feat: move suffix handling to scrape time with OTel preserve_names - #1947
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feat: move suffix handling to scrape time with OTel preserve_names#1947zeitlinger wants to merge 3 commits into
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This was referenced Mar 16, 2026
The OM2 writer selection previously activated when any feature flag was set, but there was no way to just enable OM2 without opting into a specific feature. This adds an explicit `enabled` gate (io.prometheus.openmetrics2.enabled) as the single control for OM2 writer selection. Feature flags alone no longer activate OM2. The programmatic `enableOpenMetrics2()` configurator sets enabled=true implicitly, matching its name. Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>
Move metric name suffix handling (_total, _info, unit suffixes) from creation time to scrape time. Each format writer now owns its suffix conventions: - OM1: smart-appends suffixes (skip if already present) - OTel: legacy path strips _total + unit; preserve_names=true passes names through exactly as the user wrote them - Registry detects cross-format name collisions at registration time Key changes: - Remove all reserved metric name suffixes from PrometheusNaming - Store original user-provided name separately from exposition base name in MetricMetadata (originalName vs expositionBaseName) - Add preserve_names config to ExporterOpenTelemetryProperties - Smart-append logic in OM1/protobuf writers for _total and _info - Two-layer collision detection in PrometheusRegistry Closes #1941 Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>
The OM2 writer now uses expositionBaseName instead of appending _total (counters) or unit suffixes. The _info suffix is enforced per the OM2 spec (MUST). Tests updated to verify OM2-specific output rather than asserting identity with OM1. Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>
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Summary
Moves metric name suffix handling (
_total,_info, unit suffixes) from creation time to scrape time. Closes #1941, part of #1942._total+ unit suffix;preserve_names=truepasses names through exactly as the user wrote themKey changes
PrometheusNamingMetricMetadata(originalNamevsexpositionBaseName)preserve_namesconfig toExporterOpenTelemetryProperties_totaland_infoPrometheusRegistry(base name + exposition names)Key table
Counter("events")events_totaleventseventsCounter("events_total")events_totaleventsevents_totalCounter("req").unit(BYTES)req_bytes_totalreq, unitByreq, unitByCounter("req_bytes").unit(BYTES)req_bytes_totalreq, unitByreq_bytes, unitByGauge("events_total")events_totalevents_totalevents_totalTest plan
mise run buildpasses (formatting, static analysis, checkstyle)mise run testpasses (all unit tests)MetricMetadata5-arg constructor and field accessorspreserve_names=truewith units, with unit already in name, and without unitPrometheusRegistryTestcovers collision detectionmise run test-all)mise run acceptance-test)