otlptranslator: filter __name__ from OTLP attributes to prevent duplicates#17917
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aknuds1 merged 2 commits intoprometheus:mainfrom Jan 24, 2026
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ArthurSens
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Oh wow, did you see that actually happening? 😱
Either way, it's a good bugfix. LGTM! Just one small suggestion
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@ArthurSens No, it's just a defensive fix. Mainly to rule out the OTLP translation as a possible cause of this type of bug. |
…cates
OTLP metrics can have a __name__ attribute which, when combined with the
metric name passed via extras, creates duplicate __name__ labels. This
causes TSDB compaction failures with errors like:
corruption detected when writing postings to index: label "__name__"
has 7479 uses, but maxPostings is 7477
The fix filters reserved label names (currently just __name__) from OTLP
attributes in all data point handlers: gauge, sum, histogram, exponential
histogram, custom buckets histogram, and summary.
Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
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Add a subtest to TestPrometheusConverter_createAttributes to verify that __type__ and __unit__ attributes in OTLP data are correctly overwritten by auto-generated labels from metadata when EnableTypeAndUnitLabels is enabled. Also rename TestCreateAttributes to TestPrometheusConverter_createAttributes for consistency, and move TestOTLPNameAttributeFiltered into a subtest. Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>
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Which issue(s) does the PR fix:
OTLP metrics with a
__name__attribute may create duplicate__name__labels.Does this PR introduce a user-facing change?
Description
In data point handlers, all calls to
createAttributespassnilforignoreAttrs, allowing__name__attributes from OTLP data to pass through. Since__name__is also added via theextrasparameter, this creates duplicate labels.This PR adds a
reservedLabelNamesslice and updates all data point handlers to filter these reserved labels:addGaugeNumberDataPointsaddSumNumberDataPointsaddHistogramDataPointsaddSummaryDataPointsaddExponentialHistogramDataPointsaddCustomBucketsHistogramDataPointsIncludes regression tests verifying that only one
__name__label exists and the correct metric name is used.