:warning: This release contains potential breaking change if you upgrade github.com/prometheus/common to 0.62+ together with client_golang. :warning:

New common version changes model.NameValidationScheme global variable, which relaxes the validation of label names and metric name, allowing all UTF-8 characters. Typically, this should not break any user, unless your test or usage expects strict certain names to panic/fail on client_golang metric registration, gathering or scrape. In case of problems change model.NameValidationScheme to old model.LegacyValidation value in your project init function.

• [BUGFIX] gocollector: Fix help message for runtime/metric metrics. #1583
• [BUGFIX] prometheus: Fix Desc.String() method for no labels case. #1687
• [ENHANCEMENT] prometheus: Optimize popular prometheus.BuildFQName function; now up to 30% faster. #1665
• [ENHANCEMENT] prometheus: Optimize Inc, Add and Observe cumulative metrics; now up to 50% faster under high concurrent contention. #1661
• [CHANGE] Upgrade prometheus/common to 0.62.0 which changes model.NameValidationScheme global variable. #1712
• [CHANGE] Add support for Go 1.23. #1602
• [FEATURE] process_collector: Add support for Darwin systems. #1600 #1616 #1625 #1675 #1715
• [FEATURE] api: Add ability to invoke CloseIdleConnections on api.Client using api.Client.(CloseIdler).CloseIdleConnections() casting. #1513
• [FEATURE] promhttp: Add promhttp.HandlerOpts.EnableOpenMetricsTextCreatedSamples option to create OpenMetrics _created lines. Not recommended unless you want to use opt-in Created Timestamp feature. Community works on OpenMetrics 2.0 format that should make those lines obsolete (they increase cardinality significantly). #1408
• [FEATURE] prometheus: Add NewConstNativeHistogram function. #1654

