Add support for checkpoint conversion for different container runtimes/engines about checkpointctl HOT 3 OPEN

checkpointctl migrate/convert --from {podman,cri-o,kubernetes} --to {podman,cri-o,kubernetes} /tmp/ubuntu_looper.tar.gz

We had a short discussion about the name of the command (#125 (comment)) and it seems like checkpointctl convert would be more appropriate for this feature.

I'm not sure if I understand the purpose of --from / --to kubernetes, i.e., CRI-O and containerd are used by Kubernetes. They implement the checkpointing functionality.

from checkpointctl.

There should be no difference between runc/crun (I hope). The crun support was added based on what runc does. If crun does something differently we should try to fix crun.

Overall I would hope that it is possible to restore a checkpoint archive with any container archive. The differences are mainly in metadata and the goal should be to use the same metadata everywhere and if not possible handle the differences in the engines.

from checkpointctl.

Adding a note here that Podman currently does not support restoring with a different runtime than the one used to create the checkpoint.

$ sudo podman container restore --runtime=runc  -i /tmp/cr1.tar
Error: checkpoint archive /tmp/cr1.tar was created with runtime 'crun' and cannot be restored with runtime 'runc'

from checkpointctl.