:warning: This release contains potential breaking change if you use experimental zstd support introduce in #1496 :warning:

Experimental support for zstd on scrape was added, controlled by the request Accept-Encoding header. It was enabled by default since version 1.20, but now you need to add a blank import to enable it. The decision to make it opt-in by default was originally made because the Go standard library was expected to have default zstd support added soon, https://github.com/golang/go/issues/62513 however, the work took longer than anticipated and it will be postponed to upcoming major Go versions.

e.g.:

import (
  _ "github.com/prometheus/client_golang/prometheus/promhttp/zstd"
)

• [FEATURE] prometheus: Add new CollectorFunc utility #1724
• [CHANGE] Minimum required Go version is now 1.22 (we also test client_golang against latest go version - 1.24) #1738
• [FEATURE] api: WithLookbackDelta and WithStats options have been added to API client. #1743
• [CHANGE] :warning: promhttp: Isolate zstd support and klauspost/compress library use to promhttp/zstd package. #1765

All Changes

• build(deps): bump golang.org/x/sys from 0.28.0 to 0.29.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1720
• build(deps): bump google.golang.org/protobuf from 1.36.1 to 1.36.3 by @dependabot in https://github.com/prometheus/client_golang/pull/1719
• Update RELEASE.md by @bwplotka in https://github.com/prometheus/client_golang/pull/1721
• chore(docs): Add links for the upstream PRs by @kakkoyun in https://github.com/prometheus/client_golang/pull/1722
• Added tips on releasing client and checking with k8s. by @bwplotka in https://github.com/prometheus/client_golang/pull/1723
• feat: Add new CollectorFunc utility by @Saumya40-codes in https://github.com/prometheus/client_golang/pull/1724
• build(deps): bump google.golang.org/protobuf from 1.36.3 to 1.36.4 by @dependabot in https://github.com/prometheus/client_golang/pull/1725
• build(deps): bump the github-actions group with 5 updates by @dependabot in https://github.com/prometheus/client_golang/pull/1726
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1727
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1731
• build(deps): bump golang.org/x/sys from 0.29.0 to 0.30.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1739
• build(deps): bump google.golang.org/protobuf from 1.36.4 to 1.36.5 by @dependabot in https://github.com/prometheus/client_golang/pull/1740
• Cleanup dependabot config by @SuperQ in https://github.com/prometheus/client_golang/pull/1741
• Upgrade Golang version v1.24 by @dongjiang1989 in https://github.com/prometheus/client_golang/pull/1738
• build(deps): bump the github-actions group with 2 updates by @dependabot in https://github.com/prometheus/client_golang/pull/1742
• Merging 1.21 release back to main. by @bwplotka in https://github.com/prometheus/client_golang/pull/1744
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1745
• Add support for undocumented query options for API by @mahendrapaipuri in https://github.com/prometheus/client_golang/pull/1743
• exp/api: Add experimental exp module; Add remote API with write client and handler. by @bwplotka in https://github.com/prometheus/client_golang/pull/1658
• exp/api: Add accepted msg type validation to handler by @saswatamcode in https://github.com/prometheus/client_golang/pull/1750
• build(deps): bump the github-actions group with 5 updates by @dependabot in https://github.com/prometheus/client_golang/pull/1751
• build(deps): bump github.com/klauspost/compress from 1.17.11 to 1.18.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1752
• build(deps): bump github.com/google/go-cmp from 0.6.0 to 0.7.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1753
• exp: Reset snappy buf by @saswatamcode in https://github.com/prometheus/client_golang/pull/1756
• Merge release 1.21.1 to main. by @bwplotka in https://github.com/prometheus/client_golang/pull/1762
• exp: Add dependabot config by @saswatamcode in https://github.com/prometheus/client_golang/pull/1754
• build(deps): bump peter-evans/create-pull-request from 7.0.7 to 7.0.8 in the github-actions group by @dependabot in https://github.com/prometheus/client_golang/pull/1764
• promhttp: Isolate zstd support and klauspost/compress library use to promhttp/zstd package by @liggitt in https://github.com/prometheus/client_golang/pull/1765
• Cut 1.22.0-rc.0 by @kakkoyun in https://github.com/prometheus/client_golang/pull/1768

New Contributors

• @Saumya40-codes made their first contribution in https://github.com/prometheus/client_golang/pull/1724
• @mahendrapaipuri made their first contribution in https://github.com/prometheus/client_golang/pull/1743
• @liggitt made their first contribution in https://github.com/prometheus/client_golang/pull/1765

Full Changelog: https://github.com/prometheus/client_golang/compare/v1.21.1...v1.22.0-rc.0