I received an error while trying to launch a Nomad job with the Exec driver on my cluster of Raspberry Pi 4’s. Something about CGroups.
The Pi4 does not enable the memory cgroup by default, which the exec driver requires to execute correctly. To validate this assertion:
$ cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
...
memory 0 99 0
...
To fix, on each node, an update to /boot/cmdline.txt needed to be made, and a reboot needed to occur.
Append the following to the /boot/cmdline.txt:
cgroup_enable=memory
After rebooting, see that the memory cgroup is enabled:
$ cat /proc/cgroups
#subsys_name hierarchy num_cgroups enabled
...
memory 0 99 1
...