I found some plugins for OH2 (e.g. this one), but i think they wont work with OH3.
Especially i would like to monitor, if all things are online and maybe some critical temperatures.
Of course i can even (and for some i already do it) could to it with rules an notifications, but monitor the smarthome health in icinga2 would be a great thing, too.
Ok, so I tried it out today by myself and here is the result:
A Icinga2 check plugin to monitor the online/offline state of openhab things.
Its pretty simple but I does exactly what I expected.
Mayme it could be helpful for someone else, too.