Mozilla uses Microsoft GitHub as the official home for Firefox source code

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Mozilla has moved the central repository for the development of the Firefox browser to GitHub. This completes the migration of version management from Mercurial to Git.

The official announcement can be found in the Google Docs document on the Git migration status. According to this, Mozilla completed the migration on April 30.

Consistent development with Git

Byron “Glob” Jones, Senior Engineer Manager at Mozilla, announced the move in November 2023. Until then, development took place on two tracks with the version management systems Mercurial and Git. Both Mercurial and Git are open-source software. GitHub, the platform for managing Git projects acquired by Microsoft in 2018, is not open source, but many open-source projects are developed here.

The move to unified development with Git is intended to reduce the overhead of using two version management systems. According to Jones, it placed a considerable burden on teams, some of which were already overloaded.

Limited use

However, unlike many other projects, the further development of Firefox does not take place directly on GitHub, but the platform primarily serves as a central location for the repository. The migration status document from April lists the main changes resulting from the migration. Those who have been working on Firefox with Git so far do not need to change their workflows.

There will be no pull requests via GitHub for the foreseeable future, and the team will not collect issues on the platform. Instead, Mozilla will continue to rely on the tools Bugzilla, Lando and Phabricator for reviews, issues, and changes. The fact that Mozilla is sticking with the latter is somewhat surprising: Phacility, the company behind Phabricator, discontinued work on the project in 2021. Phorge is a fork of the project.

In good company for the move

Before Firefox, the programming languages Java and Python switched their further development from Mecurial to Git. It took a little longer for Java: the first proposals to move away from the Mercurial version management system were made in 2018, the following year the decision was made in favor of Git and another two years passed before the final move to GitHub.

The LLVM compiler infrastructure also moved to GitHub in 2019. Previously, those responsible used Apache Subversion (SVN) for version management.

Mike Hommey, who – appears on GitHub – as glandium, has written a detailed, unofficial guide to the Git migration. In another blog post, he gives detailed reasons for the migration from Mercurial to Git and the choice of GitHub as a platform.

(rme)