k3s rootless and cgroups v2

[FlorianLudwig]

Starting k3s in rootless mode fails with failed to find cpuset cgroup (v2). My system does have cgroups v2 enabled though (e.g. /sys/fs/cgroup/cgroup.controllers is present).

Welcoming any pointers how to debug what the root cause is

[brandond]

Which version of k3s are you using? Do you have pure v2 cgroups, or are you in hybrid mode where some of them are still split out?

[FlorianLudwig]

k3s --version
k3s version v1.21.2+k3s1 (5a67e8dc)
go version go1.16.4

On fedora 34.

regarding v2 cgroups - I don't think I have the hybrid on. I didn't know there is a hybrid mode - not exactly sure how to determine if it is on.

[AkihiroSuda]

Please make sure:

• k3s is running as a systemd service https://github.com/k3s-io/k3s/blob/master/k3s-rootless.service
• systemd delegation is enabled https://rootlesscontaine.rs/getting-started/common/cgroup2/

[FlorianLudwig]

Hi @AkihiroSuda,

cgroup delegation:

$ cat /sys/fs/cgroup/user.slice/user-$(id -u).slice/user@$(id -u).service/cgroup.controllers
cpu io memory pids

So indeed cpuset is missing. I followed the instructions there and now I do get:

$ cat /sys/fs/cgroup/user.slice/user-$(id -u).slice/user@$(id -u).service/cgroup.controllers
cpuset cpu io memory pids

Now I do not run into that error anymore but a different one. I am looking into that and will open a new discussion - if needed - as this one is resolved now :) Thanks!