Honestly I’m not sure, or maybe I knew but forgot. Since working out my needs I wrote it to ansible and never looked back. Worth trying the more secure way for sure.

I do this on the minimal Debian release which is essentially coming from the same place, you’re left to get things configured with a root user or maybe a privileged user after install. There’s a few things to tweak for rootless podman and it will vary based on the distro. The gist for me and Debian is:

1. make an unprivileged account for running podman containers
2. enable linger so i can use systemd with this account and the running of the containers
3. allow lower ports for podman rootless in sysctl (for example, 80 if you’re running basic http services rootless), net.ipv4.ip_unprivileged_port_start=<start of lower range of ports rootless containers will use>
4. run containers with the appropriate --userns flags. This can vary a lot depending on the container. Some maintainers are nice and ensure the internal uid/gid is something expected like 1000, sometimes not and you have to fire it up and figure out the app account name, uid/gid. An example I’ll put here is a podman run snippet for running jenkins (official image from cloudbees) rootless:

podman run --name jenkins --user jenkins --userns=keep-id:uid=1000,gid=1000 ...

Again, that’s just Debian, never tried MicroOS, but if MicroOS isn’t doing anything special to accommodate rootless podman I imagine these steps are somewhat applicable. One issue I ran into was with an older version of Podman, whatever comes with Ubuntu 22: That version of podman requires you to set the namespace mappings; Debian 12’s version does not and the --userns=keep… flag just works.

I expose jellyfin to the internet, and some precautions I have taken that I don’t see mentioned in these answers are: 1) run jellyfin as a rootless container, and 2) use read-only storage where ever possible. If you have other tools managing things like subtitles and metadata files before jellyfin there’s no reason for jellyfin to have write access to the media it hosts. While this doesn’t directly address the documented security flaws with jellyfin, you may as well treat it like a diseased plague rat if you’re going to expose it. To me, that means worst case scenario is the thing is breached and the only thing for an attacker to do is exfiltrate things limited to jellyfin.