Project: /_project.yaml Book: /_book.yaml

Updating Bazel

This page covers how to automatically update your Bazel version using Bazelisk.

Bazel has a backward compatibility policy (see guidance for rolling out incompatible changes if you are the author of one). That page summarizes best practices on how to test and migrate your project with upcoming incompatible changes and how to provide feedback to the incompatible change authors.

Managing Bazel versions with Bazelisk {:#manage-with-bazelisk}

Bazelisk{: .external} helps you manage Bazel versions.

Bazelisk can:

• Auto-update Bazel to the latest LTS or rolling release.
• Build the project with a Bazel version specified in the .bazelversion file. Check in that file into your version control to ensure reproducibility of your builds.
• Help migrate your project for incompatible changes (see above)
• Easily try release candidates

Recommended migration process {:#migration-process}

Within minor updates to any LTS release, any project can be prepared for the next release without breaking compatibility with the current release. However, there may be backward-incompatible changes between major LTS versions.

Follow this process to migrate from one major version to another:

1. Read the release notes to get advice on how to migrate to the next version.
2. Major incompatible changes should have an associated --incompatible_* flag and a corresponding GitHub issue:
   • Migration guidance is available in the associated GitHub issue.
   • Tooling is available for some of incompatible changes migration. For example, buildifier{: .external}.
   • Report migration problems by commenting on the associated GitHub issue.

After migration, you can continue to build your projects without worrying about backward-compatibility until the next major release.