Building Node for Android

This repo uses a VM to build the node source code. To make use of the automatic features please install VirtualBox and Vagrant and then from the repo root simply execute vagrant up. You can then build node for Android by shelling into the VM with vagrant ssh and running the included script: ./build_node_for_android.sh

The binary is built for Android on a Debian system using the android ndk to cross compile the code. By inspecting the ./build_node_for_android.sh we can see one of the most important steps is to create a toolchain using the node provided script android-configure like so:

# Download the android ndk
wget "https://dl.google.com/android/repository/android-ndk-r15b-linux-x86_64.zip"
unzip android-ndk-r15b-linux-x86_64

# Get the node repo
git clone https://github.com/nodejs/node.git && cd node
git checkout boron || git checkout v6.11.2
make clean

# Setup the build environment for cross-compiling
export ANDROID_NDK_NAME=android-ndk-r15b
export ANDROID_NDK_HOME=~/$ANDROID_NDK_NAME/
export TOOLCHAIN=$PWD/android-toolchain
rm -rf $TOOLCHAIN
~/$ANDROID_NDK_NAME/build/tools/make-standalone-toolchain.sh --toolchain=arm-linux-androideabi-4.9 --arch=arm --install-dir=$TOOLCHAIN --platform=android-21
export PATH=$TOOLCHAIN/bin:$PATH
export AR=$TOOLCHAIN/bin/arm-linux-androideabi-ar
export CC=$TOOLCHAIN/bin/arm-linux-androideabi-gcc
export CXX=$TOOLCHAIN/bin/arm-linux-androideabi-g++
export LINK=$TOOLCHAIN/bin/arm-linux-androideabi-g++

# This script may prompt you to delete an existing directory.
# Say yes to delete it.
source android-configure $ANDROID_NDK_HOME

After this toolchain has been created then all the configure and build scripts from node will use it to build for Android from the Debian VM. The following configure call will setup the source to build node as a binary for Android. This is where you w

./configure \
	--dest-cpu=arm \
	--dest-os=android \
	--without-snapshot \
	--without-inspector \
	--without-intl \
	--without-dtrace \
	--without-etw \
	--without-perfctr \
	--openssl-no-asm \
  --shared # Leave this option off for an executable binary instead of .so

You can find more options in the official node configure script: https://github.com/nodejs/node/blob/master/configure

To compile node as a shared library you need to add --shared to the above configure script.

Then you can make the files with:

make -j4

scuttlebot on android

Setting target architecture for npm

Native npm modules require cross-compiling as well. We can instruct npm to target a specific architecture using npm config set arch=arm

You need ADB to push this to your device: http://developer.android.com/sdk/installing/

You need to push the tar file to the device and then unarchive it. This preserves symbolic links. My android only supports tar and not bz2 so I had to decompress the bz2 on my mac, then adb push the tar file, and untar the file from within adb shell.

Download scuttlebot.tar.bz2

bzip2 -d scuttlebot.tar.bz2
adb push scuttlebot.tar /data/local/tmp/scuttlebot.tar
adb shell

Then on the device:

export HOME=/data/local/tmp
cd $HOME
tar xf scuttlebot.tar
cd scuttlebot
./node ./sbot.js server