I was reading a homelab discussion about NUTs (Network UPS Tools) that left me scratching my head and wondering "…why? Is complexity for complexities sake part of homelabs? Isn’t this a huge overkill for one machine? Just…use a UPS? "
So, you don’t need to run any software at all on a host on a UPS. You don’t need NUT or anything similar. You can just plug a PC into a UPS.
However, traditionally, the purpose of a UPS isn’t “just power a machine through an extended outage”. It’s to provide enough time to cleanly shut down a machine. Save work, and—once upon a time, filesystems that weren’t cleanly unmounted could become corrupt—unmount filesystems.
It can also provide time for something like a backup generator, if you have something like that up. The UPS may only have enough juice to run the PC for a few minutes. If you look at traditional UPS units, they have very limited amounts of time that they can keep a PC running. They aren’t aimed at the “whole house multi-day keep things running” capability that some lithium ion battery setups are these days.
So traditionally, one would have software on a machine that takes some action, like shutting it down cleanly, when the battery gets low.
If what you have a UPS for is to keep a PC running through momentary power interruptions, and you don’t care about, say, remotely monitoring power status, then, sure. NUT isn’t necessary. Same thing if you just want to provide a short amount of buffer time to let a generator that comes on automatically in an outage fire up.
But if you want remote monitoring of power status or you want hosts to shut down cleanly, then it may be useful. For some people, that’s the reason that they have a UPS at all.