#3322 is not a backward compatible change.

With an old containerd config, containerd can't even start:

containerd[1052]: containerd: invalid disabled plugin URI "restart" expect io.containerd.x.vx

This is somehow expected.

I thought about changing default to v1 https://github.com/Random-Liu/containerd/tree/default-to-v1, but on the other hand, I also think we need to move forward given the current release frequency, so let's at least document this in the release note.

At least, we should make sure we emphasize in the 1.3 release note that:

1. To continue using old containerd config, you need to add version = 1 in the config;
2. It is highly recommended to switch to version 2 config.

If we don't address this properly, I believe we'll get complained, and maybe a lot.

@containerd/containerd-maintainers