Deploying CI/CD for Android Mobile Application with Flutter, GitHub Actions, Fastlane, and Google Play

Target

To establish a CI/CD pipeline using GitHub Actions for our existing Flutter application, supporting the following (automatically) after our preferred trigger (push on branch, create pull request, etc.):

• Setup Fastlane and all configurations related to Fastlane
• Building Android app bundle
• Incrementing Google Play Version Code
• Signing the produced packages with a given Keystore
• Deploying the packages to Google Play alpha/internal/production tracks

Fastlane Setup for Android

Installing Fastlane

Fastlane can be installed in multiple ways, but in this project, we will set up Fastlane with Bundler.

Installing Bundler

It is recommended to use Bundler and a Gemfile to define the Fastlane dependency. This clearly defines the Fastlane version and its dependencies and speeds up execution.

# Install Bundler
gem install bundler

Create a ./Gemfile in the root directory of your project with the following content:

source "https://rubygems.org"
gem "fastlane"

Run the following command:

bundle update

Add both ./Gemfile and ./Gemfile.lock to version control.

Every time you run Fastlane, use:

bundle exec fastlane [lane]

Setting Up Fastlane

Navigate to the /android directory and run:

fastlane init

Provide the package name of your application and the path for the JSON secret file downloaded from Google Play Console for your service account.

Setting Up Supply

Supply is a Fastlane tool that uploads app metadata, screenshots, and binaries to Google Play.

Collecting Google Credentials

1. Open the Google Play Console
2. Click Account Details and note the Google Cloud Project ID
3. Enable the Google Play Developer API
4. Open Service Accounts on Google Cloud
5. Create a new service account with appropriate permissions

Building Android App Bundle

Build your code in release mode to build/app/outputs/[apk][appbundle]/release directory.

Generating Your Keystore

Generate the keystore for signing the app bundle:

keytool -genkey -v -keystore my-release-key.jks -keyalg RSA -keysize 2048 -validity 10000 -alias my-key-alias

Signing Your App Bundle

Sign the output app bundle using your keystore:

jarsigner -verbose -sigalg SHA1withRSA -digestalg SHA1 -keystore my-release-key.jks app-release.aab my-key-alias

Manual Upload to Google Play

1. Sign into your Google Play Console
2. Navigate to the Testing section (internal, alpha, beta, or production)
3. Click Create Release
4. Upload your signed app bundle

Automating Version Configuration

Modify android/app/build.gradle to read version details from a version.properties file located at /android/version.properties.

Signing the APK Automatically

Instead of hardcoding keystore secrets in build.gradle, use a key.properties file inside the /android directory with the following format:

storePassword=your-store-password
keyPassword=your-key-password
keyAlias=your-key-alias
storeFile=my-release-key.jks

Fastlane Instead of Manual Deployment

Modify your /android/fastlane/Fastfile to include a lane for deployment to your desired track (alpha, beta, or production).

Example lane:

define :deploy
  supply(
    track: "alpha",
    json_key: "fastlane-secret.json",
    package_name: "com.yourapp.app"
  )
end

Deploy using:

bundle exec fastlane deploy

Automating with GitHub Actions

Create a workflow file in .github/workflows/google-play.yml.

Example steps:

1. Checkout Code

   - name: Checkout code
     uses: actions/checkout@v3

2. Set Up Flutter

   - name: Setup Flutter
     uses: subosito/flutter-action@v2

3. Deploy to Google Play using Fastlane

   - name: Deploy
     run: bundle exec fastlane deploy

Troubleshooting Guide

• Ensure you pull the latest changes before pushing a new release.
• For GitHub Organizations, add necessary permissions to the workflow YAML file.