Creating Toolchain Archives

There are various scripts in the repository for producing archives of the build tools (e.g. compilers and linkers) required to build.


See the build/build-clang directory. Read build/build-clang/README for more.


The build/ script is used to build and manage Windows toolchain archives containing Visual Studio executables, SDKs, etc.

The way Firefox build automation works is an archive containing the toolchain is produced and uploaded to an internal Mozilla server. The build automation will download, verify, and extract this archive before building. The archive is self-contained so machines don’t need to install Visual Studio, SDKs, or various other dependencies. Unfortunately, Microsoft’s terms don’t allow Mozilla to distribute this archive publicly. However, the same tool can be used to create your own copy.

Configuring Your System

It is highly recommended to perform this process on a fresh installation of Windows 7 or 10 (such as in a VM). Installing all updates through Windows Update is not only acceptable - it is encouraged. Although it shouldn’t matter.

Next, install Visual Studio 2015 Community. The download link can be found at Be sure to follow these install instructions:

  1. Choose a Custom installation and click Next
  2. Select Programming Languages -> Visual C++ (make sure all sub items are selected)
  3. Under Windows and Web Development uncheck everything except Universal Windows App Development Tools and the items under it (should be Tools (1.3.1)... and the Windows 10 SDK).

Once Visual Studio 2015 Community has been installed, from a checkout of mozilla-central, run something like the following to produce a ZIP archive:

$ ./mach python build/ create-zip vs2017_15.4.2

The produced archive will be the argument to create-zip + .zip.

Firefox for Android with Gradle

To build Firefox for Android with Gradle in automation, archives containing both the Gradle executable and a Maven repository comprising the exact build dependencies are produced and uploaded to an internal Mozilla server. The build automation will download, verify, and extract these archive before building. These archives provide a self-contained Gradle and Maven repository so that machines don’t need to fetch additional Maven dependencies at build time. (Gradle and the downloaded Maven dependencies can be both redistributed publicly.)

Archiving the Gradle executable is straight-forward, but archiving a local Maven repository is not. Therefore a special Task Cluster Docker image and toolchain job exist for producing the required archives. The Docker image definition is rooted in taskcluster/docker/android-build. The Task Cluster toolchain job is named android-gradle-dependencies. The job runs in a container based on the custom Docker image and spawns a Sonatype Nexus proxying Maven repository process in the background. The job builds Firefox for Android using Gradle and the in-tree Gradle configuration rooted at build.gradle. The spawned proxying Maven repository downloads external dependencies and collects them. After the Gradle build completes, the job archives the Gradle version used to build, and the downloaded Maven repository, and exposes them as Task Cluster artifacts.

To update the version of Gradle in the archive produced, update gradle/wrapper/ Be sure to also update the SHA256 checksum to prevent poisoning the build machines!

To update the versions of Gradle dependencies used, update dependencies sections in the in-tree Gradle configuration rooted at build.gradle. Once you are confident your changes build locally, push a fresh build to try. The android-gradle-dependencies toolchain should run automatically, fetching your new dependencies and wiring them into the appropriate try build jobs.

To update the version of Sonatype Nexus, update NEXUS_VERSION in the android-build Docker image.

To modify the Sonatype Nexus configuration, typically to proxy a new remote Maven repository, modify taskcluster/scripts/misc/android-gradle-dependencies/nexus.xml.

There is also a toolchain job that fetches the Android SDK and related packages. To update the versions of packaged fetched, modify python/mozboot/mozboot/android-packages.txt and update the various in-tree versions accordingly.