Stop supporting cri-dockerd directly

[jandubois]

We added (and configured) cri-dockerd because k8s dropped docker-shim in the 1.24 release.

However, k3s has added cri-dockerd in 1.24.4, so only 3 releases 1.24.1, 1.24.2, and 1.24.3 don't support the --docker option (there was non 1.24.0+k3s release afaik).

We should switch back to using the --docker option, now that it is supported again going forward, and simply tell the user that they have to use the containerd engine with the 3 releases that don't support docker. That slightly reduces our download size and complexity, but more importantly we will run in the same configuration as if you used k3s directly.

• Remove cri-dockerd (and cni-plugins?) from alpine-lima and wsl-distro.
• Use --docker option when configured with the moby engine.
• Prevent the user from selecting moby when k3s is 1.24.{1,2,3}.
• When upgrading from 1.24.{1,2,3} and moby engine, display a dialog¹
• Create diagnostic to inform about the "hidden" images, in case they didn't read the dialog. 😄

Footnotes

1. The warning should explain that moby is not supported with their current Kubernetes version, and that we had to switch them to containerd. If they want to regain access to their existing images, they should switch to a version of k3s that supports --docker. ↩

[jandubois]

Another argument to rely on cri-dockerd bundled with k3s is that in the future we may need different cri-dockerd versions depending on the k8s version: Mirantis/cri-dockerd#125

[gaktive]

#1766 was the PR that introduced cri-dockerd, so we need logic to detect the version for the 3 in question with this; otherwise this is almost a revert of that.

[jandubois]

It looks like the version of cri-dockerd bundled with the current release of k3s is not compatible with docker 25.* (k3s-io/k3s#9279), so we may need to continue bundling it.

Ideally we should bundle cri-dockerd from https://github.com/k3s-io/cri-dockerd because there may be additional patches for k3s, but there are no binary releases in that repo (it is built as part of k3s itself). Needs further investigation.