ddnet/scripts/android

Requirements for building for Android

• At least 10-15 GiB of free disk space.
• First follow the general instructions for setting up https://github.com/ddnet/ddnet for building on Linux. This guide has only been tested on Linux.
• Note: Use a stable version of Rust. Using the nightly version results in linking errors.
• Install the Android NDK (version 26) in the same location where Android Studio would unpack it (~/Android/Sdk/ndk/):

  mkdir ~/Android
  cd ~/Android
  mkdir Sdk
  cd Sdk
  mkdir ndk
  cd ndk
  wget https://dl.google.com/android/repository/android-ndk-r26d-linux.zip
  unzip android-ndk-r26d-linux.zip
  unlink android-ndk-r26d-linux.zip
  

• Install the Android SDK build tools (version 30.0.3) in the same location where Android Studio would unpack them (~/Android/Sdk/build-tools/):

  # Assuming you already created the Android/Sdk folders in the previous step
  cd ~/Android/Sdk
  mkdir build-tools
  cd build-tools
  wget https://dl.google.com/android/repository/build-tools_r30.0.3-linux.zip
  unzip build-tools_r30.0.3-linux.zip
  unlink build-tools_r30.0.3-linux.zip
  mv android-11 30.0.3
  

• Install the Android command-line tools and accept the licenses using the SDK manager, otherwise the Gradle build will fail if the licenses have not been accepted:

  # Assuming you already created the Android/Sdk folders in the previous step
  cd ~/Android/Sdk
  mkdir cmdline-tools
  cd cmdline-tools
  wget https://dl.google.com/android/repository/commandlinetools-linux-11076708_latest.zip
  unzip commandlinetools-linux-11076708_latest.zip
  unlink commandlinetools-linux-11076708_latest.zip
  mv cmdline-tools latest
  yes | latest/bin/sdkmanager --licenses
  

• Install cargo-ndk and add Android targets to rustup to build Rust with the Android NDK:

  cargo install cargo-ndk
  rustup target add armv7-linux-androideabi
  rustup target add i686-linux-android
  rustup target add aarch64-linux-android
  rustup target add x86_64-linux-android
  

• Install OpenJDK 21:

  sudo apt install openjdk-21-jdk
  

• Install 7zip for building ddnet-libs:

  sudo apt install p7zip-full
  

• Install ninja:

  sudo apt install ninja-build
  

• Install curl:

  sudo apt install curl
  

• (macOS only) Install coreutils so nproc is available:

  brew install coreutils
  

• Build the ddnet-libs for Android (see below). Follow all above steps first.

How to build the ddnet-libs for Android

• There is a script to automatically download and build all repositories, this requires an active internet connection and can take around 30 minutes:

  mkdir build-android-libs
  scripts/compile_libs/gen_libs.sh build-android-libs android
  

  Warning: Do not choose a directory inside the src folder!
• If you see several red error messages in the first few minutes, abort the compilation with repeated Ctrl+C presses. Examine the output and ensure that you installed the NDK to the correct location.
• After the script finished executing, it should have created a ddnet-libs directory in your selected output folder, which contains all libraries in the correct directory format and can be merged with the ddnet-libs folder in the source directory:

  cp -r build-android-libs/ddnet-libs/. ddnet-libs/
  

How to build the DDNet client for Android

• Open a terminal inside the ddnet project root directory and run the following:

  scripts/android/cmake_android.sh <x86/x86_64/arm/arm64/all> <Game name> <Package name> <Debug/Release> <Build folder>
  

  • The first parameter denotes the architecture. Use all to compile for all architectures. Note that all architectures will be compiled in parallel. For testing, only compile for one architecture initially to get readable output.
  • The second parameter denotes the APK name, which must be equal to the library name. If you want to rename the APK, do it after the build.
  • The third parameter denotes the package name of the APK.
  • The fourth parameter denotes the build type.
  • The fifth parameter denotes the build folder.
• Example to build only for x86_64 architecture in debug mode:

  scripts/android/cmake_android.sh x86_64 DDNet org.ddnet.client Debug build-android-debug
  

• To build a signed APK, generate a signing key and export environment variables before running the build script:

  keytool -genkey -v -keystore my-release-key.jks -keyalg RSA -keysize 2048 -validity 10000 -alias my-alias
  export TW_KEY_NAME=<key name>
  export TW_KEY_PW=<key password>
  export TW_KEY_ALIAS=<key alias>
  

• By default, the version code and name of the APK will be determined automatically based on the definitions in src/game/version.h. You can also specify the build version code and name manually before running the build script, e.g.:

  export TW_VERSION_CODE=20210819
  export TW_VERSION_NAME="1.0"
  

  The version code must increase for newer version in order for users to automatically update to them. The version name is the string that will be displayed to the user, e.g. 1.2.3-snapshot4.
• Example to build a signed APK in release mode for all architectures:

  keytool -genkey -v -keystore Teeworlds.jks -keyalg RSA -keysize 2048 -validity 10000 -alias Teeworlds-Key
  # It will prompt for the password, input for example "mypassword"
  export TW_KEY_NAME=Teeworlds.jks
  export TW_KEY_PW=mypassword
  export TW_KEY_ALIAS=Teeworlds-Key
  # Version code and name will be determined automatically
  scripts/android/cmake_android.sh all DDNet org.ddnet.client Release build-android-release
  

• Note that you should only generate a signing key once (and make backups). Users can only update apps automatically if the same package name and signing key have been used, else they must manually uninstall the old app.