Unified cgroup v2 layout Upgrade warning PVE 6.4 to 7.0

[yswery]

Before we upgrade I just want to better understand what the following error means and what it could result in after the upgrade:

WARN: Found at least one CT (174) which does not support running in a unified cgroup v2 layout.
Either upgrade the Container distro or set systemd.unified_cgroup_hierarchy=0 in the Proxmox VE hosts' kernel cmdline! Skipping further CT compat checks.

now for context, I dont see anything special in the config for CT 174:

$ pct config 174

arch: amd64
cores: 2
description: FooBar
features: nesting=1
hostname: z174.foo
memory: 1024
net0: name=eth0,bridge=vmbr0,gw=1.2.3.4,hwaddr=72:B0:22:67:9D:62,ip=3.4.5.6/32,type=veth
onboot: 1
ostype: centos
rootfs: local-lvm:vm-174-disk-0,size=50G
swap: 0

and when I try to search for more global LXC settings, I dont get any cgroup mentions of the terms lxc.cgroup:

$ grep -r "lxc.cgroup" /etc

So what does this warning mean and how does the pve6to7 tests detect which contains are problematic?

Thanks!

 

[fabian]

is this a centos 7 container?

 

[Nefariousparity]

I have the same issue, and yes.

 

[fabian]

https://pve.proxmox.com/wiki/Upgrade_from_6.x_to_7.0#Old_Container_and_CGroupv2
https://pve.proxmox.com/pve-docs/chapter-pct.html#pct_cgroup_compat

 

[Nefariousparity]

Shoot, am I going to be able to upgrade CENTOS 7? LOL.

 

[ness1602]

There is no clear c7>c8 ,only reinstall. Thats in my experience.

 

[Nefariousparity]

Will I be able to boot this CT after upgrade?

 

[Nefariousparity]

Do you add this to nano /etc/default/grub ?

systemd.unified_cgroup_hierarchy=0

 

[fabian]

please read the linked documentations - it contains all the info on how to work around the issue for such legacy guests!

 

[Nefariousparity]

Like this?

 

[Stoiko Ivanov]

Like this?

no - the quoting is wrong...

GRUB_CMDLINE_LINUX_DEFAULT="systemd.unified_cgroup_hierarchy=0 quiet"

usually running update-grub should have warned you...

I hope this helps

 

[yswery]

is this a centos 7 container?

Yes and also happens with Ubunutu 16.X too. Just read the docs and I understand what is happen.

I am curious how the pve6to7 tests detects this since the pct conf doesnt state which version of centos or ubunutu they are

 

[Stoiko Ivanov]

I am curious how the pve6to7 tests detects this since the pct conf doesnt state which version of centos or ubunutu they are

The code is around here:

https://git.proxmox.com/?p=pve-cont...f82747ea558d0398919414945b133dc0;hb=HEAD#l523

put shortly - it mounts the container (or enters it if running) and checks if /sbin/init looks like systemd - if not we assume the container will run, if yes it checks the systemd-version (through the existence of libsystemd-shared-<systemdversion>.so)

I hope this explains it

 

[karnz]

GRUB_CMDLINE_LINUX_DEFAULT="systemd.unified_cgroup_hierarchy=0 quiet"

- Will LXC (centos7) be able to boot successfully after upgraded to PVE7 without modifying grub CMDLINE?
If yes, what will happen on this LXC? Its functions still working as before or any function will be lost/strict?

Or modifying grub is the only way to keep it booting?

 

[ape_sinklair]

How can I fix that after I upgraded to PVE 7.0? Can I add the boot paramter to my Ubuntu 16.10 container without the container running?

 

[ness1602]

Add the parameter to Proxmox host, and the update grub or systemd-boot

 

[Nefariousparity]

So I edited, /etc/default/grub

I changed this line from,
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
to
GRUB_CMDLINE_LINUX_DEFAULT="systemd.unified_cgroup_hierarchy=0 quiet"

I then ran, update-grub. And rebooted the server. However, I am still unable to start CENTOS7 LXC.

 

[yswery]

So I edited, /etc/default/grub

I changed this line from,
GRUB_CMDLINE_LINUX_DEFAULT="quiet"
to
GRUB_CMDLINE_LINUX_DEFAULT="systemd.unified_cgroup_hierarchy=0 quiet"

I then ran, update-grub. And rebooted the server. However, I am still unable to start CENTOS7 LXC.

Try set/add the following to your LXC conf (/etc/pve/lxc/1234.conf for example)

unprivileged: 1

and then try to boot the CT

 

[Nefariousparity]

That worked. OP should mark this as solved.

 

[yswery]

That worked. OP should mark this as solved.

editting the conf and setting the unprivileged is not a real solution to the issue. even PVE docs state this should not be done manually