Remove deb_family_systemd_volume from docker_exp

[Sharpie]

The deb_family_systemd_volume logic hardcoded a
--volume /sys/fs/cgroup:/sys/fs/cgroup:ro flag when provisioning
Debian or Ubuntu containers in order to allow SystemD to run.

However, this mount is no longer sufficient when the docker host
is running a Kernel with CGroupsV2 and a SystemD version that defaults
to using systemd.enableUnifiedCgroupHierarchy=true:

docker/for-mac#6073

Ubuntu 22.04 fits these criteria.

In these conditions, --cgroupns=host -v /sys/fs/cgroup:/sys/fs/cgroup:rw
must be used. However, attempting to pass these flags to docker_exp
via docker_run_opts causes docker run to fail due to a conflict
with the hardcoded mount from deb_family_systemd_volume:

stderr:docker: Error response from daemon: Duplicate mount point: /sys/fs/cgroup.

This commit removes the deb_family_systemd_volume logic as:

• CGroup mounts must be configured for any OS family using SystemD, not
  just Debian and Ubuntu.

• The user should be able to exercise full control over mount flags
  via docker_run_opts.

[codecov-commenter]

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[h0tw1r3]

Is this necessary? Ran into the same issue using the docker provisioner with the docker daemon in a nested ubuntu 22 container:

---
default:
  provisioner: docker
  images:
    - litmusimage/debian:11
  vars: "docker_run_opts: ['--tmpfs=/run', '--tmpfs=/run/lock', '-v=/sys/fs/cgroup/puppet.slice:/sys/fs/cgroup/puppet.slice:rw', '--cgroupns=host', '--cgroup-parent=puppet.slice']"

[chelnak]

Did setting those vars in the config work for you?

[h0tw1r3]

@chelnak Indeed. Adding a parent cgroup (which docker will auto-create) and mounting the parent as read-write ends up creating a docker-* specific cgroup underneath puppet.slice for each container without interfering with the hosts cgroup.

[jordanbreen28]

@Sharpie Nice one! could you rebase off main & that should re-kick the CI too.
This change should solve some problems, so hoping to get it in soon!

[jordanbreen28]

Just after taking a further look into this, looks like there is still some references to deb_family_systemd_volume in provision/tasks/docker.rb

provision/tasks/docker.rb

Line 164 in b88830d

deb_family_systemd_volume = if (image =~ %r{debian|ubuntu}) && (image !~ %r{debian8|ubuntu14})

Feel free to lift the changes out of my fork from here :-)

[jordanbreen28]

Closing in favour of #203