I can see the overall setup was not so bad. When I start the container this way :
gabx@hortensia ➤➤ ~ # systemd-nspawn -bD /dahlia container boots. gabx@hortensia ➤➤ ~ % machinectl -l MACHINE CONTAINER SERVICE dahlia container nspawn 1 machines listed. Machine is listed and I can see a /sys/fs/cgroup/systemd/machine.slice directory
