appconfig_toggle.rb

class Main
  require 'aws-sdk-appconfigdata'

  def initialize(application:, environment:, profile:)
    @application = application
    @environment = environment
    @profile     = profile

    @client = Aws::AppConfigData::Client.new(
      region:            'ap-northeast-1',
      access_key_id:     'XXXX',
      secret_access_key: 'XXXXXXXX'
    )
  end

  def toggle_value(key)
    # TODO: cache the result
    config = JSON.parse(configuration.configuration.read)

    if config.key?(key)
      config.dig(key, 'enabled')
    else
      raise 'no such key!'
    end
  end

  private

  def configuration
    @client.get_latest_configuration(
      configuration_token: session.initial_configuration_token
    )
  end

  def session
    @client.start_configuration_session({
      application_identifier:                    @application,
      environment_identifier:                    @environment,
      configuration_profile_identifier:          @profile,
      required_minimum_poll_interval_in_seconds: 15
    })
  end
end

client = Main.new(
  application: 'novelly',
  environment: 'development',
  profile:     'default'
)

puts client.toggle_value('use_macos_fonts')    # -> true/false