By default, when shutting NM down, systemd will kill everything in its
cgroup. But this can cause problems (eg, NM thinking that dhclient
crashed and then taking down an interface that it would otherwise have
left up). Fix this by setting KillMode=process, which tells systemd to
only kill NM itself, and let NM kill its children.
https://bugzilla.redhat.com/show_bug.cgi?id=876218
Since commit 0ce4b6b412
NetworkManager-wait-online.service quits immediately if there is no link yet.
Fix it by removing the '-x' option.
But if we do just that, NM-w-o would add a useless 30 seconds delay in the
case when NM is not running at all.
Solve this by adding a Requisite= dependency on NM.
https://bugzilla.redhat.com/show_bug.cgi?id=710502
1) Don't require NM, but run after it. This allows this service
to be installed without bringing up NetworkManager. Add -x so that
it exits if NM isn't running.
2) Install as a want of network.target, instead of multi-user.target.
This allows us to skip it if nothing requires network.target or the
legacy $network SysV capability.
This pulls in network.target from NetworkManager.service (and not the
other way round), as suggested and agreed on on the systemd ML:
http://lists.freedesktop.org/archives/systemd-devel/2011-March/001692.html
This also introduces an auxiliary service
NetworkManager-wait-online.service that can be used to order a unit
after the point where the network is available. When this is enabled
with "systemd enable NetworkManager-wait-online.service" the unit
network.target will be delayed until the network is up, which is
suitable for synchronizing NFS mounts and similar to it.
https://bugzilla.redhat.com/show_bug.cgi?id=692008
