The easiest way to do this is to use environment variables:
Use Appfileas follows:
apple_id ENV["APPLE_ID"] || "default@company.com"
app_identifier ENV["APP_IDENTIFIER"] || "com.company.default"
When you now call fastlane without environment variables:
fastlane beta
it will use the default values provided ( default@company.com)
to set another value that you can use
APP_IDENTIFIER="com.custom.app" fastlane enterprise
, , .