feat: adds distributor lag counter to push.go #18012
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Rather than relying on recording rules to monitor distributor lag metrics, this PR creates a new prometheus counter in the `push.go` module. This counter allow us to track the difference in time from when a distributor receives a log push request and the ingestion payload's most recent log timestamp. This difference represents how far back in time the logs were captured, giving us insight into distributor "lag". If this counter's values remain steady or increase over time, we know the ingestion agents are falling behind and will eventually start dropping logs. This counter metric has an additional label, "userAgent". This field is extracted from the HTTP request, providing insight into which ingestion agents are being used by a particular tenant. Should we see incoming log ingestion start to fall behind, we can use this label to provide instructions for customers to adjust the agent configuration specifically
…fana/loki into agoss/add-distributor-lag-metric
The OTLP endpoint often experiences an inordinate amount of time skew in the distributor mostRecentLagMs calculation. This filters out any values which are greater than 1B.
paul1r
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Jun 10, 2025
paul1r
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What this PR does / why we need it:
Rather than relying on recording rules to monitor distributor lag metrics, this PR creates a new Prometheus counter in the
push.gomodule.This counter allow us to track the difference in time from when a distributor receives a log push request and the ingestion payload's most recent log timestamp.
This difference represents how far back in time the logs were captured, giving us insight into distributor "lag". If this counter's values remain steady or increase over time, we know the ingestion agents are falling behind and will eventually start dropping logs.
This counter metric has an additional label, "userAgent". This field is extracted from the HTTP request, providing insight into which ingestion agents are being used by a particular tenant. Should we see incoming log ingestion start to fall behind, we can use this label to provide instructions for customers to adjust the agent configuration specifically
Checklist
CONTRIBUTING.mdguide (required)featPRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.docs/sources/setup/upgrade/_index.mddeprecated-config.yamlanddeleted-config.yamlfiles respectively in thetools/deprecated-config-checkerdirectory. Example PR