Have you played around with Grafana? It really is quite simple if you have prometheus already working.

For a home lab environment you dont even need to use prometheus-alertmanager. Grafana can handle alerts as well.

Grafana also has hundreds of pre-made dashboards you can import. Node monitoring is quite straightforward.

Assuming you have prometheus good to go, all you need to do is go to Grafana - Datasources, create a new datasource, point to your prometheus instance.

Then you can import the dashboards you want.

Now you can setup your alerts - you can use SMTP, telegram, slack among others for your notifications.

Is there a self hosted OpenTelemetry consumer?

The easiest solution I found and use is Beszel.

https://github.com/henrygd/beszel

Just a hub with the most important stats and some simple agents on the servers.

ICINGA/NAGIOS? you can even feed data already collected by Prometheus to it if you want.

SNMP does what you want. You just need a good monitoring solution that's not as involved as Prometheus+grafana (I feel you, I've been there)

I really enjoy PRTG, but it's way too expensive for a home lab, still throwing it out there if you feel like you have money to burn.

I hear good word about libreNMS, it's next on my list when my PRTG licence runs out.

Be warned that monitoring is ultimately a fickle thing; what you don't write in yaml config for grafana, you get to dig through obscure SNMP libs to find out (though I find that's easier for me, ymmv) for other tools.

I recommend against: nagios (I like it but if you hate Prometheus it's definitely not for you), checkmk (throw checkmk into the sun please it just fucking sucks), cacti (NO!), solar winds (why?)

if you feel like you want to become a datacenter admin: zabbix scales very very well, both in performance and ease of admin against hundreds of servers, but it's overkill for a home lab, and it can get you lost in configs for hours.

I'm currently using InfluxDB + Telegraf + Grafana combination to monitor Linux systems and k3s pods. It's basically same as Prometheus, but InfluxDB uses push model, which makes it easier to develop tools for collecting custom time series data.

For alerts and dashboards, I think Grafana is the simplest and most hassle free solution available at the moment.

Zabbix
https://www.zabbix.com/

Netdata
https://www.netdata.cloud/

Nagios
https://www.nagios.org/

I mean, you get a lot of advantages from fluffy pretty systems. But extracting data from df and systemctl and curling it into telegram is going to be like a 10 line bash script called from a one-line cron job.

I pump a lot of complicated metrics through Prometheus / grafana to get graphs and history.

Most of my critical stuff is still in Nagios and instead of using nagios standardized plugins I just query the operating system directly in bash.

Edit: found better resources

https://linuxhandbook.com/syslog-guide/

https://github.com/linuxserver/docker-syslog-ng

That should be a good place to start. Syslog will do what you want.