osx_service - Ansible module to manage launchd services on Mac OS X

osx_service.rb

#!/usr/bin/ruby
# WANT_JSON
#
# osx_service - Ansible module to manage launchd services on Mac OS X
#
#
# The MIT License (MIT)
#
# Copyright (c) 2016 Björn Albers <bjoernalbers@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
#

require 'rubygems'
require 'json'
require 'open3'


class AnsibleModule
  attr_reader :options, :changed

  def initialize(options)
    @options = options
    @changed = false
    check_options!
  end

  def run
    apply_service_state
    output
    exit
  rescue => e
    output(msg: e.message, failed: true)
    exit(1)
  end

  def output(opts = {})
    print JSON.dump(output_hash.merge(opts))
  end
  
  def output_hash
    options.merge(changed: changed)
  end

  def service
    @service ||= Service.new(options[:name])
  end

  private

  def check_options!
    unless missing_options.empty?
      raise ArgumentError, "Missing attributes: #{missing_options.join(', ')}"
    end
  end

  def missing_options
    [:name, :state].select { |key| options[key].nil? || options[key].empty? }
  end

  def apply_service_state
    @changed =
      case options.fetch(:state).to_sym
      when :started   then service.start
      when :stopped   then service.stop
      when :restarted then service.restart
      else raise ArgumentError, 'invalid state'
      end
  end
end


class Service
  attr_reader :label

  def initialize(label)
    @label = label
  end

  def start
    stopped? ? launchctl('load', '-w', plist).run! : false
  end

  def stop
    started? ? launchctl('unload', '-w', plist).run! : false
  end

  def restart
    stop
    start
  end

  def started?
    launchctl('list', label).run
  end

  def stopped?
    !started?
  end

  private

  def launchctl(*args)
    Launchctl.new(*args)
  end

  def plist
    @plist ||= File.join('/Library/LaunchDaemons', "#{label}.plist")
  end
end


class Launchctl
  class LaunchctlError < StandardError; end

  COMMAND = '/bin/launchctl'

  def initialize(*args)
    raise LaunchctlError, 'Please run as root!' unless root?
    @args = args
  end

  def run
    run!
  rescue LaunchctlError
    false
  end

  def run!
    @stdout, @stderr, @status = Open3.capture3(COMMAND, *@args)
    raise LaunchctlError, error if failed?
    true
  end

  def failed?
    # NOTE: `launchctl` might exit successfully even when an error occurred.
    # That's why we have to check STDERR too.
    !@stderr.empty? || !@status.success? 
  end

  def error
    @stderr
  end

  private

  def root?
    Process.euid.zero?
  end
end


begin
  options = JSON.parse(File.read(ARGV.first), symbolize_names: true)
  AnsibleModule.new(options).run
rescue => e
  print JSON.dump(failed: true, msg: e.message)
  exit(1)
end

TODO: Convert to Python and ask to officially include it in ansible-modules-extras!