[systemd-devel] Antw: [EXT] Re: Still confused with socket activation

[Michael Chapman]

On Tue, 9 Feb 2021, Ulrich Windl wrote:
[...]
> As for the drop-ins: I neither know what those are expected to do, not who
> adds them at run time. See "documentation"...

The 50-pacemaker.conf drop-ins are, as their name suggests, created by 
Pacemaker.

Specifically, Pacemaker's systemd resource agent [1] creates a drop-in on 
each Pacemaker-managed systemd service. Consider the situation where both 
Pacemaker and the Pacemaker-managed service are scheduled to be stopped 
(e.g. you're rebooting the entire system). Either you want Pacemaker to 
stop the service itself (and, perhaps, start the service on some other 
node in your cluster), or -- if the pacemaker resource has management 
disabled -- you want the service to be stopped *after* Pacemaker has been 
stopped. Either way, the service needs to be ordered 
Before=pacemaker.service. This is precisely what that drop-in does.

Note that when you're using Pacemaker to manage a systemd service, you 
should not enable the service in the normal way -- that is, the service 
should not be started simply by virtue of it being in the Wants= list of 
multi-user.target. The service is intended to be started and stopped only 
by Pacemaker.

For more help on this drop-in in particular, I think you'd be better off 
contacting the Pacemaker developers.

[1] https://github.com/ClusterLabs/pacemaker/blob/master/lib/services/systemd.c