feat(om2): add native histograms to OpenMetrics2.0 #2634
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Signed-off-by: György Krajcsovits <[email protected]>
Signed-off-by: György Krajcsovits <[email protected]>
Signed-off-by: György Krajcsovits <[email protected]>
Signed-off-by: György Krajcsovits <[email protected]>
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| Numbers MUST be either floating points or integers. Note that ingestors of the format MAY only support float64. The non-real values NaN, +Inf and -Inf MUST be supported. NaN MUST NOT be considered a missing value, but it MAY be used to signal a division by zero. | ||
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| Complex data types MUST contain all information necessary to recreate a Metric Type, with the exception of Created time and Exemplars. |
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This assume we'll have the created timestamp separate from the JSON like data. prometheus/OpenMetrics#285
Signed-off-by: György Krajcsovits <[email protected]>
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Note self: add details how summaries and classic histograms one liners (so not NHCB spans/deltas) fit into it. |
Signed-off-by: György Krajcsovits <[email protected]>
Signed-off-by: György Krajcsovits <[email protected]>
Add semantic conventions about where complex types may occure. Allow empty spans and deltas. Be more precise. Signed-off-by: György Krajcsovits <[email protected]>
Signed-off-by: György Krajcsovits <[email protected]>
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| ##### Exponential buckets | ||
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| Histogram MetricPoints with exponential buckets MUST have a Schema value. The Schema is an 8 bit signed integer between -4 and 127. Schema values between -4 and 127 are also called Standard Schemas. |
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Carrie's document mentions that schema goes from -4 up to 8. I'm a bit confused here, is it 8 or 127?
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I wanted to keep this open ended, 8 is the current implementation maximum. This way we reserve higher resolutions.
Signed-off-by: György Krajcsovits <[email protected]>
Signed-off-by: György Krajcsovits <[email protected]>
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I've just realized that I have not implemented multiple exemplars in the ABNF. I'll do that once I rebase on #2636 |
| @@ -321,14 +392,16 @@ metric = *sample | |||
| metric-type = counter / gauge / histogram / gaugehistogram / stateset | |||
| metric-type =/ info / summary / unknown | |||
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| sample = metricname [labels] SP number [SP timestamp] [exemplar] LF | |||
| sample = metricname [labels] SP value [SP timestamp] [exemplar] LF | |||
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todo, allow multiple exemplars for native histograms
Background
Based on https://github.com/prometheus/proposals/blob/main/proposals/2024-01-29_native_histograms_text_format.md
And OpenMetrics 2.0 WG discussions.
Decisions
To be updated.
Open questions
See OpenMetrics2.0 WG meeting notes tab