Feasibility for a new use by a new user


I’m new, I’m looking to find the right solution to monitor production machines and computer servers.

I’m looking for Prometheus + Grafana. First I would have to read production datas data in MODBUS TCP, the activity of Apache servers and the prometheus server of course.

If I am interested in any advice and opinions in this goal, I am reassured by the documentation where I seem to find what I need to progress.

A fundamental question persists :
I would like to note events on dates or on date ranges.
“On 03/30/2022 a beginner asks stupid questions”
“from 30/03/2022 12:00 to 1/04/2022 16:00 the coffee machine was broken” and see this on graph.
Prometheus seems to only handle timestamp/value pairs (float64) and I couldn’t find anything with Grafana.
How can I manage such recordings (and annotations on Grafana graphics)? Is this possible?

Thanks in advance for your help.

Annotations of events are not something done in Prometheus itself. Prometheus can generate alerts, and you can do various things wit this.

Annotations is a separate feature in Grafana. The Grafana docs have the info on this.

For MODBUS, the modbus_exporter will do the trick.

For Apache, I recommend using mtail to extract metrics from logs, as Apache itself has almost no useful data. Related, I can recommend https://caddyserver.com/ as a much better replacement for Apache. Caddy has native support for Prometheus.

Great for annotations, I wasn’t looking in the right place. I just have to find where Grafana records this.

Great for the modbus_exporter too.

I take advantage of this example of modbus export for another question:
If a modbus TCP server is broken (no response) or if there is another problem with modbus exporter, what is the right way to handle the problem? to detect it? to debug it?

Thanks for all.