Fastlane File

Fastfile

fastlane_version "2.81.0"

# Project Variables
MATCH_GIT_URL = "Match Git URL"

ios_project = {
  "name" => "App Name",
  "bundleID" => "App Bundle ID",
}

android_project = {
  "packageName" => "App Package Name",
}


def update_android_build_number(version_code)
  path = '../android/app/build.gradle'
  re = /versionCode\s+(\d+)/ 

  s = File.read(path)
  s[re, 1] = version_code.to_s

  f = File.new(path, 'w')
  f.write(s)
  f.close
end

# Otherwise the lane prints everytime is_ci? is called
ci_server = is_ci?

platform :ios do
  desc "Download and deencrypt the required keys to sign the app. Provides the option 'release' to download the release keys, e.g. 'bundle exec fastlane sign release:true', sign defaults to development keys."
  lane :sign do |options|
    MATCH_KEYCHAIN_NAME = "travisKeychain"
    MATCH_KEYCHAIN_PASSWORD = ci_server ? ENV["MATCH_PASSWORD"] : nil

    if ci_server
      create_keychain(
        name: MATCH_KEYCHAIN_NAME,
        password: MATCH_KEYCHAIN_PASSWORD,
        default_keychain: true,
        unlock: true,
        timeout: 3600,
        add_to_search_list: true,
      )
    end

    sign_for_release = ci_server || options[:release]
    match(
      git_url: MATCH_GIT_URL,
      app_identifier: [ios_project["bundleID"]],
      type: sign_for_release ? "appstore" : "development", 
      shallow_clone: sign_for_release,
      readonly: sign_for_release,
      force_for_new_devices: !sign_for_release,
      keychain_name: ci_server ? MATCH_KEYCHAIN_NAME : nil,
      keychain_password: ci_server ? MATCH_KEYCHAIN_PASSWORD : nil,
    )
  end

  desc "Build the app"
  lane :build do
    gym(
      project: "./ios/#{ios_project["name"]}.xcodeproj",
      scheme: ios_project["name"],
    )
  end

  desc "Sign the app and push a build onto testflight"
  lane :deploy do
    build_number = prompt(
      text: "Enter build number: ",
      ci_input: ENV["TRAVIS_BUILD_NUMBER"],
    )

    increment_build_number(
      xcodeproj: "./ios/#{ios_project["name"]}.xcodeproj",
      build_number: build_number,
    )

    sign(release: true)

    gym(
      project: "./ios/#{ios_project["name"]}.xcodeproj",
      scheme: ios_project["name"],
    )

    testflight(
      app_identifier: ios_project["bundleID"],
      ipa: "./#{ios_project["name"]}.ipa",
      skip_waiting_for_build_processing: true,
    )
  end
end

platform :android do
  desc "Build the app"
  lane :build do
    gradle(
      task: "assemble",
      build_type: "Release",
      project_dir: "./android/",
    )
  end

  desc "Deploy a new version to Google Play"
  lane :deploy do
    build_number = prompt(
      text: "Enter build number: ",
      ci_input: ENV["TRAVIS_BUILD_NUMBER"],
    )

    update_android_build_number(
      build_number,
    )

    gradle(
      task: "assemble",
      build_type: "Release",
      project_dir: "./android/",
    )

    apk_loc = "../android/app/build/outputs/apk/release/app-release.apk"
    json_key_loc = "./android/keys/Google_Play_Android_Developer_Key.json"
    supply(
      package_name: android_project["package_name"],
      apk: File.absolute_path(apk_loc),
      track: "beta",
      skip_upload_metadata: true,
      skip_upload_images: true,
      skip_upload_screenshots: true,
      json_key: json_key_loc,
    )
  end
end

This fast file assumes you have the following variable defined for your CI/CD environment:

MATCH_PASSWORD

This is the password you used for signing your certs in your match repo.

It also assumes that you store a Google Developers Service Account key at:

./android/keys/Google_Play_Android_Developer_Key.json

(Relative to the react native directory project directory.)
See the supply documentation on generating this key: https://docs.fastlane.tools/actions/supply/#setup