A lot of packages simply install systemd units but do not enable them.
Running "systemctl enable" in the maintainer scripts is not really an
option since it is not guaranteed that systemd is installed. We
therefore implement a workaround for wheezy which is supposed to go away
in jessie once we have the necessary tools support in debhelper etc.
What the proposed workaround does is:
- Install a dpkg file trigger for /lib/systemd/system which triggers a
script named /lib/systemd/debian-enable-units every time a package
installs a systemd unit.
- Run this script also upon initial installation of systemd and once on
upgrades from earlier releases.
The script in particular does the following:
- Run "systemctl enable" for each service or socket it finds in
/lib/systemd/system but does that only once, so the administrator can
disable them if wanted.
- Record the state and installed symlinks. When a package shipping
systemd units is uninstalled, we remove those symlinks again.
- Use a blacklist for internal services.
- If systemd is not the active init, it will only create a tag file
and next time we boot with systemd, the script will be run early
during boot. For that we install a service named
debian-enable-units.service which is run in basic.target.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=692150
