How to create Histogram metrics?

[bruno....@gmail.com]

Hi all,

I started using Prometheus a couple of ago to monitor a few set of server used for experimental work (hence a newbie in the community).

NodeExporter provides a great amount of metrics for that but from what I have seen none of these are Histogram.

As a simple example I would like to collect data on the amount of incidents where the cpu/ram/disk utilization is above a certain threshold.

I'm not sure if recording rules are supposed to be used to create these metrics as there is already a specific metric type for Histogram.

I would like to know if there is any example which I could base on for my use case. 

Also, what would be the best practice to implement this - is recording rules a good approach?

Best regards,

Bruno.

[Julius Volz]

Hi there,

Usually you would create one of the client libraries (the one for your language) to create a histogram. For an example in Go, click the "Example" text under https://godoc.org/github.com/prometheus/client_golang/prometheus#Histogram.

Or see for example this histogram in a demo service: https://github.com/juliusv/prometheus_demo_service/blob/master/api.go#L16-L25

When it gets exposed over HTTP, it's simply one time series per less-than-or-equals ("le") bucket. If you have a single concrete acceptable threshold, then you maybe only need one bucket below and one bucket above the threshold to see how many requests are below/above the threshold. See also Apdex score calculation with Prometheus: https://prometheus.io/docs/practices/histograms/#apdex-score

If you want to see a concrete example of how a histogram looks in the text format, see the text format specification: https://prometheus.io/docs/instrumenting/exposition_formats/#text-format-details - but a client library will usually do this for you.

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[Julius Volz]

On Fri, Nov 25, 2016 at 6:14 PM, Julius Volz <juliu...@gmail.com> wrote:

Usually you would create one of the client libraries (the one for your 

s/you would create/you would use/ 

[Bruno Grazioli]

Hi Julius,

The example in the demo service is exactly what I was looking for!

Thanks for the help.

BR,

Bruno.