daemon re{load,start} on configuration change

[Edgar Fuß]

When a configuration file maintained by FAI (we do nightly softupdates) is changed by fcopy, a corresponding daemon may need to be reloaded or restarted.

With daemons with a single configuration file, this may be done in an fcopy postinst file. But I'm currently preparing Icinga 2 clients on our ~150 desktop machines, and the Icinga 2 configuration consists of a dozen files. I don't want to reload multiple times in case several files are being changed at once.

I could build my own scheme for that.

One idea was maintaining a dummy config file I change in the config space whenever I change one or several real config files (and a postinst action for the dummy file), but I would need the dummy file being installed last (which I could force with an extra fcopy call for that file).
Another idea ist touch-ing some trigger file in the postinst action of each config file and then using a hook/script to check the trigger file's time stamp.

But maybe I'm not the first person thinking about this problem and someone else has better ideas or even a working solution.