Python 3 Android

This is an experimental set of build scripts that will cross-compile the latest Python 3 git master for an Android device.

Prerequisites

Building requires:

Linux. This project might work on other Unix-like systems but no guarantee.
Android NDK r21 installed and environment variable $ANDROID_NDK points to its root directory. Older NDK may not work and NDK <= r18 is known to break.
git and python3.9 in $PATH. It's recommended to use the latest git-master to build python3.9. Here are some ways to install the python3.9:

For Arch Linux users, install python-git package from AUR
For other users, install 3.9 from pyenv

Running requires:

Android 5.0 (Lollipop, API 21) or above
arm, arm64, x86 or x86-64

Build

Run ./clean.sh for good measure.
For every API Level/architecture combination you wish to build for:
- ARCH=arm ANDROID_API=21 ./build.sh to build everything!

Build using Docker

docker build -t python3-android-base docker
docker run --rm -it --user $(id -u):$(id -g) -v $(pwd):/python3-android --env ARCH=arm --env ANDROID_API=21 python3-android-base

Installation

Make sure adb shell works fine
Copy all files in build to a folder on the device (e.g., /data/local/tmp/python3). Note that on most devices /sdcard is not on a POSIX-compliant filesystem, so the python binary will not run from there.
In adb shell:

cd /data/local/tmp/build
. ./env.sh
python3

And have fun!

SSL/TLS

SSL certificates have old and new naming schemes. Android uses the old scheme yet the latest OpenSSL uses the new one. If you got CERTIFICATE_VERIFY_FAILED when using SSL/TLS in Python, you need to collect system certificates:

cd /data/local/tmp/build
mkdir -p etc/ssl
cat /system/etc/security/cacerts/* > etc/ssl/cert.pem

Path for certificates may vary with device vendor and/or Android version. Note that this approach only collects system certificates. If you need to collect user-installed certificates, most likely root access on your Android device is needed.

Check SSL/TLS functionality with:

import urllib.request
print(urllib.request.urlopen('https://httpbin.org/ip').read().decode('ascii'))

Known Issues

No big issues! yay