Vagrant.has_plugin? example

Vagrantfile

# Plugin-specific configurations
  if Vagrant.has_plugin?('vagrant-cachier')
    puts 'INFO:  Vagrant-cachier plugin detected. Optimizing caches.'
    config.cache.enable :chef
    config.cache.enable :apt
  else
    puts 'WARN:  Vagrant-cachier plugin not detected. Continuing unoptimized.'
  end

  if Vagrant.has_plugin?('Omnibus')
    puts 'INFO:  Vagrant-omnibus plugin detected.'
    config.omnibus.chef_version = :latest
  else
    puts "FATAL: Vagrant-omnibus plugin not detected. Please install the plugin with\n       'vagrant plugin install vagrant-omnibus' before continuing."
    exit
  end

  # This detects the Berkshelf plugin. No, seriously.
  if Vagrant.has_plugin?('berkshelf')
    # The path to the Berksfile to use with Vagrant Berkshelf
    puts 'INFO:  Vagrant-berkshelf plugin detected.'
    config.berkshelf.berksfile_path = './Berksfile'
  else
    puts "FATAL: Vagrant-berkshelf plugin not detected. Please install the plugin with\n       'vagrant plugin install vagrant-berkshelf' before continuing."
    exit
  end