I've been trying to recall the name of remind! Used it years ago, great for conditional dates (bin collections especially, every other Monday, except public holidays, then move to Tuesday). I can't recall the syntax but really useful.

Have not tried wyrd, I just emailed myself daily with the calendar. Will take a look

Thank you internet stranger!

Personally I opt for zabbix. But I've been working with it for years. Simple deployment, lots of support, just works.

I'm about quarter of the way through 2, really enjoying it.

Same, I emailed the Devs yesterday suggesting a Lemmy port. Guess they already had the memo and worked on it.