Build and sign Flutter app with Github Actions

build.gradle

// android/app/build.gradle
def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

def keystoreProperties = new Properties()
def keystorePropertiesFile = rootProject.file('key.properties')
if (keystorePropertiesFile.exists()) {
    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 30

    // compileOptions {
    //     sourceCompatibility JavaVersion.VERSION_1_8
    //     targetCompatibility JavaVersion.VERSION_1_8
    // }

    // kotlinOptions {
    //     jvmTarget = '1.8'
    // }

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.myflutter.app"
        minSdkVersion 21
        targetSdkVersion 30
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    lintOptions {
        checkReleaseBuilds false
    }

    signingConfigs {
        if (System.getenv("ANDROID_KEYSTORE_PATH")) {
            release {
                storeFile file(System.getenv("ANDROID_KEYSTORE_PATH"))
                keyAlias System.getenv("ANDROID_KEYSTORE_ALIAS")
                keyPassword System.getenv("ANDROID_KEYSTORE_PRIVATE_KEY_PASSWORD")
                storePassword System.getenv("ANDROID_KEYSTORE_PASSWORD")
            }
        } else {
            release {
                keyAlias keystoreProperties['keyAlias']
                keyPassword keystoreProperties['keyPassword']
                storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
                storePassword keystoreProperties['storePassword']
            }
        }
    }

    buildTypes {
        release {
            signingConfig signingConfigs.release
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
        debug {
            signingConfig signingConfigs.debug
            shrinkResources false
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}

build.yml

name: Flutter CI

# This workflow is triggered on pushes to the repository.

on:
  push:
    tags:
    - v[0-9]+.[0-9]+.[0-9]+

# on: push    # Default will running for every branch.

jobs:
  build:
    # This job will run on ubuntu virtual machine
    runs-on: ubuntu-latest
    env:
      DNAME: ${{ secrets.DNAME }} # example: "CN=com.myflutter.app, OU=MyFlutter, O=App, L=United States, ST=New York, C=US"
      ANDROID_KEYSTORE_PATH: ${{ secrets.ANDROID_KEYSTORE_PATH }} # root directory of jks file
      ANDROID_KEYSTORE_ALIAS: ${{ secrets.ANDROID_KEYTORE_ALIAS }}
      ANDROID_KEYSTORE_PRIVATE_KEY_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PRIVATE_KEY_PASSWORD }}
      ANDROID_KEYSTORE_PASSWORD: ${{ secrets.ANDROID_KEYSTORE_PASSWORD }}
    steps:

    # Setup Java environment in order to build the Android app.
    - uses: actions/checkout@v1
    - uses: actions/setup-java@v1
      with:
        java-version: '12.x'

    # Setup the flutter environment.
    - uses: subosito/flutter-action@v1
      with:
        channel: 'stable' # 'dev', 'alpha', default to: 'stable'
        # flutter-version: '1.12.x' # you can also specify exact version of flutter
    - name: Build and sign Flutter app
      run: |
        
        # Generate signature
        keytool -genkey -noprompt \
          -alias $ANDROID_KEYSTORE_ALIAS \
          -dname $DNAME \
          -keystore $ANDROID_KEYSTORE_PATH \
          -storepass $ANDROID_KEYSTORE_PRIVATE_KEY_PASSWORD \
          -keypass $ANDROID_KEYSTORE_PASSWORD \
          -keyalg RSA \
          -keysize 2048 \
          -validity 365 # days
          
        
        # Get flutter dependencies.
        flutter pub get
      
        # Check for any formatting issues in the code.
        flutter format --set-exit-if-changed .
      
        # Statically analyze the Dart code for any errors.
        flutter analyze .

        # Run widget tests for our flutter project.
        flutter test

        # Build apk.
        flutter build apk

    # Upload generated apk to the artifacts.
    - uses: actions/upload-artifact@v1
      with:
        name: release-apk
        path: build/app/outputs/apk/release/app-release.apk