podman: add runit service

[lemmi]

Upstream Systemd service doesn't do anything special. --time=0 unix:///var/run/docker.sock is required, since we don't have socket activation.

[lemmi]

Oh, I thought the main point of the service is to replace docker. I never thought about starting the service for anything else. What would one use it for, if not for a docker replacement?

[CameronNemo]

Hmm. Perhaps defaulting to the docker socket makes sense then. But having it configurable is good in my opinion. E.g. for those that want remote access. Also the log level could be configurable too.

So my recommendation is OPTS="--log-level info unix:///var/run/docker.sock" in a conf file then exec podman system service --time=0 $OPTS in the service.

[lemmi]

I can live with that. I'd still love to hear from @leahneukirchen, what they think about it.

[leahneukirchen]

Imo the service should be used with sudo podman --remote, which defaults to /run/podman/podman.sock.

[the-maldridge]

Hmm, perhaps we should have two services, because my intent was to use this to replace docker completely.

[lemmi]

@the-maldridge yeah, I was thinking the same.
I also had another look around. Seems like upstream suggests this solution. They start podman with the default location, but provide a systemd config that creates a symlink from the docker default socket path to the podman socket path.
Maybe we could mimick that by providing a podman service with default options and optional config and a podman-docker service, that adds the symlink.

[leahneukirchen]

Note that podman starts the socket with hard-coded 0700 permissions, so it's only usable by root by default anyway.

If you want to "replace docker completely", I don't see the problem here as just using podman instead of docker (or even aliasing it) will work. From personal experience, I'd recommend not using the docker client to speak to a podman server if you can avoid it.

[lemmi]

As promised, I added the podman and podman-docker services. Tell me if that works for you this way.

[the-maldridge]

@leahneukirchen @CameronNemo I am happy with the changes in this PR, do you have any concerns before I merge this?

[CameronNemo]

LGTM

[Duncaen]

I don't think the fake service for the symlink is necessary or required, why not just add that to the normal service?

[lemmi]

@Duncaen that was my first suggestion, but we decided against it.