Prometheus Go client library

This is the Go client library for Prometheus. It has two separate parts, one for instrumenting application code, and one for creating clients that talk to the Prometheus HTTP API.

This library requires Go1.19 or later.

The library mandates the use of Go1.19 or subsequent versions. While it has demonstrated functionality with versions as old as Go 1.17, our commitment remains to offer support and rectifications for only the most recent three major releases.

Important note about releases and stability

This repository generally follows Semantic Versioning. However, the API client in prometheus/client_golang/api/ is still considered experimental. Breaking changes of the API client will not trigger a new major release. The same is true for selected other new features explicitly marked as EXPERIMENTAL in CHANGELOG.md.

Features that require breaking changes in the stable parts of the repository are being batched up and tracked in the v2 milestone. The v2 development happens in a separate branch for the time being. v2 releases off that branch will happen once sufficient stability is reached. In view of the widespread use of this repository, v1 and v2 will coexist for a while to enable a convenient transition.

Instrumenting applications

The prometheus directory contains the instrumentation library. See the guide on the Prometheus website to learn more about instrumenting applications.

The examples directory contains simple examples of instrumented code.

Client for the Prometheus HTTP API

The api/prometheus directory contains the client for the Prometheus HTTP API. It allows you to write Go applications that query time series data from a Prometheus server. It is still in alpha stage.

Where is model, extraction, and text?

The model packages has been moved to prometheus/common/model.

The extraction and text packages are now contained in prometheus/common/expfmt.

Contributing and community

See the contributing guidelines and the Community section of the homepage.

client_golang community is also present on the CNCF Slack #prometheus-client_golang.

For Maintainers: Release Process

To cut a minor version:

1. Create a new branch release-<major>.<minor> on top of the main commit you want to cut the version from and push it.
2. Create a new branch on top of the release branch, e.g. <yourname>/cut-<major>.<minor>.<patch>,
3. Change the VERSION file.
4. Update CHANGELOG (only user-impacting changes to mention).
5. Create PR, and get it reviewed.
6. Once merged, create a release with the release-<major>.<minor> tag on GitHub with the <version> title.
7. Announce on the prometheus-announce mailing list, slack and Twitter.
8. Merge the release branch back to the main using the "merge without squashing" approach (!).

NOTE: In case of merge conflicts, you can checkout the release branch in a new branch, e.g. <yourname>/resolve-conflicts, fix the merge problems there, and then do a PR into main from the new branch. In that way, you still get all the commits in the release branch back into main, but leave the release branch alone.

To cut the patch version:

1. Create a branch on top of the release branch you want to use.
2. Cherry-pick the fixes from the main branch (or add new commits) to fix critical bugs for that patch release.
3. Follow steps 3-8 as above.