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Android 版 Firefox の簡単なビルド

このページでは Fennec という名で知られている Android 版 Firefox に関する、最新のビルドに必要な基礎ステップをカバーしています。ようこそ!そしてあなたに会えてとても嬉しいです。

もしこのドキュメントについてのトラブルや解決できない壁にぶち当たったら、あなたの問題や、あなたに続く貢献者の問題を解決するために Nick Alexander(に直接メールをしてください。

これに加え、さらなる情報を得る場合は、 Firefox for Android wiki とFirefox の一般的なビルドドキュメント を参考にしてください。


Mac OS X や多くの Linux を含む、UNIX ライクなシステム上だと、すぐに Android 版 Firefox をビルドすることができます。多くのコア開発者は Mac OS X 上で開発し、Linux は少数派です。

Android 版 Firefox を Microsoft Windows 上でビルドすることは、まだサポートされていません。この作業は優先順位が低いだけで、してはいけない理由は全くありません。(過去、Google は Windows 向けの Android ツールチェインの一部をリリースしていなかったので不可能でした) 。もし WIndows 上でのビルドに興味がある場合や貢献できる場合は、 bug 1169873 に CC として追加してください。


  • 古いマシンで Firefox をビルドすることはできますが、遅いマシンでのコンパイルにとても時間がかかります。最低でも 8GB の RAM を推奨します。
  • もし古いマシンを持っていれば、artifact モード をお勧めします。
  • また高速インターネットを強く推奨します。環境構築とソースコードレポジトリはとても巨大です。Artifact モード でも通常のダウンロードするバイナリは多いです(50MB)。
  • You must have a 64-bit operating system. As of early 2015 it is no longer possible to build Firefox on most 32-bit machines.
  • If you're going to install Firefox for Android on a physical Android device, you'll need one running Android Ice Cream Sandwich (API 15) or later.

Bootstrap dependencies

Run either of the following in a terminal.  You'll need Python version 2.7 or later and curl or wget.  If you have curl installed (note that Mac OS X ships curl by default):

curl -O && python

Or, if you have wget installed instead:

wget -q && python

Choose Firefox for Android when prompted.  The bootstrapping script will install system packages, the Android SDK (and NDK, if required), and the currently required versions of the Android platform and extras.

The bootstrap script will print out configuration options for you when it finishes more on this below.  For now, copy this configuration text and continue on.  You can re-run the bootstrap script to print this information again later.

Once you have all the dependencies installed, you need to clone the Firefox repository.

Get the source

Get the latest source code from Mozilla's Mercurial code repository. This may take a while; it's a lot of code!  We recommend that you add the progress extension to your Mercurial configuration.  This will provide feedback during the lengthy clone process.  See the documentation explaining how to enable the Mercurial progress extension.

hg clone

If you are using a slow or unreliable internet connection, hg clone might fail because it gets interrupted. In that case, you are strongly encouraged to download a Mercurial bundle file instead of waiting for hg clone.

Choose what parts of Firefox for Android you want to modify

Firefox for Android is built in two layers.  The Firefox for Android “front-end” — which includes the home panels, UI for settings, menus, etc., Firefox Sync, and most data storage — is implemented using Java, the Android Platform SDK, JavaScript, HTML, and CSS.  Firefox for Android is built on top of the Gecko platform back-end. Gecko is Mozilla's web rendering engine, similar to Edge, Blink, and WebKit, and is responsible for rendering web content, running JavaScript code, and providing web APIs to pages. Gecko is implemented using C++ and JavaScript.

Here is a table summarizing the pros and cons of working on the different parts.

Configuration Restrictions Implementation languages Build speed Integrated development environment
front-end Can only modify main UI, not web platform Java, JavaScript Fast builds Android Studio or IDEA IntelliJ
back-end None: can modify everything C++, JavaScript Slow builds None: use your text editor

Do you want to modify just Firefox for Android, or do you want to modify the Gecko platform?

If you don't know what you want, start with just the Firefox for Android front-end: your build times will be much shorter if you don't build the Gecko back-end as well.

But don't worry! You can always add the back-end configuration later, and it's easy to switch between the configurations.

Prepare a Firefox for Android mozconfig

The build scripts will read from the mozconfig file in your source directory (where you cloned the mozilla-central source repository into) to determine what kind of build to produce, although you can configure this if you need to.  You must use $HOME instead of ~ in your mozconfig because ~ does not get expanded.

By default, the build system creates a build of Firefox for Android roughly equivalent to the official Firefox for Android Nightly builds. If that's not exactly what you want, there are many build configuration options to choose from, although it's strongly recommended that you only use options that you fully understand.

I want to work on the front-end

Firefox for Android supports a fast build mode called artifact mode.  (Some mobile team managers call it manager mode since it's particularly helpful if you only write code infrequently.)  Artifact mode downloads pre-built C++ components rather than building them locally, trading bandwidth for time.

