Prometheus and Grafana are genuinely excellent — and genuinely overkill for a handful of VPS instances. An honest, side-by-side look at Netdata, Uptime Kuma, Beszel, a DIY cron script, and Brimfull.

A copy-pasteable bash script that checks disk, CPU, and memory on a schedule and alerts you before something breaks — plus where this kind of script quietly turns into a maintenance burden.