LXD 3.0 + cgroup v2 + debian 9

LXD
1

Hi!

I did not find any information on how to do this. LXD builded from source, no snap.

How to switch LXD to cgroup v2 on debian 9? I try this:
/etc/default/grub:
GRUB_CMDLINE_LINUX="cgroup_no_v1=io,memory systemd.legacy_systemd_cgroup_controller=0"

After that there was a catalog:
cgroup on /sys/fs/cgroup/systemd type cgroup2 (rw,nosuid,nodev,noexec,relatime)
and /sys/fs/cgroup/systemd/lxc (magically created somehow)

I manually add IO and memory controllers into it:
echo '+io +memory' > /sys/fs/cgroup/systemd/cgroup.subtree_control

Then when I try to run the container the following happens:

lxc init ... c1
lxc config edit c1
devices:
  root:
    limits.read: 1MB
    limits.write: 1MB
    path: /
    pool: default
    type: disk
lxc start c1
lxc info --show-log c1

lxc c1 20190926152501.663 WARN     cgfsng - cgroups/cgfsng.c:get_hierarchy:204 - There is no useable blkio controller
lxc c1 20190926152501.663 ERROR    cgfsng - cgroups/cgfsng.c:cg_legacy_set_data:2191 - Failed to setup limits for the "blkio" controller. The controller seems to be unused by "cgfsng" cgroup driver or not enabled on the cgroup hierarchy
lxc c1 20190926152501.663 WARN     cgfsng - cgroups/cgfsng.c:__cg_legacy_setup_limits:2228 - Failed to set "blkio.throttle.read_bps_device" to "253:7 1000000"
lxc c1 20190926152501.663 ERROR    start - start.c:lxc_spawn:1723 - Failed to setup cgroup limits for container "c1"

What I must do for correct using cgroup v2 with LXD 3.0?

2

I was also wondering if cgroup v2 are supported or not, I found some PR to suggest it should at least not break but that support was not ready yet. Any official statement about this?

3

That’s about it, LXD will not fail on a cgroupv2-only system, but you also won’t be able to actually use any of the limits at this time.

1 Like
4

Good to know, thanks for the update.

5

Has the situation changed since? I’ve just installed LXD 4.2 from snap on Debian 10 and I’d like to use cgroup v2 only with it.

6

Yeah, LXD has full support for cgroup2 now.

7

And does it provide any specific configuration file/command for cgroup2? Such as lxc config set cgroup2.whatever or something? Or am I supposed to script the required bash commands to find lxc processes IDs and add them to a custom hierarchy?

8

Just use the same limits.* config options as you normally would.