Jellyfin and Jellyscrub in Docker with unprivileged jellyfin user (fixes player not showing thumbnails)
Jellyscrub needs to be able to write to Jellyfin's index.html. If you're running Jellyfin as an unprivileged user it won't be able to, since the official container jellyfin files are owned by root.
This is a docker-compose example of how to work around this problem. The docker-compose service definition for jellyfin also passes through an intel igpu. Leaving here as this might be useful to someone.
Once adding the below, make sure you build the container, delete the old one and bring up a new one with
docker-compose down jellyfin && docker-compose up -d. Any changes to the dockerfile or build params also mandate this.