This is an enhancement proposal for the checkpoint / restore feature of
Podman that enables container migration across multiple systems with
standard image distribution infrastructure.
A new option `--create-image <image>` has been added to the
`podman container checkpoint` command. This option tells Podman to
create a container image. This is a standard image with a single layer,
tar archive, that that contains all checkpoint files. This is similar to
the current approach with checkpoint `--export`/`--import`.
This image can be pushed to a container registry and pulled on a
different system. It can also be exported locally with `podman image
save` and inspected with `podman inspect`. Inspecting the image would
display additional information about the host and the versions of
Podman, criu, crun/runc, kernel, etc.
`podman container restore` has also been extended to support image
name or ID as input.
Suggested-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Radostin Stoyanov <radostin@redhat.com>
CRIU's pre-copy migration support relies on the soft dirty page tracking
in the Linux kernel:
https://www.kernel.org/doc/Documentation/vm/soft-dirty.txt
This functionality is not implemented for all architectures and it can
also be turned off in the kernel.
CRIU can check if the combination of architecture/kernel/CRIU supports
the soft dirty page tracking and exports this feature checking
functionality in go-criu.
This commit adds an early check if the user selects pre-copy
checkpointing to error out if the system does not support it.
Signed-off-by: Adrian Reber <areber@redhat.com>
This adds support to checkpoint containers out of pods and restore
container into pods.
It is only possible to restore a container into a pod if it has been
checkpointed out of pod. It is also not possible to restore a non pod
container into a pod.
The main reason this does not work is the PID namespace. If a non pod
container is being restored in a pod with a shared PID namespace, at
least one process in the restored container uses PID 1 which is already
in use by the infrastructure container. If someone tries to restore
container from a pod with a shared PID namespace without a shared PID
namespace it will also fail because the resulting PID namespace will not
have a PID 1.
Signed-off-by: Adrian Reber <areber@redhat.com>
The upcoming commit to support checkpointing out of Pods requires CRIU
3.16. This changes the CRIU version check to support checking for
different versions.
Signed-off-by: Adrian Reber <areber@redhat.com>
Radostin Stoyanov
Valentin Rothberg
Adrian Reber