Hi, I am currently migrating some Docker instances from
overlay2 to make them ready for upcoming Debian Bullseye upgrades (which does not support
aufs any more). Since UCS 5 is based on Debian (I know, it’s still Buster), I also had a look at the situation there.
Most of my UCS 4 systems already use
overlay2, except one which somehow still uses
overlay. I found the UCR variable
docker/daemon/default/opts/storage-driver which is actually set to
overlay on all systems, even if they are using
overlay2. Changing the variable to
overlay2 on that one system still using
overlay and restarting Docker doesn’t change anything. The variable changes
/etc/default/docker, but I think the recommended way to change the storage driver is via
/etc/docker/daemon.json (then it is working at least).
To make it persistent, I added a line
"storage-driver": configRegistry["docker/daemon/default/opts/storage-driver"], to
/etc/univention/templates/files/etc/docker/daemon.json, but this file could be overwritten by an update. It would be nice, if UCS fixes the template and the UCR variable (should there really be a default here, why not just let Docker decide?).