A dry-system application that uses an environment variable

dry-rb-env.rb

# frozen_string_literal: true

require 'dry/system/container'
require 'dry/system/components'
require 'dry/types'

module Types
  include Dry::Types.module
end

class Application < Dry::System::Container
  use(:env)
  boot(:settings, from: :system) do
    settings do
      key :an_int, Types::Coercible::Int.default(17)
    end
  end
end

Import = Application.injector

class Main
  include Import['settings']

  def call
    puts "The magic number is #{settings.an_int}"
  end
end

Main.new.()