Maybe it's well known but I just came across journalctl-desktop-notification and I find it very useful so I thought I'd mention it. It's basically a bash script that monitors systemd's journal and pops up a notification when there are warnings or errors (or anything else you want to make it catch besides the default config).
What makes it so useful for the selfhoster is that it can monitor the journal on hosts your user has ssh access to with key authentication (set up in 2s with 'ssh-copy-id').
So case in point, this just popped up:
My reverse proxy can't renew certs, that's bad. For some reason netdata didn't catch it, and the service didn't trigger a system email that would have been forwarded to my smtp. Uptime kuma would have caught it when I would have had only a few days to fix it, but this caught it immediately, and I have 52 days to figure it out.
So you install that on your daily driver and you get these notifications on your desktop. They only have packages for Arch and Gentoo but the thing is just a batch script and a systemd unit. So to install anywhere you just download the "source", extract it, cd to it, and run 'sudo cp -r usr etc /' which is exactly what the Arch package does (line 22).
Just a nifty little tool I wanted to share in case others haven't heard of it.
Edit: I made .deb and .rpm packages so it's a lot easier to install now :)
There is still a good reason to know about problems early. Without any monitoring you will find out about problems exactly in that moment when you what to use the service that doesn't work. Sometimes you need something quick and you don't have time to debug and fix in that moment. If you get an alert early you can decide to fix it right away or in a few hours or tomorrow.
What do you need quick? I have a Minecraft server, a wiki for random stuff, a shopping list, a calendar sync, photo hosting, a media server and probably some other shit on there.
I can think of many situations where I'd want those quickly, but need I don't anything.
Calendar sync? I learned that Nextcloud went to shit again when I missed an event added by my spouse to the shared calendar. Pretty important to me.
You don't need something ever. Sometimes you just want something because the alternative is realy bad. I don't need to eat. I want to eat because I don't want to starve.
I want to watch a movie with my partner at the agrees time because otherwise they will be mad. I want to access my digitalized documents to send a letter in time because otherwise I will have to pay late fees. I want to access my gameserver because that's the one time a week I get to have fun with my friends from my college time.
There are many situations where I'd rather do the thing I want instead of doing maintenance.
Yep and I have less time for all these things when I spend the time setting up monitoring.
Fixing takes the same time either way. But I barely ever have to touch my setup anyway, because usually ot doesn't just break randomly.