We could start cron via the service file ExecStartPost and add a volume?
It works using scp but
using rsync over ssh and allowing webserver to create a file in the root dir we need at least
chown bin:root 9003
I tested with Joomla.
Without the changed owner:
With changed owner the installation is possible:
So from this point of view I’d say it’s a bug as webapps can’t create files but maybe it’s enough to document it.