Can we use prometheus to monitor a state(member variable) in a system

[Jeivardan]

Consider an example my system has an object called chamber and one of its properties is pressure and I wish to monitor this pressure. Is it possible using prometheus?

Regards,

Jeivardan V

[Tom Black]

you need to customize a plugin IMO. prometheus itself is
Language-independent.

regards.

[Jeivardan]

What do you mean by plugin IMO can explain in detail?

[Tom Black]

Hi

Jeivardan wrote:
> What do you mean by plugin IMO can explain in detail?

Please check the documentation:
https://prometheus.io/docs/instrumenting/writing_exporters/

regards.

[Jeivardan]

Hi tom,

So what I understood from your reply is that we can monitor any state variables in a class or in a system using prometheus and for that we should write exporters? Is that right?

Regards,

Jeivardan V

[Brian Candler]

Yes, and there are multiple ways to do that.

Ideally you would integrate exporter capability into your existing application, using one of the client libraries.

You can run a standalone exporter like statsd_exporter, and send messages to it to update the state that it exposes.

At worst you can just write metrics into a file in the exposition format, then serve them using node_exporter's textfile collector, or even just a plain web server.

[Jeivardan]

And also I have another question.

Consider my application has 5 states(enums) and that change over time Can I monitor those kind of things.Any idea that which metrics(like gauge) can I use in that case. And another example might be consider my application has a state called voltage and also has min and Max threshold and I wish to monitor such state and create alerts whether gauge is the correct one to measure such kind(voltage, pressure etc ..).

Regards,

Jeivardan V

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[Brian Candler]

You can monitor anything that can be represented as a float64 numeric value.  The meaning and units of those metrics is up to you - whether it be Volts or N/m^2 or whatever.

For enums it's conventional to have a separate timeseries for each choice:

mymetric{state="foo"} 0
mymetric{state="bar"} 1
mymetric{state="baz"} 0

mymetric{state="qux"} 0

You could instead have a single timeseries with different numeric values for each enum choice - and some tools like Grafana support mapping of those values to text labels - but it's generally less convenient.

Prometheus can generate alerts from alerting rules, which are basically PromQL expressions which are evaluated at repeated intervals and raise an alert if a non-empty set of timeseries is returned.  These are delivered to a separate AlertManager component which groups and delivers alerts.

[Jeivardan]

Thank you for your responses.

Regards,

Jeivardan V

[Jeivardan]

Hi all,

I have another doubt. In my system I to record every state change of a variable can prometheus support this or promethus only save sample data?

Regards,

Jeivardan

[Jeivardan]

*I wish to

[Brian Candler]

On Thursday, 17 September 2020 04:46:21 UTC+1, Jeivardan wrote:

In my system I to record every state change of a variable can prometheus support this or promethus only save sample data?

Prometheus samples data periodically - this is called "scraping".  You can configure the scrape interval, but you can only provide one data point per timeseries per scrape.

This is fundamental to prometheus' design.  Prometheus contains a timeseries database (TSDB), but you don't have direct write access to that TSDB.

There are other TSDB's that do let you write ("push") arbitrary data.  Examples include TimescaleDB, InfluxDB, VictoriaMetrics.