What did you do?

CNCF slack discussion: https://cloud-native.slack.com/archives/C02KR205UMU/p1728397164955929

Expect exemplars for counters/histograms/summaries on first scrape when --enable-feature=exemplar-storage,created-timestamp-zero-ingestion.

I was adding a unit test for NHCB (#14978) and noticed that after calling OpenMetricsParser.CreatedTimestamp , the parser doesn't return exemplars.

This is because when the parser first encounter a metric, it will peek ahead to get the created timestamp here: Next. However Next starts by clearing any exemplars already processed on the series line .

To reproduce the issue, flip the order of exemplars and ct in the test framework:

What did you expect to see?

Expect exemplars for counters/histograms/summaries on first scrape when --enable-feature=exemplar-storage,created-timestamp-zero-ingestion.

What did you see instead? Under which circumstances?

Unit test simulating the first scrape fails. To reproduce the issue, flip the order of exemplars and ct in the test framework:

System information

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Prometheus version

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Prometheus configuration file

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Alertmanager version

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Alertmanager configuration file

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