Hi all, thought I would share this, it's a super-simple-super-lightweight (9KB) plugin that will shutdown your server at any given time - as configured by an even simpler XML file.
The plugin will give all online players 1 minute notice via a waning message, accompanied by audio alert.
Complete XML syntax for setting.xml is as follows. So you just need to edit the two integers to specify your time. Can't be simpler right?
You will then need to use Task Scheduler (or your Linux equivalent) to start the server back up approx 2 minutes after the scheduled shutdown time (The actual shutdown event starts 1 minute after the scheduled time).
Unfortunately startups can't be done with plugins as the JVM they are running in are killed during the process of the shutdown.
Source code and walk-through is also available on Medieval Realms website (almost all up and hopefully making sense).