Setup the Android Build Environment

Doing a local build of the Glean SDK:

This document describes how to make local builds of the Android bindings in this repository. Most consumers of these bindings do not need to follow this process, but will instead use pre-built bindings.

Prepare your build environment

Typically, this process only needs to be run once, although periodically you may need to repeat some steps (e.g., Rust updates should be done periodically).

Setting up Android dependencies

With Android Studio

The easiest way to install all the dependencies (and automatically handle updates), is by using Android Studio. Once this is installed, start Android Studio and open the Glean project. If Android Studio asks you to upgrade the version of Gradle, decline.

The following dependencies can be installed in Android Studio through Tools > SDK Manager > SDK Tools:

You should be set to build Glean from within Android Studio now.

Manually

Set JAVA_HOME to be the location of Android Studio's JDK which can be found in Android Studio's "Project Structure" menu (you may need to escape spaces in the path).

Note down the location of your SDK. If installed through Android Studio you will find the Android SDK Location in Tools > SDK Manager.

Set the ANDROID_HOME environment variable to that path. Alternatively add the following line to the local.properties file in the root of the Glean checkout (create the file if it does not exist):

sdk.dir=/path/to/sdk

For the Android NDK (check here for the version requirements):

  1. Download NDK from https://developer.android.com/ndk/downloads.
  2. Extract it and put it somewhere ($HOME/.android-ndk-r25 is a reasonable choice, but it doesn't matter).
  3. Add the following line to the local.properties file in the root of the Glean checkout (create the file if it does not exist): 
    ndk.dir=/path/to/.android-ndk-r25

Setting up Rust

Rust can be installed using rustup, with the following commands:

curl https://sh.rustup.rs -sSf | sh
rustup update

Platform specific toolchains need to be installed for Rust. This can be done using the rustup target command. In order to enable building for real devices and Android emulators, the following targets need to be installed:

rustup target add aarch64-linux-android
rustup target add armv7-linux-androideabi
rustup target add i686-linux-android
rustup target add x86_64-linux-android

Building

Before building:

  • Ensure your repository is up-to-date.
  • Ensure Rust is up-to-date by running rustup update.

With Android Studio

After importing the Glean project into Android Studio it should be all set up and you can build the project using Build > Make Project

Manually

The builds are all performed by ./gradlew and the general syntax used is ./gradlew project:task

Build the whole project and run tests:

./gradlew build

You can see a list of projects by executing ./gradlew projects and a list of tasks by executing ./gradlew tasks.

FAQ

  • Q: Android Studio complains about Python not being found when building.
  • A: Make sure that the python binary is on your PATH. On Windows, in addition to that, it might be required to add its full path to the rust.pythonCommand entry in $project_root/local.properties.