To use artifact mode, paste the following into your mozconfig file:

# Build Firefox for Android:
ac_add_options --enable-application=mobile/android
ac_add_options --target=arm-linux-androideabi

# With the following Android SDK:
ac_add_options --with-android-sdk="/absolute/path/to/android-sdk"

# Enable artifact building:
ac_add_options --enable-artifact-builds

# Write build artifacts to:
mk_add_options MOZ_OBJDIR=./objdir-frontend

Artifact mode needs certain Mercurial extensions to function.  At this time, it's not possible to use artifact mode with git.  First run mach mercurial-setup to prepare the needed mercurial extensions:

./mach mercurial-setup

Next you will have to add a line like the following to the Mercurial config file .hg/hgrc in your source directory (you may need to adjust the path depending on your setup, look at your ~/.hgrc for the paths that mercurial-setup used for the extensions that it configured):

mozext = ~/.mozbuild/version-control-tools/hgext/mozext

Next, download a local copy of the Mozilla pushlog with:

hg pushlogsync

Mercurial should show a long (and slow) progress bar. From now on, each time you hg pull code changes from Mozilla, you’ll also automatically update your local copy of the pushlog.

You should be ready to build with artifact mode!

I want to work on the back-end

Paste the following into your mozconfig file:

# Build Firefox for Android:
ac_add_options --enable-application=mobile/android
ac_add_options --target=arm-linux-androideabi

# With the following Android SDK and NDK:
ac_add_options --with-android-sdk="/absolute/path/to/android-sdk"
ac_add_options --with-android-ndk="/absolute/path/to/android-ndk-r10e" 

# Write build artifacts to:
mk_add_options MOZ_OBJDIR=./objdir-droid

If you're planning on hacking the C/C++ code, you probably want to create a debug build instead of a release build.  Add the following lines to your mozconfig:

ac_add_options --enable-debug
ac_add_options --disable-optimize

Configuration options

I want to build an x86 version of Firefox for Android

Note: Only API 15+ are supported on x86 architecture.

Version 23 and later Android x86 emulators with hardware acceleration are fast enough for local development.  They're an attractive alternative if you have recent hardware and an old Android device (or no Android device).  Both artifact mode and regular mode support building APKs for x86 architectures.  Just replace the line ac_add_options --target=arm-linux-androideabi with:

ac_add_options --target=i386-linux-android

(You probably want to change the MOZ_OBJDIR directory, too.)  Now when you build, you should produce an x86 version of Firefox for Android!

For more configuration options, see the general Firefox documentation on configuring build options.

Deploy Firefox to an Android device

Quick start

The bare minimum: run these commands to build, package, install, and run a fresh Firefox for Android on your Andorid device.

I am working on the front-end using artifact mode

./mach build
./mach artifact install
./mach package
./mach install
./mach run

I am working on the back-end (and not using artifact mode)

./mach build
./mach package
./mach install
./mach run

Each step is discussed in more detail below.

bug 1216817 tracks running the required mach artifact command automatically.


Before you start building, connect your Android device and enable USB debugging. Now cd into the mozilla-central subdirectory (created by the hg clone command).

To build Firefox for Android (compile and link all C/C++, Java, and JavaScript source code), run:

./mach build

Building can take a significant amount of time, depending on your hardware, OS, and chosen build options. Linux builds on a fast box may take under 15 minutes, but builds on a slow machine may take several hours. If you're using artifact mode, builds should take less than five minutes. See tips for making builds faster.

The first time you run mach build, mach will ask you if you'd like to create a .mozbuild directory in your home folder and wait 20 seconds for your answer. This a good default location and you should allow it to create the directory.


To build after making changes, run

./mach build

again. This will only rebuild what is necessary for these changes. It is also possible to use

./mach build mobile/android

to build only changed Firefox for Android front-end code. If you are using artifact mode, this should always work. If you are building the Gecko back-end, this may yield incorrect results, so it is not recommended.


Running an Android application on a device is a little more involved than running a Desktop Firefox binary.  First, we need to package everything into an Android package.  To produce an APK, run

If you're using artifact mode, run

./mach package

The produced APK file can be found in your $OBJDIR/dist folder, and will be called something like

Install and run

To install the Android package to your device and launch it, run

./mach install
./mach run

The name of the App that appears on your Android device will be "Fennec $USER", where $USER is the username under which you built the code.

Note that you will need a device running Android Ice Cream Sandwich (API 15) or later.

Developing Firefox for Android in Android Studio or IDEA IntelliJ

The Firefox for Android front-end team develop the product in IDEA IntelliJ (both Community and Ultimate Editions) and Android Studio.  There is a Gradle build configuration, parallel to the mach build configuration.  Eventually, we intend to use Gradle in the mach build configuration.