All commits

• Merge release-1.20 to main by @bwplotka in https://github.com/prometheus/client_golang/pull/1582
• gocollector: Tiny fix for help message with runtime/metrics source. by @bwplotka in https://github.com/prometheus/client_golang/pull/1583
• ci: bump dagger to the latest version by @marcosnils in https://github.com/prometheus/client_golang/pull/1588
• Merge release-1.20 back to main by @ArthurSens in https://github.com/prometheus/client_golang/pull/1593
• Update linting by @SuperQ in https://github.com/prometheus/client_golang/pull/1603
• Update supported Go versions by @SuperQ in https://github.com/prometheus/client_golang/pull/1602
• build(deps): bump golang.org/x/sys from 0.22.0 to 0.24.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1611
• build(deps): bump github.com/prometheus/common from 0.55.0 to 0.57.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1612
• changed the name of all variables with min/max name by @parthlaw in https://github.com/prometheus/client_golang/pull/1606
• Update Dagger and build. by @SuperQ in https://github.com/prometheus/client_golang/pull/1610
• build(deps): bump github/codeql-action from 3.25.15 to 3.26.6 in the github-actions group across 1 directory by @dependabot in https://github.com/prometheus/client_golang/pull/1614
• examples: Improved GoCollector example. by @bwplotka in https://github.com/prometheus/client_golang/pull/1589
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1615
• process_collector: fill in most statistics on macOS by @mharbison72 in https://github.com/prometheus/client_golang/pull/1600
• :zap: http client defer CloseIdleConnections by @cuisongliu in https://github.com/prometheus/client_golang/pull/1513
• Set allow-utf-8 in Format during tests to avoid escaping. by @ywwg in https://github.com/prometheus/client_golang/pull/1618
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1622
• Merge Release 1.20 back to main by @ArthurSens in https://github.com/prometheus/client_golang/pull/1627
• examples: Add custom labels example by @ying-jeanne in https://github.com/prometheus/client_golang/pull/1626
• Refactor default runtime metrics tests for Go collector so that default runtime metric set autogenerates by @vesari in https://github.com/prometheus/client_golang/pull/1631
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1628
• process_xxx_memory statistics for macOS (cgo) by @mharbison72 in https://github.com/prometheus/client_golang/pull/1616
• build(deps): bump github.com/klauspost/compress from 1.17.9 to 1.17.10 by @dependabot in https://github.com/prometheus/client_golang/pull/1633
• build(deps): bump golang.org/x/sys from 0.24.0 to 0.25.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1632
• process_collector: Add Platform-Specific Describe for processCollector by @ying-jeanne in https://github.com/prometheus/client_golang/pull/1625
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1635
• build(deps): bump the github-actions group with 4 updates by @dependabot in https://github.com/prometheus/client_golang/pull/1634
• Optionally print OM created lines by @ArthurSens in https://github.com/prometheus/client_golang/pull/1408
• process_collector: merge wasip1 and js into a single implementation by @ying-jeanne in https://github.com/prometheus/client_golang/pull/1644
• Merge release 1.20 to main by @bwplotka in https://github.com/prometheus/client_golang/pull/1647
• Add Arianna as maintainer 💪 by @ArthurSens in https://github.com/prometheus/client_golang/pull/1651
• test add headers round tripper by @Manask322 in https://github.com/prometheus/client_golang/pull/1657
• build(deps): bump github.com/klauspost/compress from 1.17.10 to 1.17.11 by @dependabot in https://github.com/prometheus/client_golang/pull/1668
• build(deps): bump golang.org/x/sys from 0.25.0 to 0.26.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1669
• build(deps): bump github.com/prometheus/common from 0.59.1 to 0.60.1 by @dependabot in https://github.com/prometheus/client_golang/pull/1667
• build(deps): bump google.golang.org/protobuf from 1.34.2 to 1.35.1 by @dependabot in https://github.com/prometheus/client_golang/pull/1670
• Optimize BuildFQName function by @jkroepke in https://github.com/prometheus/client_golang/pull/1665
• fix: use injected now() instead of time.Now() in summary methods by @imorph in https://github.com/prometheus/client_golang/pull/1672
• process_collector: avoid a compiler warning on macOS (fixes #1660) by @mharbison72 in https://github.com/prometheus/client_golang/pull/1675
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1674
• build(deps): bump the github-actions group across 1 directory with 3 updates by @dependabot in https://github.com/prometheus/client_golang/pull/1678
• [chore]: enable perfsprint linter by @mmorel-35 in https://github.com/prometheus/client_golang/pull/1676
• Duplicate of #1662 by @imorph in https://github.com/prometheus/client_golang/pull/1673
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1679
• chore: enable usestdlibvars linter by @mmorel-35 in https://github.com/prometheus/client_golang/pull/1680
• Add: exponential backoff for CAS operations on floats by @imorph in https://github.com/prometheus/client_golang/pull/1661
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1683
• [1617] Add ConstnativeHistogram by @shivanthzen in https://github.com/prometheus/client_golang/pull/1654
• fix: replace fmt.Errorf with errors.New by @kakkoyun in https://github.com/prometheus/client_golang/pull/1689
• Add codeowners by @kakkoyun in https://github.com/prometheus/client_golang/pull/1688
• fix: add very small delay between observations in TestHistogramAtomicObserve by @imorph in https://github.com/prometheus/client_golang/pull/1691
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1692
• Fix: handle nil variableLabels in Desc.String() method and add tests for nil label values by @kakkoyun in https://github.com/prometheus/client_golang/pull/1687
• examples: Follow best practices and established naming conventions by @lilic in https://github.com/prometheus/client_golang/pull/1650
• setup OSSF Scorecard workflow by @mmorel-35 in https://github.com/prometheus/client_golang/pull/1432
• build(deps): bump google.golang.org/protobuf from 1.35.1 to 1.35.2 by @dependabot in https://github.com/prometheus/client_golang/pull/1697
• build(deps): bump golang.org/x/sys from 0.26.0 to 0.27.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1696
• build(deps): bump the github-actions group with 5 updates by @dependabot in https://github.com/prometheus/client_golang/pull/1695
• update links to openmetrics to reference the v1.0.0 release by @dashpole in https://github.com/prometheus/client_golang/pull/1699
• build(deps): bump google.golang.org/protobuf from 1.35.2 to 1.36.1 by @dependabot in https://github.com/prometheus/client_golang/pull/1706
• build(deps): bump golang.org/x/sys from 0.27.0 to 0.28.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1705
• build(deps): bump the github-actions group with 5 updates by @dependabot in https://github.com/prometheus/client_golang/pull/1707
• build(deps): bump github.com/prometheus/common from 0.60.1 to 0.61.0 by @dependabot in https://github.com/prometheus/client_golang/pull/1704
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1703
• Synchronize common files from prometheus/prometheus by @prombot in https://github.com/prometheus/client_golang/pull/1708
• Upgrade to prometheus/common 0.62.0 with breaking change by @bwplotka in https://github.com/prometheus/client_golang/pull/1712
• build(deps): bump golang.org/x/net from 0.26.0 to 0.33.0 in /tutorials/whatsup by @dependabot in https://github.com/prometheus/client_golang/pull/1713
• docs: Add RELEASE.md for the release process by @kakkoyun in https://github.com/prometheus/client_golang/pull/1690
• tutorials/whatsup: Updated deps by @bwplotka in https://github.com/prometheus/client_golang/pull/1716
• process collector: Fixed pedantic registry failures on darwin with cgo. by @bwplotka in https://github.com/prometheus/client_golang/pull/1715
• Revert "ci: daggerize test and lint pipelines (#1534)" by @bwplotka in https://github.com/prometheus/client_golang/pull/1717

New Contributors

• @parthlaw made their first contribution in https://github.com/prometheus/client_golang/pull/1606
• @mharbison72 made their first contribution in https://github.com/prometheus/client_golang/pull/1600
• @cuisongliu made their first contribution in https://github.com/prometheus/client_golang/pull/1513
• @ying-jeanne made their first contribution in https://github.com/prometheus/client_golang/pull/1626
• @Manask322 made their first contribution in https://github.com/prometheus/client_golang/pull/1657
• @jkroepke made their first contribution in https://github.com/prometheus/client_golang/pull/1665
• @imorph made their first contribution in https://github.com/prometheus/client_golang/pull/1672
• @mmorel-35 made their first contribution in https://github.com/prometheus/client_golang/pull/1676
• @shivanthzen made their first contribution in https://github.com/prometheus/client_golang/pull/1654
• @dashpole made their first contribution in https://github.com/prometheus/client_golang/pull/1699

Full Changelog: https://github.com/prometheus/client_golang/compare/v1.20.5...v1.21.0-rc.0