Why Fastlane?

Manual deployment processes are not only tedious but prone to human error. Fastlane automates these processes, ensuring consistency and reliability in app builds and deployments. From automating screenshots and managing beta distributions to simplifying app store deployments, Fastlane offers a comprehensive suite of tools that enhance productivity and development workflow.

Moreover, Fastlane configuration is stored on a plain text file that should be added to version control, so you can share the release process and keep track of changes.

Installing Fastlane with Bundler

Introduction to Bundler

Bundler is a dependency manager for Ruby projects, ensuring that the gems you use in your project are consistently installed across all environments. Using Bundler to install Fastlane within your project’s scope avoids conflicts with system gems, providing a stable and isolated environment for your automation tasks.

Why Use Bundler for Fastlane?

Bundler manages Fastlane dependencies locally, ensuring that all project members use compatible versions, thus avoiding the “it works on my machine” syndrome. It’s a best practice for managing project-specific Ruby gems, including Fastlane.

Step-by-Step Instructions

  1. Check Ruby Installation: Ensure Ruby is installed on your system as Bundler is a Ruby gem.
  2. Install Bundler: If not already installed, use gem install bundler to install Bundler.
  3. Create a Gemfile: In your project root, create a Gemfile if one doesn’t exist and add Fastlane: 
    source 'https://rubygems.org'

gem 'fastlane'
  4. Install Fastlane: Run bundle install in your project directory. This command reads your Gemfile and installs Fastlane and its dependencies locally.
  5. Using Fastlane: Execute Fastlane commands with bundle exec, e.g., bundle exec fastlane [lane_name], to use the versions specified in your Gemfile.

Setting Up Fastlane in Your Android Project

After installing Fastlane, initialize it in your project by running fastlane init. This process generates several important files, including the Fastfile and Appfile, which are essential for configuring your Fastlane tasks.

  • Fastfile: Defines “lanes” that describe the steps to automate specific tasks.
  • Appfile: Contains global configurations for your app, like package name and API keys.

First Steps with Fastlane

Let’s create a simple lane to automate building and signing your Android app:

  1. Open the Fastfile in your project’s fastlane directory.
  2. Define a new lane called build: 
    lane :build do
  gradle(task: 'assembleRelease')
end
  3. Run your lane with bundle exec fastlane build. This command builds the release version of your app, using the configurations defined in your build.gradle file.

Which files should be checked into git?

The following files and directories created by Fastlane should be checked into your Git repository:

  • fastlane/Fastfile
  • fastlane/Appfile
  • Gemfile
  • Gemfile.lock

On the other hand, you should add .bundle directory to .gitignore.

Wrapping up

You’ve now taken your first steps with Fastlane for Android, setting up the environment and running a basic automation lane. While this post covered the essentials, there’s much more to explore with Fastlane’s extensive toolset. Stay tuned for our next post, where we’ll dive deeper into automating Android builds with Fastlane, enhancing your CI/CD pipeline for even greater efficiency.

References