- Built with Go 1.15, deprecating X.509 CommonName validation and announcing removal of the experimental gRPC API v2 in the next minor release.
- Added new service discovery integrations (Eureka, Hetzner, Kubernetes EndpointSlices) and introduced a per‑scrape target limit.
- Fixed numerous issues across API, PromQL, remote read, TSDB, UI and shutdown handling, with UI enhancements for alerts and rules pages.
2.21.0 / 2020-09-11
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Deprecate non‑true/all values for the stats query parameter on /api/v1/query and /api/v1/query_range, now returning a warning and slated for removal in the next major release.
Updated golang.org/x/text to v0.39.0 and google.golang.org/grpc to v1.82.1, fixing CVE‑2026‑56852 and GHSA‑hrxh‑6v49‑42gf.