Bug#943981: docker.io: Won't start under cgroupsv2

[Ryutaroh Matsumoto]

Dear Docker Maintainers and Systemd Maintainers for Debian,

Podman and podman-compose seem to work with no problem
on Debian Bullseye booted with systemd.unified_cgroup_hierarchy=1,
at least when podman is run by root.
Installation procedure is as below.
So, after podman and podman-compose are included in the standard
Debian packages, and update-alternative can switch the standard
docker and the podman, we can unblock 943981 by 840829.

1. apt-get -t disco install buildah podman skopeo slirp4netns containernetworking-plugins
from
deb http://ppa.launchpad.net/projectatomic/ppa/ubuntu disco main

2. apt-get -t bullseye install crun

3. Change runtime = "runc" to runtime = "crun" in
/usr/share/containers/libpod.conf

4. Copy https://github.com/projectatomic/registries/blob/master/registries.fedora
to /etc/containers/registries.conf

Then podman works fine in place of docker as far as I see.

podman-compose, a substitute of docker-compose, can be installed as
pip3 install -U podman-compose.

Best regards,
Ryutaroh Matsumoto