Automatic Capacitor Android build with GitLab

How to set up a CI/CD pipeline for your Android Ionic app using fastlane and GitLab in 5 mins

Prerequisites

Before continuing with the tutorial…

Make sure you use GitLab
Your app is already deployed on Google Play store
Desire to read 😆…

Steps to follow in the post

Copy Fastline files
Storing your secrets in GitLab encrypted secrets
Creating & storing your Google Play service account key
Storing your Android signing key
Set up your GitLab workflow .yml file

1. Copy Fastline files

Fastlane is a Ruby library created to automate common mobile development tasks. Using Fastlane, you can configure custom “lanes” which bundle a series of “actions” that perform tasks that you’d normally perform using Android studio. You can do a lot with Fastlane, but for the purposes of this tutorial, we’ll be using only a handful of core actions.

Create a Fastlane folder at the root of your project and copy the following files: Fastlane

default_platform(:android)

KEYSTORE_KEY_ALIAS = ENV["KEYSTORE_KEY_ALIAS"]
KEYSTORE_KEY_PASSWORD = ENV["KEYSTORE_KEY_PASSWORD"]
KEYSTORE_STORE_PASSWORD = ENV["KEYSTORE_STORE_PASSWORD"]

platform :android do
    desc "Deploy a beta version to the Google Play"
    private_lane :verify_changelog_exists do |version_code: |
      changelog_path = "android/metadata/en-US/changelogs/#{version_code}.txt"
      UI.user_error!("Missing changelog file at #{changelog_path}") unless File.exist?(changelog_path)
      UI.message("Changelog exists for version code #{version_code}")
    end

    private_lane :verify_upload_to_staging do |version_name: |
      UI.message "Skipping staging verification step"
    end
    lane :beta do
        keystore_path = "#{Dir.tmpdir}/build_keystore.keystore"
        File.write(keystore_path, Base64.decode64(ENV['ANDROID_KEYSTORE_FILE']))
        json_key_data = Base64.decode64(ENV['PLAY_CONFIG_JSON'])
        previous_build_number = google_play_track_version_codes(
          package_name: ENV['DEVELOPER_PACKAGE_NAME'],
          track: "internal",
          json_key_data: json_key_data,
        )[0]

        current_build_number = previous_build_number + 1
        sh("export NEW_BUILD_NUMBER=#{current_build_number}")
        gradle(
          task: "clean bundleRelease",
          project_dir: 'android/',
          print_command: false,
          properties: {
            "android.injected.signing.store.file" => "#{keystore_path}",
            "android.injected.signing.store.password" => "#{KEYSTORE_STORE_PASSWORD}",
            "android.injected.signing.key.alias" => "#{KEYSTORE_KEY_ALIAS}",
            "android.injected.signing.key.password" => "#{KEYSTORE_KEY_PASSWORD}",
            'versionCode' => current_build_number
          })
        upload_to_play_store(
          package_name: ENV['DEVELOPER_PACKAGE_NAME'],
          json_key_data: json_key_data,
          track: 'internal',
          release_status: 'completed',
          skip_upload_metadata: true,
          skip_upload_changelogs: true,
          skip_upload_images: true,
          skip_upload_screenshots: true,
        )
    end
    lane :build do
      gradle(
        task: "clean bundleRelease",
        project_dir: 'android/',
        print_command: false,
        properties: {
          "android.injected.signing.store.file" => "#{keystore_path}",
          "android.injected.signing.store.password" => "#{KEYSTORE_STORE_PASSWORD}",
          "android.injected.signing.key.alias" => "#{KEYSTORE_KEY_ALIAS}",
          "android.injected.signing.key.password" => "#{KEYSTORE_KEY_PASSWORD}",
        })
    end
    lane :prod_release do
      build_gradle = File.read("../android/app/build.gradle")

      verify_changelog_exists(version_code: build_gradle.match(/versionCode (\d+)/)[1])
      verify_upload_to_staging(version_name: build_gradle.match(/versionName '([\d\.]+)'/)[1])

      supply(
        track_promote_to: 'beta',
        skip_upload_apk: true,
        skip_upload_aab: true,
        skip_upload_metadata: false,
        skip_upload_changelogs: false,
        skip_upload_images: false,
        skip_upload_screenshots: false
      )
    end
end

Storing Your Secrets in GitLab CI/CD Variables

GitLab provides a way to store encrypted CI/CD variables, similar to GitHub’s repository secrets. To store your sensitive information securely.

Go to your GitLab project’s Settings.
Navigate to CI/CD > Variables
Add the following variables:

ANDROID_KEYSTORE_FILE: the base64-encoded .jks or .keystore file used to sign your Android builds. This will either be the keystore file associated with your upload key (if using Play App Signing), or your app signing key.
KEYSTORE_KEY_PASSWORD: the password associated with the keystore file
KEYSTORE_KEY_ALIAS: the key store alias
KEYSTORE_STORE_PASSWORD: the private key password
DEVELOPER_PACKAGE_NAME: your android app ID like com.example.app
PLAY_CONFIG_JSON: The base64-encoded service account key JSON.

Set Up Your GitLab CI/CD Pipeline

Create a .gitlab-ci.yml file at the root of your project to define your CI/CD pipeline. Below is an example of how you can structure your pipeline:

image: mingc/android-build-box:latest

stages:
  - build
  - upload_to_capgo
  - build_and_upload_android

build:
  stage: build
  tags:
    - saas-linux-xlarge-amd64
  cache:
    - key:
        files:
          - bun.lockb
      paths:
        - .node_modules/
  script:
    - npm install
    - npm run build
  artifacts:
    paths:
      - node_modules/
      - dist/
  only:
    - master

upload_to_capgo:
  stage: upload_to_capgo
  tags:
    - saas-linux-xlarge-amd64
  script:
    - npx @capgo/cli@latest upload -a $CAPGO_TOKEN -c dev
  dependencies:
    - build
  when: manual
  only:
    - master

build_and_upload_android:
  tags:
    - saas-linux-xlarge-amd64
  stage:    build_and_upload_android
  cache:
    - key:
        files:
          - android/gradle/wrapper/gradle-wrapper.properties
      paths:
        - ~/.gradle/caches/
  script:
    - npx cap sync android
    - npx cap copy android
    - bundle exec fastlane android beta # We do create a tag for the build to trigger XCode cloud builds
  dependencies:
    - build
  when: manual
  only:
    - master

Trigger the Pipeline

Whenever you push a new tag to your GitLab repository, GitLab CI/CD will automatically trigger the defined pipeline, which will build and deploy your Android app using Fastlane.

Make sure to adjust the paths and dependencies according to your project’s structure and requirements. This setup will help you automate the deployment of your Android app on GitLab CI/CD.

Conclusion

By configuring GitLab CI/CD with the mingc/android-build-box Docker image, you can automate the Android app build process, making your development workflow more efficient and reliable. This automation frees up your time to focus on the core aspects of app development, ultimately helping you deliver high-quality Android apps more efficiently.