Previously generated units were always placed at the end of the search
path. With this change there will be three unit dirs instead of one, to
place generated entries at the beginning, in the middle and at the end
of the search path:
beginning: for units that need to override all configuration, regardless
of user or vendor. Example use: system-update-generator uses this to
temporarily redirect default.target.
middle: for units that need to override vendor configuration, but not
vendor configuration. Example use: /etc/fstab should override vendor
supplied configuration (think /tmp), but should not override native user
configuration.
end: does not override anything but is available as well. Possible usage
might be to convert D-Bus bus service files to native units but allowing
vendor supplied native units to win.
UnitPath= is also writable via native units and may be used by generators
to clarify from which file a unit is generated. This patch also hooks up
the cryptsetup and fstab generators to set UnitPath= accordingly.
This should help making the boot process a bit easier to explore and
understand for the administrator. The simple idea is that "systemctl
status" now shows a link to documentation alongside the other status and
decriptionary information of a service.
This patch adds the necessary fields to all our shipped units if we have
proper documentation for them.
systemctl called LoadUnit, GetUnit, GetAll in this order to get the properties.
It is useless to load units explicitly, because it won't ensure anything. The
unit may be freed immediately by the garbage collector.
It is unnecessary to call GetUnit, because systemctl can easily translate the
unit name to DBus path by itself.
GetAll will load the unit if necessary.
In some cases the main/control PID of a service can be outside of the
services cgroups (for example, if logind readjusts the processes'
cgroup). In order to clarify this for the user show the main/control PID
in the cgroup tree nonetheless, but mark them specially.
Kay Sievers