when 'openstack'
            raise 'OpenStack options are missing' unless options.has_key?(:openstack)
            raise "Invalid OpenStack options, Hash expected, #{options[:openstack].class} given" unless options[:openstack].is_a?(Hash)
            raise 'OpenStack authorization URL is missing' unless options[:openstack].has_key?(:openstack_auth_url)
            raise 'OpenStack user name is missing' unless options[:openstack].has_key?(:openstack_username)