Migrating to Podman

I run everything in rootless containers using systemd service files generated with podman generate systemd.

Podman Compose is a "community effort", and Red Hat seems to be less focused on its development (here is their post about it).

There are ways to get it working but I find it easier to go with podman containers and pods through systemd because the majority of documentation (both official and unofficial) leans in that direction.

I don't know how much you already know, so here is just a summary of things that worked for me for anyone reading.

Podman uses the concept of "Pods" to link together associated containers and manage name spaces, networking, etc. The high level summary for running podman pods through systemd:

• Create an empty pod podman pod create --name=<mypod>.
• Start containers using podman run --pod=<mypod> ... and reconfigure until containers are working within the same pod as desired.
• Use podman generate systemd to create a set of systemd unit files. Be sure to read through the options in that man page. -- this is more reliable than creating systemd unit files by hand because it creates unit files optimized for the podman workflow.
• place the generated systemd unit files in the right place (user vs. system) and then it can be started, enabled, and disabled as with other systemd unit files.

Note: for standalone containers that are not linked or reliant on other containers, you can should skip creating the empty pod and can skip the --pod=<mypod> when starting containers. This should result in a single service file generated and that container will operate independently.

This post goes over pods as systemd services.

This doc goes over containers as systemd services.

The Red Hat Enterprise Linux docs have a good amount of info, as well as their "sysadmin" series of posts.

Here are some harder to find things I've had to hunt down that might help with troubleshooting:

• Important: be sure to enable loginctl enable-linger <username> or else rootless pods/containers will stop when you log out of that session.
• If you want it to run a container or pod at system startup you will need to specify the right parameters in the [Install] section of the systemd file, see this doc page. Podman generate systemd should take care of this.
• If you are using SELinux there is a package called container-selinux that has some useful booleans that can help with specific policies (container-use-devices is a good one if your container needs access to a GPU or similar). Link to repo

I gave podman a try a few months ago and went with systemd unit files instead of compose files, since it felt like the most native approach.

Podman compose kinda sucks. Better use the now included Quadlet container files for Systemd integration.

Also very interested in this.

Interesting, and why do you want to switch?

Podman-compose is a python script that simply converts a compose file to 'podman run'. It worked fine enough for me, but the caveat being it doesn't have full feature parity and the errors aren't as good. The only thing I couldnt get working was connecting my GPU to jellyfin.

Turning conainers into systemd units is easy: 'podman generate systems --new --name $container_name › $HOME/.config/systems/user/$container_name.service' 'systemctl --user enable --now $container_name'

https://docs.podman.io/en/latest/markdown/podman-generate-systemd.1.html

In my case I just installed podman compose :)

Podman's strong suite is integration with other toolings, such as systemd and ansible.

With ansible I could define a podman pod and containers in a playbook yml file. And Ansible can do much more, like provisioning the configuration files or setting an auto update service for podman

The gotcha with podman is it's networking is different from docker. So I would at least plan it out before migrating.

Check out Podlet to convert your existing docker run commands or docker-compose.yaml files to quadlet files https://github.com/k9withabone/podlet

I’ve no experience with Podman but genuinely interested why would you use this instead of Docker/Kubernetes?