Add load_metadata_json function

This function loads the metadata.json into a puppet variable. This enables a number of neat things such as:

* Which version of the module am I using? 2.x? 3.x?
* Which author of the module am I using? puppetlabs? example42?

README.markdown

@@ -449,6 +449,17 @@ Loads a YAML file containing an array, string, or hash, and returns the data in
 
 *Type*: rvalue.
 
+#### `load_module_metadata`
+
+Loads the metadata.json of a target module. Can be used to determine module version and authorship for dynamic support of modules.
+
+ ~~~
+ $metadata = load_module_metadata('archive')
+ notify { $metadata['author']: }
+ ~~~
+
+*Type*: rvalue.
+
 #### `lstrip`
 
 Strips spaces to the left of a string. *Type*: rvalue.

lib/puppet/parser/functions/load_module_metadata.rb

@@ -0,0 +1,16 @@
+module Puppet::Parser::Functions
+ newfunction(:load_module_metadata, :type => :rvalue, :doc => <<-EOT
+ EOT
+ ) do |args|
+ raise(Puppet::ParseError, "load_module_metadata(): Wrong number of arguments, expects one") unless args.size == 1
+ mod = args[0]
+ module_path = function_get_module_path([mod])
+ metadata_json = File.join(module_path, 'metadata.json')
+
+ raise(Puppet::ParseError, "load_module_metadata(): No metadata.json file for module #{mod}") unless File.exists?(metadata_json)
+
+ metadata = PSON.load(File.read(metadata_json))
+
+ return metadata
+ end
+end

spec/functions/load_module_metadata.rb

@@ -0,0 +1,7 @@
+require 'spec_helper'
+
+describe 'load_module_metadata' do
+ it { is_expected.not_to eq(nil) }
+ it { is_expected.to run.with_params().and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
+ it { is_expected.to run.with_params("one", "two").and_raise_error(Puppet::ParseError, /wrong number of arguments/i) }
+end