リリース

Cortex v1.21.0 graduates several experimental features to stable, fixes multiple PRW2 data corruption and panic bugs, and introduces a new Parquet mode for Store Gateway alongside an Overrides API.

• breakingAudit and update renamed flags before upgrading

  Several flags were renamed: -experimental.ruler.enable-api → -ruler.enable-api, -experimental.alertmanager.enable-api → -alertmanager.enable-api, -distributor.otlp.enable-type-and-unit-labels is now a no-op (consolidated into -distributor.enable-type-and-unit-labels), and parquet cache flags/configs dropped 'queryable' from their names. The users-scanner cleanup-interval became update-interval. Old flags are deprecated but not removed yet — audit your config files and Helm values now, before they disappear in a future release.

• breakingPRW2 data corruption and panic fixes require validation of existing pipelines

  Three separate bugs in the Remote Write V2 handler were fixed: shallow copying of Samples/Histograms caused data corruption, dirty sync.Pool reuse caused index-out-of-range panics, and Symbols backing array wasn't cleared on pool return causing memory leaks. If you're using PRW2, treat this upgrade as mandatory. Validate your ingestion pipeline after upgrading and check that downstream metrics are intact.

• enhancementBucket index is now on by default — verify storage permissions

  The bucket index is enabled by default in this release. If your object storage IAM policies restrict list operations or your Cortex deployment had bucket index disabled intentionally, verify that the bucket index can be written and read correctly post-upgrade. Cortex will generate and maintain the index automatically, but storage permission errors will surface as query failures rather than obvious configuration errors.