Partner repacks

We create slightly-modified Firefox releases for some extra audiences

  • EME-free builds, which disable DRM plugins by default

  • Funnelcake builds, which are used for Mozilla experiments

  • partner builds, which customize Firefox for external partners

We use the phrase “partner repacks” to refer to all these builds because they use the same process of repacking regular Firefox releases with additional files. The specific differences depend on the type of build.

We produce partner repacks for some beta builds, and for release builds, as part of the release automation. We don’t produce any files to update these builds as they are handled automatically (see updates).

We also produce Partner attribution builds, which are Firefox Windows installers with a cohort identifier added.

Parameters & Scheduling

Partner repacks have a number of parameters which control how they work:

  • release_enable_emefree

  • release_enable_partner_repack

  • release_partner_config

  • release_partner_build_number

  • release_partners

We split the repacks into two ‘paths’, EME-free and everything else, to retain some flexibility over enabling/disabling them separately. This costs us some duplication of the kinds in the repacking stack. The two enable parameters are booleans to turn these two paths on/off. We set them in shipit’s is_partner_enabled() when starting a release. They’re both true for Firefox betas >= b8 and releases, but otherwise disabled.

release_partner_config is a dictionary of configuration data which drives the task generation logic. It’s usually looked up during the release promotion action task, using the Github GraphQL API in the get_partner_config_by_url() function, with the url defined in taskcluster/config.yml.

release_partner_build_number is an integer used to create unique upload paths in the firefox candidates directory, while release_partners is a list of partners that should be repacked (i.e. a subset of the whole config). Both are intended for use when respinning a few partners after the regular Firefox has shipped. More information on that can be found in the RelEng Docs.

Most of the machine time for generating partner repacks takes place in the promote phase of the automation, or promote_rc in the case of X.0 release candidates. The EME-free builds are copied into the Firefox releases directory in the push phase, along with the regular bits.


We need some configuration to know what to repack, and how to do that. The what is defined by default.xml manifests, as used with the repo tool for git. The default.xml for EME-free illustrates this:

<?xml version="1.0" ?>
  <remote fetch="" name="mozilla-partners"/>
  <remote fetch="" name="mozilla"/>

  <project name="repack-scripts" path="scripts" remote="mozilla-partners" revision="master"/>
  <project name="build-tools" path="scripts/tools" remote="mozilla" revision="master"/>
  <project name="mozilla-EME-free" path="partners/mozilla-EME-free" remote="mozilla-partners" revision="master"/>

The repack-scripts and build-tools repos are found in all manifests, and then there is a list of partner repositories which contain the how configuration. Some of these repos are not publicly visible.

A partner repository may contain multiple configurations inside the desktop directory. Each subdirectory must contain a repack.cfg and a distribution directory, the latter containing the customizations needed. Here’s EME-free’s repack.cfg:

locales="ach af an ar"  # truncated for display here

Note the list of locales and boolean toggles for enabling platforms.

All customizations will be placed in the distribution directory at the root of the Firefox install directory, or in the case of OS X in A distribution.ini file is the minimal requirement, here’s an example from EME-free:

# Partner Distribution Configuration File
# Author: Mozilla
# Date: 2015-03-27

about=Mozilla Firefox EME-free


Extensions and other customizations might also be included in repacks.

Repacking process

The stack of tasks to create partner repacks is broadly similar to localised nightlies and regular releases. The basic form is

  • partner repack - insert the customisations into the regular builds

  • signing - sign the internals which will become the installer (Mac only)

  • repackage - create the “installer” (Mac and Windows)

  • chunking dummy - a linux only bridge to …

  • repackage signing - sign the “installers” (mainly Windows)

  • beetmover - move the files to a partner-specific destination

  • beetmover checksums - possibly beetmove the checksums from previous step

Some key divergences are:

  • all intermediate artifacts are uploaded with a releng/partner prefix

  • we don’t insert any binaries on Windows so no need for internal signing

  • there’s no need to create any complete mar files at the repackage step

  • we only need beetmover checksums for EME-free builds

Partner repack

  • kinds: release-partner-repack release-eme-free-repack

  • platforms: Typically all (but depends on what’s enabled by partner configuration)

  • upstreams: build-signing l10n-signing

There is one task per platform in this step, calling out to scripts/ in mozharness to prepare an environment and then perform the repacks. The actual repacking is done by python/mozrelease/mozrelease/

It takes as input the build-signing and l10n-signing artifacts, which are all zip/tar.gz/tar.bz2 archives, simplifying the repack process by avoiding dmg and exe. Windows produces & setup.exe, Mac is target.tar.gz, Linux is the final product target.tar.bz2 (beetmover handles pretty naming as usual).


  • kinds: release-partner-repack-mac-signing release-partner-repack-mac-notarization

  • platforms: Mac

  • upstreams: release-partner-repack release-eme-free-repack

We chunk the single partner repack task out to a signing task with 5 artifacts each. For example, EME-free will become 19 tasks. We collect the target.tar.gz from the upstream, and return a signed target.tar.gz. We use a target.dmg artifact for nightlies/regular releases, but this is converted to target.tar.gz by the signing scriptworker before sending it to the signing server, so partners are equivalent. The mac-signing task signs the binary, and then mac-notarization submits it to Apple and staples the ticket to it.


  • kinds: release-partner-repack-repackage release-eme-free-repack-repackage

  • platforms: Mac & Windows

  • upstreams:

    • Mac: release-partner-signing release-eme-free-signing

    • Windows: release-partner-repack release-eme-free-repack

Mac has a repackage job for each of the signing tasks. Windows repackages are chunked here to the same granularity as mac. Takes & setup.exe to produce target.exe on Windows, and target.tar.gz to produce target.dmg on Mac. There’s no need to produce any complete.mar files here like regular release bits do because we can reuse those.

Chunking dummy

  • kinds: release-partner-repack-chunking-dummy

  • platforms: Linux

  • upstreams: release-partner-repack

We’re need Linux chunked at the next step so this dummy takes care of that for the relatively simple path Linux follows. One task per sub config+locale combination, the same as Windows and Mac. This doesn’t need to exist for EME-free because we don’t need to create Linux builds there.

Repackage Signing

  • kinds: release-partner-repack-repackage-signing release-eme-free-repack-repackage-signing

  • platforms: All

  • upstreams:

    • Mac & Windows: release-partner-repackage release-eme-free-repackage

    • Linux: release-partner-repack-chunking-dummy

This step GPG signs all platforms, and authenticode signs the Windows installer.


  • kinds: release-partner-repack-beetmover release-eme-free-repack-beetmover

  • platforms: All

  • upstreams: release-partner-repack-repackage-signing release-eme-free-repack-repackage-signing

Moves and renames the artifacts to their public location in the candidates directory. Each task will have the project:releng:beetmover:action:push-to-partner and project:releng:beetmover:bucket:release scopes. There’s a separate partner code path in beetmoverscript.

Beetmover checksums

  • kinds: release-eme-free-repack-beetmover-checksums

  • platforms: Mac & Windows

  • upstreams: release-eme-free-repack-repackage-beetmover

The EME-free builds should be present in our SHA256SUMS file and friends (e.g.) so we beetmove the target.checksums from the beetmover tasks into the candidates directory. They get picked up by the release-generate-checksums kind.


It’s very rare to need to update a partner repack differently from the original release build but we retain that capability. A partner build with distribution name foo, based on a release Firefox build, will query for an update on the release-cck-foo channel. If the update server Balrog finds no rule for that channel it will fallback to the release channel. The update files for the regular releases do not modify the distribution/ directory, so the customizations are not modified.

Bug 1430254 is an example of an exception to this logic.