Android release builds

Two builds

The app has two flavors with the same application ID. They differ in how a plan is paid for, and in whether Google’s closed billing library is in the APK:

• foss, the default: no Google Play billing. For F-Droid and direct downloads, add --dart-define=BALNANA_EXTERNAL_PAYMENTS=true to offer Ko-fi and PayPal.
• play: sells Google Play subscriptions. It refuses to build with BALNANA_EXTERNAL_PAYMENTS, since Google Play doesn’t let an app send people elsewhere to pay.

flutter build appbundle --flavor play
flutter build apk --release --flavor foss --dart-define=BALNANA_EXTERNAL_PAYMENTS=true

APKs land in build/app/outputs/flutter-apk/app-<flavor>-release.apk.

Create an upload key

Release builds are signed with your own upload key. Create one once and keep it, and its passwords, safe: every later update must be signed with the same key.

keytool -genkeypair -v -keystore ~/balnana-upload.jks \
  -keyalg RSA -keysize 2048 -validity 10000 -alias upload

Then create app/android/key.properties (git ignores it):

storeFile=/home/you/balnana-upload.jks
storePassword=...
keyAlias=upload
keyPassword=...

storeFile may also be relative to app/android/. flutter build apk --release (or appbundle --flavor play) now signs with that key. Without key.properties, release builds stop with an error.

To try a release APK anyway, sign it with the debug key:

flutter build apk --release --android-project-arg=allowDebugSigning=true

Caution

An APK signed with the debug key cannot update an installed, properly signed app, nor the reverse.

Publishing checklist

App stores such as Google Play ask for a few things the code cannot supply:

• A default server. Build with --dart-define=BALNANA_SERVER_URL=https://... so people do not have to type an address on first launch.
• A privacy policy URL, public and reachable without signing in: set BALNANA_PRIVACY_URL to your policy, or give the store <server>/privacy, the built-in notice.
• An account deletion URL (accounts mode): <server>/delete-account.
• The release key for the app bundle: flutter build appbundle --flavor play refuses to build without it. With Play App Signing, add Play’s app signing certificate fingerprint to BALNANA_ANDROID_CERT_SHA256 as well, so app links keep working.
• The data safety form. The server stores names, email addresses, the groups’ expenses and receipt photos, the payment details members add, and (with push notifications) the push service address each phone gives it. Expenses may also contain place names and coordinates. The app asks for location only after “Use current location”, and the point is saved only if the person keeps it and saves the expense. Maps load tiles from the operator’s provider, which receives the device’s network address and the map area requested. On the phone, the app keeps a copy of the groups for offline use, and expenses and payments added offline wait there until they upload. The home screen widget shows the name of the group someone picks and their balance in it.

F-Droid

The foss build contains no proprietary libraries, so it can be built for F-Droid; its recipe has to name the foss flavor. Its built-in push distributor still uses Google’s Firebase Cloud Messaging as a network service when no other distributor is installed, which F-Droid may label as an anti-feature.