Bug#943981: Proposal: Switch to cgroupv2 by default

[Ryutaroh Matsumoto]

Hi Michael,

On Sat, 2 Nov 2019 13:54:13 +0100 Michael Biebl <biebl at debian.org> wrote:
> Am 02.11.19 um 00:05 schrieb Noah Meyerhans:
> > I'd like to propose that we switch to cgroupv2 as the default
> > configuration for the bullseye release. This has the potential to
> > impact quite a few packages (notably, it breaks Docker today), so I
>
> Afaics, lxc is also affected, which is quite an issue, given that our CI
> is based on LXC (on stable though, so this would only affect bullseye if
> we decided to stick with v2).

LXC on cgroup v2 seems to have no problem with Debian CI.
Autopkgtest on systemd gave no error as below.
Specifically, related Debian package versions are:

$ grep cgroup /proc/mounts 
cgroup2 /sys/fs/cgroup cgroup2 rw,nosuid,nodev,noexec,relatime,nsdelegate 0 0
$ dpkg-query -W | grep lxc
liblxc1:amd64	1:4.0.2-1~1
lxc	1:4.0.2-1~1
lxc-templates	3.0.4-3

/etc/lxc/default.conf is
lxc.apparmor.profile = generated
lxc.apparmor.allow_nesting = 1
# The above lines are the Debian package default.
lxc.net.0.type = veth
lxc.net.0.link = lxcbr0
lxc.net.0.flags = up
#lxc.mount.auto = cgroup:rw:force
lxc.init.cmd = /sbin/init systemd.unified_cgroup_hierarchy=1

Under the above setup, I ran
# debci setup
and
$ autopkgtest --user debci -o /var/tmp/outdir systemd -- lxc --sudo autopkgtest-unstable-amd64

The result was

autopkgtest [17:43:14]: @@@@@@@@@@@@@@@@@@@@ summary
storage              SKIP Test requires machine-level isolation but testbed does not provide that
upstream             SKIP Test requires machine-level isolation but testbed does not provide that
systemd-fsckd        SKIP Test requires machine-level isolation but testbed does not provide that
timedated            PASS
hostnamed            PASS
localed-locale       PASS
localed-x11-keymap   PASS
logind               PASS
unit-config          PASS
networkd-test.py     PASS
build-login          PASS
boot-and-services    PASS
udev                 PASS
root-unittests       PASS
boot-smoke           PASS

Best regards, Ryutaroh Matsumoto