puppet apply custom function - ruby

Question

How can I quickly run a custom function on any node with puppet apply ?
Let's say I have this file (test.pp)
file { "/root/files/f":
content => test('test'),
}
And this ruby file (test.rb) which only log and return the first agument.
require 'logger'
module Puppet::Parser::Functions
newfunction(:test, :type => :rvalue
) do |args|
log = Logger.new(STDOUT)
log.level = Logger::INFO
log.info(args[0])
args[0]
end
end
How does one call the ruby function test with a puppet apply test.pp?
My problem is that is take like 5minutes to run my entire puppet agent -t and I need to add a function to puppet so I would like to test it quickly instead of waiting 5minutes each time.

Answer 1

This will certainly work, but it's hard to maintain.
A more maintainable way to do this is to add your function to a module, then install that module on your master.
For example, create a new with the name of your module (eg. test_function):
mkdir -p test_function/lib/puppet/parser/functions
You should have the following tree in your test_function module
├── lib
│   └── puppet
│   ├── parser
│   │   └── functions
│   │   ├── test.rb
Add your test.rb code to the test.rb file
Copy this module to your master's module path (this is probably /etc/puppet/modules depending on your Puppet version, use puppet module list to find out)
After that, the puppet master will read its module list and dynamically add-in all functions it finds.
More documentation about it here:
https://docs.puppetlabs.com/guides/plugins_in_modules.html
https://docs.puppetlabs.com/guides/custom_functions.html

Answer 2

I just found out.
All you need to do is to add the test.rb file directly into /var/lib/puppet/lib/puppet/parser/functions/test.rb and the puppet apply will "see" the function.