Different cgroups versions in arm64/amd64 for 'default' image

I’ve just updated our Linux images to use ‘default’ to avoid issues with the upcoming image deprecations. Now my tests fail on arm64, but not amd64.

When I connect to the tests I see the following behaviour which suggests that one is running cgroup1 and the other cgroup2.

On amd64

$ docker run --rm -it --memory=512Mb ubuntu:22.04 bash

root@95e8a477bb2c:/# cat /sys/fs/cgroup/cpu.max

max 100000

On arm64

$ docker run --rm -it --memory=512Mb ubuntu:22.04 bash

root@f5bdb9945390:/# cat /sys/fs/cgroup/cpu.max

cat: /sys/fs/cgroup/cpu.max: No such file or directory

I see the same behaviour with 20.04 as well. Is this an issue with the new default images, or with the ubuntu images?

This worked fine with ubuntu-2204:2022.07.1 so I thought I’d check here.