@jsalvador @cr0n0s #Nagios is fantastic. I've been using it forever. Every once in a while I look at the shiny new thing everyone is raving about and usually find that it doesn't do everything Nagios does.
Setting up Nagios is also quite straightforward, though it may take a bit of getting used to.
Nagiosgraph is a quick way to get useful visualisations as well. The graphs aren't as pretty as graphana's but it's a lot faster to set up, and has much lower system requirements.