I use some batch scripts in my proxmox installation. They are in cron.hourly and daily checking for virus and ram/CPU load of my LXC containers. An email is send on condition.
What are your tipps or solution without unnecessary load on disc io or CPU time. Lets keep it simple.
Might be a bit more complex than what you want, but I love Prometheus + Alertmanager and a nice sexy Grafana dashboard