The Gradle configuration is now "in the source directory".  To verify that everything is working, ensure that you've built and packaged successfully, and then run:

./gradlew clean app:assembleDebug

Next, simply import the top source directory (mozilla-central, as produced by hg clone) into your IDE.  This depends on the IDE; in Android Studio, it looks like:

Choose "Import from Gradle".

Choose the top source directory.

The IDE shows several projects after importing the top source directory.


In IDEA IntelliJ, it looks like:

  • File > Import Project... and select /path/to/mozilla-central.
  • Select Import project from external model > Gradle > Next.
  • Select Use default gradle wrapper > Finish.

You should have a shiny new Gradle-based project in your IDE! Try it out by choosing Build > Rebuild project.

Setting the Run/Debug Configuration and Build Variant

The Gradle build configuration may contain more than one Gradle module, which can define many Run/Debug Configurations.  You want the "app" Run Configuration:

Choose "app" from the Run Configurations list.

See the IntelliJ documentation for more.

The configuration also defines multiple Product Flavors, which contribute to Build Variants.  You want:

Testing device or emulator Android API Product Flavor Build Variant
>=21 local localDebug
<21 localOld localOldDebug

Choose "local" if you have an Android 21+ device; choose "localOld" if you have an Android <21 device.

See the Google build documentation for more.

Things that are supported in the IDE

  • Running, debugging, and profiling Firefox for Android in the IDE.  The app project defines the Android Application.
  • Editing Java source code under mobile/android.  Modifications to any of the Java code should prompt a fresh build and install.
  • Editing Android resources under mobile/android, including in mobile/android/base/resources.  In many cases the Android Layout Editor is fully functional.
  • Modifying the Android string definitions in mobile/android/base/ and mobile/android/base/locales/en-US/*.dtd.  Modifications should be picked up at the next build; they may not be noticed automatically.  (This is because the Android strings.xml file is generated, and the generation only happens in response to a build.)
  • Editing "omnijar" JavaScript source code under mobile/android, including in mobile/android/content, mobile/android/components, and mobile/android/modules, and under toolkit/.  Modifications to JavaScript code should be picked up at the next build.  Such modifications should rebuild the omnijar and prompt a fresh build and install.
  • Editing "omnijar" chrome XHTML, CSS, and JS resources under mobile/android, including in mobile/android/content, and under toolkit/.

Things that are not supported in the IDE

  • Modifying build system configuration and definitions and modifying mobile/android/base/ or the sub-manifests.  See bug 1221344 for an example of what can go wrong here.
  • Modifying generate Java code such as mobile/android/base/java/org/mozilla/gecko/
  • Modifying C++ source code anywhere in the tree.
  • Modifying "omnijar" JavaScript source code outside of mobile/android.  (If you modify JavaScript outside of mobile/android, say under dom/, the changes will be recognized the next time "omnijar" files inside mobile/android are edited.)
  • Running Robocop tests.  (Use mach robocop to run these tests locally.)
  • Running mochitest-chrome tests.  (Use mach test to run these tests locally.)


  • First, check if the Gradle configuration is working.  Make sure

    ./gradlew clean app:assembleDebug

    completes successfully.

  • Second, check that you're building the correct Gradle module and the correct build variant. If you see a runtime error like

    A/GeckoLoader: Couldn't load mozglue. Trying native library dir.
    A/GeckoLoader: Library doesn't exist when it should.
    then you are probably running the "automation" Build Variant.  See the documentation on Build Variants and the discussion in bug 1246055.
  • Third, ensure that you can install the APK to your device.  Make sure

    ./gradlew clean app:install{Local,LocalOld}Debug

    completes successfully, where you choose "Local" or "LocalOld" depending on your target device.  See the documentation on Build Variants.

  • It's possible to confuse the IDE about the state of the source directory.  To recover, try the following:
    • Select the root project and refresh everything in the IDE.
    • Open the root build.gradle file. If the IDE warns that the Gradle configuration has changed, accept the offer to Sync now.
    • Refresh the Gradle model manually: select View > Tool Windows > Gradle and click the blue Sync button in the top left.  In Android Studio, there's an icon to do this in the main toolbar -- it's labeled Sync Project with Gradle Files.
    • Clear the IDE cache manually:  select File > Invalidate caches and then restart the IDE.  (This should never be necessary.)

Required Android SDK and NDK versions

The Fennec build system requires the following versions:

If your build fails because you're missing one of the Android or Google requirements, your first step should be to run mach bootstrap. If you don't want to run the bootstrapper, you can manually install by running the Android SDK manager: try mach android, or $ANDROID_SDK/tools/android.

Requirement Version required
Android SDK Platform Android 6.0 (API 23)
SDK Build Tools 23.0.1
SDK Platform Tools 23.0.1
Android SDK Tools 23.0.1
Android Support Repository 21 (or later)
Google Repository 22 (or later)
Android NDK r10e

bug 1207680 tracks listing these version requirements in one place in the source code.


 このページの貢献者: teoli, mantaroh
 最終更新者: teoli,