Add apt repos for use with wright (WIP)

add_apt_repo.rb

# Add an apt repo from wright scripts.
#
# Example:
#
# AddAptRepo.new(
#   self,
#   name: 'docker',
#   key_id: '36A1D7869245C8950F966E92D8576A8BA88D21E9',
#   raw_line: "deb https://get.docker.com/ubuntu docker main"
# ).call
#
class AddAptRepo
  attr_reader :wright, :name, :raw_line, :key_id, :keyserver

  def initialize(wright, opts)
    @wright    = wright
    @name      = opts.fetch(:name)
    @raw_line  = opts.fetch(:raw_line)
    @key_id    = opts.fetch(:key_id)
    @keyserver = opts.fetch(:keyserver, 'hkp://keyserver.ubuntu.com:80')
  end

  public
  def call
    create_keyfile
    create_listfile
  end

  def create_keyfile
    wright.directory(File.dirname gpg_key_filename)
    wright.file(gpg_key_filename) { |f| f.mode = '444' }

    File.size(gpg_key_filename) > 0 or
      fetch_gpg_key
  end

  def create_listfile
    wright.file list_filename do |f|
      f.content = raw_line+"\n"
      f.mode = '444'
      f.on_update = -> { system 'apt-get', 'update' }
    end
  end

  def gpg_key_filename
    "/etc/apt/trusted.gpg.d/#{name}.gpg"
  end

  def fetch_gpg_key
    cmd = [
           'apt-key',
           '--keyring', gpg_key_filename,
           'adv',
           '--keyserver', keyserver,
           '--recv-keys', key_id
          ]

    system(*cmd) or fail("Error fetching key #{key_id}")
  end

  def list_filename
    "/etc/apt/sources.list.d/#{name}.list"
  end
end