[pkg-lxc-devel] Bug#992255: openvpn fails in a container (missing cgroup2 support)

[Jean-Michel Vourgère]

Package: lxc-templates
Version: 3.0.4-5
Severity: normal
Affects: openvpn

Dear Maintainer,

After upgrading to bullseye, my container with openvpn failed to start.

The syslog error message is:
ERROR: Cannot open TUN/TAP dev /dev/net/tun: Operation not permitted (errno=1)
and indeed "cat /dev/net/tun" fails with that same error.

I traced the problem to cgroup2 migration.

Adding
lxc.cgroup2.devices.allow = c 10:200 rwm
in my container config file fixed the issue.

I believe cgroup2 support should be added generally in
/usr/share/lxc/config/debian.common.conf
with keys for both cgroup1 and cgroup2 in a way that is similar to 
/usr/share/lxc/config/common.conf

Please add cgroup2 support.

Thank you
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