Packaging app for Android
Introduction
Flet CLI provides flet build apk and flet build aab commands that allow packaging Flet app into Android APK and Android App Bundle (AAB) respectively.
Prerequisites
Binary Python packages
Binary Python packages (vs "pure" Python packages written in Python only) are packages that partially written in C, Rust or other languages producing native code. Example packages are numpy, cryptography, or pydantic.
Flet provides an alternative index https://pypi.flet.dev to host Python binary wheels (.whl files downloaded by pip) for iOS and Android platforms.
The following packages are currently available for Android:
| Name | Version |
|---|---|
| aiohttp | 3.9.5 |
| argon2-cffi-bindings | 21.2.0 |
| bcrypt | 4.2.0 |
| bitarray | 2.9.2 |
| blis | 1.0.0 |
| Brotli | 1.1.0 |
| cffi | 1.17.1 |
| contourpy | 1.3.0 |
| cryptography | 43.0.1 |
| google-crc32 | 1.6.0 |
| grpcio | 1.67.1 |
| kiwisolver | 1.4.7 |
| lru-dict | 1.3.0 |
| lxml | 5.3.0 |
| MarkupSafe | 2.1.5 |
| matplotlib | 3.9.2 |
| numpy | 2.1.1 |
| numpy | 1.26.4 |
| opencv-python | 4.10.0.84 |
| pandas | 2.2.2 |
| pillow | 10.4.0 |
| protobuf | 5.28.3 |
| pydantic-core | 2.23.3 |
| time-machine | 2.16.0 |
| websockets | 13.0.1 |
| yarl | 1.11.1 |
New packages can be built with creating a recipe in Mobile Forge project. For now, Flet team is authoring those recipes for you, but when the process is polished and fully-automated you'll be able to send a PR and test the compiled package right away.
If you don't yet see a package at https://pypi.flet.dev you can request it in Flet discussions - Packages. Please do not request pure Python packages. Go to package's "Download files" section at https://pypi.org and make sure it contains binary platform-specific wheels.
Android SDK
To build the app for the Android platform, the flet build command requires the Android SDK to be installed on your machine.
The official way to install the Android SDK and Java is by installing Android Studio.
On macOS Android SDK will be located at $HOME/Library/Android/sdk.
flet build apk
Build an Android APK file from your app.
This command builds release version. 'release' builds don't support debugging and are suitable for deploying to app stores. If you are deploying the app to the Play Store, it's recommended to use Android App Bundles (AAB) or split the APK to reduce the APK size.
- https://developer.android.com/guide/app-bundle
- https://developer.android.com/studio/build/configure-apk-splits#configure-abi-split
Building platform-specific APKs
By default, Flet builds "fat" APK which includes binaries for both arm64-v8a and armeabi-v7a architectures.
You can configure Flet to split fat APK into smaller APKs for each platformby using --split-per-abi option or by setting split_per_abi in pyproject.toml:
[tool.flet.android]
split_per_abi = true
Installing APK to a device
The easiest way to install APK to your device is to use adb (Android Debug Bridge) tool.
adb is a part of Android SDK. For example, on macOS, if Android SDK was installed with Android Studio
the location of adb tool will be at ~/Library/Android/sdk/platform-tools/adb.
Check this article for more information about installing and using adb tool on various platforms.
To install APK to a device run the following command:
adb install <path-to-your.apk>
If more than one device is connected to your computer (say, emulator and a physical phone) you can
use -s option to specify which device you want to install .apk on:
adb -s <device> install <path-to-your.apk>
where <device> can be found with adb devices command.
flet build aab
Build an Android App Bundle (AAB) file from your app.
This command builds release version. 'release' builds don't support debugging and are suitable for deploying to app stores. App bundle is the recommended way to publish to the Play Store as it improves your app size.
Signing Android bundle
TBD
[tool.flet.android.signing]
# store and key passwords can be passed with `--android-signing-key-store-password`
# and `--android-signing-key-password` options or
# FLET_ANDROID_SIGNING_KEY_STORE_PASSWORD
# and FLET_ANDROID_SIGNING_KEY_PASSWORD environment variables.
key_store = "path/to/store.jks" # --android-signing-key-store
key_alias = "upload"
Splash screen
By default, generated Android app will be showing a splash screen with an image from assets directory (see below) or Flet logo. You can disable splash screen for Android app with --no-android-splash option.
Configuring splash in pyproject.toml:
[tool.flet.splash]
android = false
Permissions
Configuring Android permissions and features to be written into AndroidManifest.xml:
flet build --android-permissions permission=True|False ... --android-features feature_name=True|False
For example:
flet build \
--android-permissions android.permission.READ_EXTERNAL_STORAGE=True \
android.permission.WRITE_EXTERNAL_STORAGE=True \
--android-features android.hardware.location.network=False
Default Android permissions:
android.permission.INTERNET
Default permissions can be disabled with --android-permissions option and False value, for example:
flet build --android-permissions android.permission.INTERNET=False
Default Android features:
android.software.leanback=False(Falsemeans it's written in manifest asandroid:required="false")android.hardware.touchscreen=False
Configuring permissions and features in pyproject.toml (notice quotes " around key names):
[tool.flet.android.permission] # --android-permissions
"android.permission.CAMERA" = true
"android.permission.CAMERA" = true
[tool.flet.android.feature] # --android-features
"android.hardware.camera" = false
Meta-data
Configuring Android app meta-data to be written into AndroidManifest.xml:
flet build --android-meta-data name_1=value_1 name_2=value_2 ...
Default Android meta-data:
io.flutter.embedding.android.EnableImpeller=false
Configuring meta-data in pyproject.toml (notice quotes " around key names):
[tool.flet.android.meta_data]
"com.google.android.gms.ads.APPLICATION_ID" = "ca-app-pub-xxxxxxxxxxxxxxxx~yyyyyyyyyy"
Deep linking
You can configure deep-linking settings for Android app with the following flet build options:
--deep-linking-scheme- deep linking URL scheme to configure for Android builds, i.g. "https" or "myapp".--deep-linking-host- deep linking URL host.
The same can be configured in pyproject.toml:
[tool.flet.android.deep_linking]
scheme = "https"
host = "mydomain.com"
See Deep linking section in Flutter docs for more information and complete setup guide.
Troubleshooting Android
To run interactive commands inside simulator or device:
adb shell
To overcome "permissions denied" error while trying to browse file system in interactive Android shell:
su
To download a file from a device to your local computer:
adb pull <device-path> <local-path>