Bazel 4.0 and higher provides support for two release tracks: long term support (LTS) releases and rolling releases. This page covers versioning in Bazel, the types of releases, and the benefits of those releases for Bazel users and contributors.
Bazel uses a major.minor.patch semantic versioning scheme.
Using version 3.5.1 as an example, a new release of each type would result in these version numbers:
Bazel continually publishes rolling releases. Every major version is an LTS release. You can choose to follow either release cadence - updating from one LTS release to the next, or updating with each minor version release.
The image shows both rolling and LTS releases, and the expected support for each.
Each major version becomes a separate development branch on release. You can receive fixes to critical bugs on that branch without having to update to the Bazel release at head. Additional features on your major version branch become minor releases and the highest version on the branch is the supported version.
Each Bazel release is paired with a list of recommended rule versions that work together and there is strict backwards compatibility within each branch.
An LTS release is a major version (such as, 4.0) that is supported for 3 years after its release. A major version is released approximately every nine months.
Ongoing development on a release branch results in minor versions.
You can choose to pin your project to a major release and update to a newer version in your own time. This gives you time to preview upcoming changes and adapt to them in advance.
Rolling releases are periodically cut from Bazel's main branch. This release cadence involves a continuous delivery of preview releases of the next major Bazel version, which are in sync with Google’s internal Bazel releases.
Note that a new rolling release can contain breaking changes that are incompatible with previous releases.
