crictl vs ctr

TL;DR: ctr is containerd specific; crictl is kubeneretes related, for any container runtime.

• ctr is the CLI of containerd, not related to k8s.
  • ctr -v for containerd version.
• crictl is the CLI of CRI (Container Runtime Interface)
  • kubernetes uses crictl
  • for any CRI compliant runtime, e.g. docker, containerd, podman; kubernetes does not care which runtime it is.
  • crictl -v for kubernetes version.
  • config: /etc/crictl.yaml
• ctr image is namespaced: crictl image list = ctr -n=k8s.io image list

Which one to use?

If you are using Kubernetes, regardless of the actual runtime, use crictl;

If you are using containerd directly, use ctr.

Some functions may be provided by both CLIs:

crictl image = ctr -n=k8s.io images ls