Introduction for beginners?

[onlyjob]

I'm struggling to learn how to use Crun. Is there an intro with examples how to run a container, etc.?

Thanks.

[giuseppe]

The easiest way would probably be to use crun through a container engine such as Podman or CRI-O if you care about Kubernetes. FAIK, there is some work in progress for supporting crun also in containerd and in Moby/Docker.
I
If you'd like to use it directly, then you need a container image exploded on disk and already usable by crun since crun doesn't do any storage management.

Assuming you have a container image at rootfs, you can create a config file with crun spec:

$ ls -1
config.json
rootfs

At this point, you can tweak config.json with the configuration you wish.

I'd still suggest though to use it through a higher level tool as you won't have to worry about storage, or setup a network namespace beforehand

[onlyjob]

Interesting. Thank you. I think this information belongs to README to make it clear how Crun is expected to be used.

So how to use Crun with Podman, specifically? Is it documented anywhere?

[giuseppe]

in the Podman man page there is some info on how to configure and use a different OCI runtime:

https://github.com/containers/libpod/blob/master/docs/source/markdown/podman.1.md

[onlyjob]

Thank you.

It is quite easy to plug Crun to Podman by having the following in the /etc/containers/libpod.conf:

runtime = "crun"

[runtimes]
crun = [
    "/usr/bin/crun"
]

[giuseppe]

thanks for confirming it works for you. Can we close the issue?

[onlyjob]

I was hoping for some changes to README - just a few words about how to use Crun with Podman and a few words that Crun is a replacement to Runc rather than an alternative to rkt, Docker, etc...

[giuseppe]

I was hoping for some changes to README - just a few words about how to use Crun with Podman and a few words that Crun is a replacement to Runc rather than an alternative to rkt, Docker, etc...

yes that sounds like a good idea. Would you mind to open a PR with these improvements for the README file? I'll be happy to review it

[warmchang]

Hi, could you tell us what is the roadmap of crun project? It will replace the runc as the default runtime component in openshift?

[rhatdan]

@warmchang We have not made any decisions on that, at this point. Originally crun was for support for cgroupV2, but it also has some interesting features that runc does not, and @giuseppe is looking into adding additional features.

[rhatdan]

@onlyjob @giuseppe Should we update the readme and/or close this issue?

[warmchang]

@rhatdan I got it, and thank you for reply.

[onlyjob]

I would love to see some changes to README please, as requested here: #154 (comment)

Thanks.

[giuseppe]

I would love to see some changes to README please, as requested here: #154 (comment)

could you open a PR with the changes you'd like to add?

[rhatdan]

Since no PR was generated I am going to close.

[warmchang]

@warmchang We have not made any decisions on that, at this point. Originally crun was for support for cgroupV2, but it also has some interesting features that runc does not, and @giuseppe is looking into adding additional features.

https://docs.openshift.com/container-platform/4.12/nodes/containers/nodes-containers-using.html#nodes-containers-runtimes
It seems to be working in this direction. 😄