knife plugin to set data bag attribute

version_set.rb

# This knife plugin provides the capability to set an attribute
# value in a data bag item. By default the 'versions' data bag
# is used, but that can be overridden with the -b option.
# Copy this file to ~/.chef/plugins/knife to install the plugin.

module KnifePlugins
    class DataBagVersionSet < Chef::Knife
        deps do
            require 'chef/data_bag'
        end

        banner "knife data bag version set ITEM ATTRIBUTE VALUE"
        category 'data bag'

        option :bag, :short => '-b', :long => '--bag', :description => 'The name of the versions data bag, default is: versions'

        def run
            if @name_args.length < 3
                show_usage
                ui.fatal("Please specify all arguments")
                exit 1
            end

            @data_bag_item, @attribute, @value = @name_args

            if config[:bag]
                @data_bag_name = config[:bag]
            else
                @data_bag_name = 'versions'
            end

            if @data_bag_name.nil?
                @data_bag_name = 'versions'
            end

            bag_item = Chef::DataBagItem.load(@data_bag_name, @data_bag_item)
            bag_item[@attribute] = @value
            bag_item.save

            puts "#{@data_bag_name}/#{@data_bag_item}/#{@attribute} saved."
        end
    end
end