Container Runtime Support

Using the process as a primitive, cedana supports multiple container runtimes for checkpoint/restore. As we continue to abstract away the concept of what a container is (cgroups, overlay, namespaces, etc.) we'll continue to add support for more runtimes as well as increase support for currently supported ones.

Running containers

The container ecosystem can get confusing, especially when dealing with runtimes. Currently, cedana only supports containers using the runc low-level runtime. Below are the ones that we have tested with and support working with.

runtime/abstraction	level of support	well-tested?	notes
process	full	yes	simplest abstraction level, works with everything
runc	full	yes	simplest abstraction level, all other management layers need to be using runc
containerd (runc + rootfs)	full	yes	works well, works in kubernetes
kata containers	experimental	no	works with cedana, but need to increase test coverage
sysbox + crio (rootfs only)	full	yes	sysbox virtualization of proc and use of systemd makes process-level checkpoint/restore difficult
docker	mid	no	should just work
podman	mid	no	should just work, but untested in a little bit

Container rootfs

To support higher level container abstractions (like containerd, docker, etc) we perform a runc + rootfs checkpoint. Currently, you can directly perform a containerd checkpoint (which is a runc + containerd store rootfs checkpoint) and a separate crio rootfs checkpoint.