Creating Android Build for Flutter Apps with Custom Build Script (Part 2)

In Part 1, we focused on writing custom build scripts for an iOS app developed using Flutter. These scripts were designed to automate the process of generating the IPA (iOS App Store Package) file, which is essential for distributing the app on iOS devices. In Part 2, we will shift our focus to Android, where we will explore the process of creating build scripts for Android apps using Flutter that automate the generation of the APK (Android Package Kit) file. This will involve setting up the necessary Flutter build configuration and understanding the tools that Flutter provides to streamline the Flutter Android build process.

Creating Android Build for Flutter Apps

Step 1: Let’s build the Android project manually using the Flutter command.

Open Terminal, navigate to your Flutter project directory, and execute the following command:

flutter build apk --release

The command above should successfully generate the APK.

Step 2: Let’s develop a bash script to streamline the entire build creation process, including support for custom flavor builds.

!/bin/bash

Default values

FLAVOR="dev"

BUILD_NAME="1.0.0"

BUILD_NUMBER="1"

Clean previous builds

echo "Cleaning previous builds..."

rm -rf build/

rm -rf .dart_tool/

rm -rf .flutter-plugins

rm -rf .flutter-plugins-dependencies

Flutter clean and get dependencies

echo "Running flutter clean..."

flutter clean

echo "Getting dependencies..."

flutter pub get

...

Build Android APK

echo "Building Android APK"

...

echo "Getting dependencies..."

flutter pub get

Build command construction

BUILD_COMMAND="flutter build apk --flavor $FLAVOR -t lib/main_$FLAVOR.dart"

Add version and build number if provided

if [ ! -z "$BUILD_NAME" ]; then

BUILD_COMMAND="$BUILD_COMMAND --build-name=$BUILD_NAME"

fi

if [ ! -z "$BUILD_NUMBER" ]; then

BUILD_COMMAND="$BUILD_COMMAND --build-number=$BUILD_NUMBER"

fi

Execute build

echo "Building $FLAVOR flavor..."

echo "Executing: $BUILD_COMMAND"

eval $BUILD_COMMAND

Check if build was successful

if [ $? -eq 0 ]; then

echo "Build completed successfully!"

APK_PATH="build/app/outputs/flutter-apk/app-$FLAVOR-release.apk"

echo "APK location: $APK_PATH"

else

echo "Build failed!"

exit 1

fi

Usage :

build_android_flutter.sh -f dev -v BUILD_NAME -b BUILD_NUMBER

Version Control:

Accepts two optional parameters:
-v for version name (e.g., “1.0.0”)
-b for build number (e.g., “1”)

Flavors Specific Arguments:

-f “$FLAVOR”:

• Specifies which flavor (variant) of the app to build
• Common flavors might be ‘dev’, ‘staging’, ‘prod’

-t “lib/main_$FLAVOR.dart”:

• Specifies the entry point file for the app
• Uses different main files for different flavors
• Example: main_dev.dart, main_prod.dart

Build Process:

• Cleans previous builds using flutter clean
• Updates project dependencies with flutter pub get
• Builds the APK file with the provided flavor, version and build number

Output:

• The final APK file is created in the ./build/app/outputs/flutter-apk/ directory
• Detailed logs are displayed throughout the build process

Usage Example:

sh build_android_flutter.sh -f dev -v 1.0.0 -b 1

This above will build your Android APK for flavor dev with version 1.0.0 and build number 1. If you don’t provide these parameters, the script will use the default values (flavor=”dev”, version=”1.0.0″, build=”1″).

Note: Copy the above bash script to your Flutter project directory and ensure it has the correct permissions. Grant the script read and write access by executing the following command in your terminal:

chmod +x build_android_flutter.sh

Summing It Up

I hope you found this tutorial on Creating Android Builds for Flutter Apps with a Custom Build Script helpful. You can download the complete Flutter Android build script from here.

Source: Master Flutter Android Build: From Setup to Release