through Cliudflare so I believe it’s relating to Websockets, but curious if anyone else has been able to get this working?