Lightweight Web Servers

I’ve been using the excellent Uptime Kuma for my monitoring, but a couple of recent incidents – an external USB mount disappeared on a remote machine, an NVME drive filled up on a different node and stopped backups working because of a configuration error – have made me start to think about more robust monitoring.

The are many great tools for this – Nagios, Prometheus etc. but they are pretty substantial time investments for the excellent power. They can save time series data and display them beautifully. However, all I really want is to add some extra ability to Uptime Kuma.

Uptime Kuma is already pretty great – it can parse a webpage to search for a particular phrase, it can execute searches in popular databases, it can ping, check a docker container is running and all sorts of other tricks – but it can’t check memory use of a service, or if a machine is running out of disk space. Uptime Kuma works in binary – things either pass a check, or they don’t. It does do some nice graphs of ping times, but that’s about all.

I could expose some of this data – disk space free, CPU temp, checking a mount is working – pretty easily in a little Node endpoint. But it thinking about this, it made me wonder what the overhead of running Node (probably with Express) to carry out this menial task might be. I was thinking that the alternatives would be to use python/flask, or just to write it in C or Golang.

Whilst searching for answers about this, I found this excellent article from Bence Cotis. It turns out, that for very low loads (I’ll probably hit these endpoints once every five minutes) C is a bit better, but probably not (in my opinion) worth the hassle. I’ll stick to Node.