Docker support deprecated


Is Rancher (K8s) going to support containerd as an alternative supported container runtime instead of Docker?

Docker support in the kubelet is now deprecated and will be removed in a future release. The kubelet uses a module called “dockershim” which implements CRI support for Docker and it has seen maintenance issues in the Kubernetes community. We encourage you to evaluate moving to a container runtime that is a full-fledged implementation of CRI (v1alpha1 or v1 compliant) as they become available. (#94624, @dims) [SIG Node]

We already do; Rancher doesn’t care what CRI is used below a cluster when managing resources inside it. RKE2 and k3s both already use containerd.

For assembling new clusters through node drivers, one or both will become integrated with the provisioning process that currently uses RKE[1] in a future release.

Deprecated also means “still works fine until at minimum v1.23 in mid 2021”.

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What I wold like of see is the ability to specify to create a k3s cluster from the ui (which as you said already uses containerd). Of course you can in create one (k3s cluster I mean) with the k3d cli utility first and then import it. But we are training people to use rancher and it’s more efficient to do everything in one place. Personally I prefer cli. However rancher ui is a powerful tool with a few extra features and like I said if we are going to use it at all it is just better to have most things in one place. And platform changes can painful, even if it it is only the underlying runtime, so we are keen on wanting to use fully compliant infrastructure. I’m actually surprised this hasn’t already been implemented, given the fact that rancher seems to have though of almost everything else!

This sounds great. Is the plan then to autodetect containerd (if it’s running) and use it instead of docker?