Hi,
I'm trying to deploy ghcr.io/pelican-dev/panel:latest on railway but I have a problem.
As stated in Pelican doc, I need to edit Caddyfile to allow reverse proxies to work with my panel. The problem I'm facing is that I don't wan't to create a custom image juste to edit 1 file so I would like to pass it as env and copy the content into the caddyfile before my container starts.

Something like that :
$CONFIG = My Caddyfile
Start command = "echo $CONFIG > /etc/caddy/Caddyfile && initial start command"

I tried to inspect the image to find the start command but it don't work if I use it manually for some reason :/

Is there a way to add my file into my container before it starts without editing the start command ? (I saw pre-deploy steps but as I understand it's not possible to edit files here because the filesystem is not persistent)