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How to use Custom Collectors for Histograms #683
Description
When using a histogram metrics we can use the 'observe' method to evaluate which bucket our latest sample will fall in:
E.g.
h1.labels('device-1').observe(value.get('latest_sample'))
->
for i, bound in enumerate(self._upper_bounds):
if amount <= bound:
self._buckets[i].inc(1)
break
However as I am proxying metrics I believe I should be using a Customer Collector and the HistogramMetricFamily which only provides add_metric which seems to just populate all the buckets.
am I supposed to calculate the buckets in my code before writing the metric?
Activity
brian-brazil commentedon Sep 1, 2021
That's how I'd do it, keep in mind that you possibly want to switch the type to GaugeHistogram before sending it on if you're using a custom collector like this.
brian-brazil commentedon Sep 1, 2021
It's a type thing, so may be used by downstream tooling for better hints etc.. If the data is based on counters then it's a Histogram. If it's a snapshot of current state it's a GaugeHistogram.
brian-brazil commentedon Sep 1, 2021
You should create a new Histogram for each collect, otherwise you're risking race conditions.
cunningr commentedon Sep 2, 2021
brian-brazil commentedon Sep 2, 2021
In that case, manually putting together the Histogram's samples is what I'd do.