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Comment by szszrk | Hacker News Reader

How do you manage your containers in podman declaratively?

I tried to substitute docker-compose with Podman and Quadlets on a test server the other day, but was shocked how badly described the overall concept is. Most materials I found glimpsed through ability to run it as root/user and how different that is in configuration, and repeated the same 4-6 commands mantra.

Spent a few hours on it and just... failed to run a single container. systemctl never noticed my qualdet definitions, even if podman considered my .container file registered.

A bit.. frustrating, I expected smoother sailing.

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This has also been my experience, I'm used to using compose everywhere. I like the declarative file - tried podman and I found the documentation around the concept so scarce and all related to running things as non-root instead of telling me how my docker-compose becomes podman-compose. Still using docker everywhere because of that. Docker swarm mode has also worked wonders as an evolution to my compose files.

I know podman-compose, have some homelab services running on it for a few years, but honestly found multiple ones that failed. It's far from drop-in replacement.

Podman supports Compose files, so there's that. I've only glimpsed at Quadlets and I agree they seem very esoteric, especially if you're not very well versed in systemd service definitions.

The podman kube support? It provides similar functionality as docker-compose, using a yaml file which is a subset of the Kubernetes pod definition syntax.

Then you can just create a few line systemd unit definition, and it integrates as a normal systemd unit, with logs visible via journalctl etc.

This seems to be the way.

Short of weeding through the docs, I found the "Play with Kube using Podman" talk on DevConfs YouTube channel helpful.

I will be honest: that is even more confusing :)

> Note: The kube commands in podman focus on simplifying the process of moving containers from podman to a Kubernetes environment and from a Kubernetes environment back to podman.

I'll give it a try, but I'm starting to understand why there is so little use of podman among amateurs.

Personally, I am not interested in kubernetes, just podman for single-node use case. What the kube YAML does for this use case is provide a way to declare a multi-container application.

The podman documentation pages I have found most helpful for this use case are podman-kube-generate (generate kube YAML from an already running pod), podman-kube-play (run the kube manually) and podman-systemd.unit (run the kube as a service).

Edit: I should also mention that there are pod units (which don't require the use of kube YAML) but I skipped over them because they do not support podmans auto-update feature.

Yeah I think Quadlet just has bad docs. They document the whole API but iirc there is no: ok this is the hello world for running cowsay as a systemd unit

quadlets fully depend on systemd doing its work. So, assuming you are running rootless, if you change your quadlets, you will need

  systemctl --user daemon-reload

to let systemd ingest the changes. And, if you have configured to start your container on boot, then still you have to start the container by hand, as you typically won't reboot during development. If you have multiple containers, it might be easiest to have them in one pod, so you only need to start the pod.

I agree that the documentation needs a good tutorial to show the complete concept as a starting point. There are multiple ones though on the internet.

yeah, that's exactly what every tutorial says. And I know systemd more or less, daemon-reload is no stranger to me.

That was not sufficient. Both for global o user setup.

The biggest problem with the `systemctl daemon-reload (--user)` workflow to register quadlets with systemd is it hides any generation errors in journald instead of giving immediate feedback. It's a real pain in the ass, and I say this from a place of love.

Quadlets are just a systemd generator: all `daemon-reload` is doing is running `podman-system-generator` which looks at the Quadlet files and turns them into systemd unit files with a big honking `podman run --rm --blah container:tag` as the `ExecStart` property. There's nothing else to it, no daemons or what not

If you ever feel like bothering to give it another shot check journalctl to see if there's any generator errors. Or run the generator directly: on my OpenSUSE box it's at `/usr/lib/systemd/system-generators/podman-system-generator` , Run it with `--dry-run` to just output to stdout and `--user` to get user quadlets.

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