PrometheusReceiver Ignores Timeseries (Histogram and Summary) Metrics without "_sum" counter

[sankala-dremio]

Currently, when Timeseries data is scraped by Prometheus Scraper, it expects bucketed data and two counters along with those buckets - _count and _sum.
Some frameworks do no capture the _sum and hence do not produce the _sum counter in the Prometheus Exp format. While the Scraper and Prometheus work fine and display appropriate graphs without this counter, Prometheus receiver on the other hand expects this counter to be present for all time series metrics and if not present silently ignores the metric and associated datapoints.

Is this really the desired behavior for PrometheusReceiver?

[jmacd]

What does the real Prometheus server do in this case? We should do what it does, I think.

[sankala-dremio]

Prometheus Server accepts and renders time series metric irrespective of presence of "_sum". Hence prometheus receiver should at least do the same. I can submit a PR for this change if agreed upon this behavior.

[rakyll]

@odeke-em is working on this.

[jmacd]

Brian B. stated in today's meeting that Prometheus will accept Summaries without "_cnt" as well as without "_sum" and/or without any quantiles.

[odeke-em]

The Prometheus receiver wasn’t necessarily the problem but it was the exporter as I showed in open-telemetry/opentelemetry-collector#2661 (comment) and fixed by PR open-telemetry/opentelemetry-collector#2900

Let’s close this issue as the change to the collector just got merged. Thanks everyone for the discussion.

[bogdandrutu]

@odeke-em it was also this open-telemetry/opentelemetry-collector#2812 that helped

[odeke-em]

Gotcha, thank you @bogdandrutu for the follow up.