How to use irb to test/debug in puppet - puppet

Question

I'm on puppet 3.6.2, I have the source for our puppet repo. I want to do this:
irb> require 'rubygems'
irb> require 'puppet'
irb> Puppet[:confdir] = "/home/wwalker/git/puppet"
irb> node=Puppet::Node.new('localhost')
irb> compiler=Puppet::Parser::Compiler.new(node)
irb> scope=Puppet::Parser::Scope.new(compiler)
irb> scope.function_generate_mysql_url(...)
However, I can't get past the compiler:
irb(main):010:0> compiler=Puppet::Parser::Compiler.new(node) Puppet::Context::UndefinedBindingError:
no 'environments' in
{:current_environment=><Puppet::Node::Environment:17836720 #name="*root*" #manifest="no_manifest" #modulepath="" >,
:root_environment=><Puppet::Node::Environment:17836720 #name="*root*" #manifest="no_manifest" #modulepath="" >}
at top of [[0, nil, nil]]
I assume I need to set the "environment", or I've set confdir wrong.
Anyone else done any testing of puppet modules in irb?
I do not have direct access to the puppet server. I've tried this on my workstation (puppet-server 4.1 installed) and on a client (puppet 3.6.2 installed).
This seems so simple, but I'm clearly missing something.
Anyone know what step(s) I'm missing?

Answer 1

I am not really sure what you are trying to accomplish but there is a puppet debugger repl for the puppet language which is very similar to pry/irb but specific to puppet.
https://github.com/nwops/puppet-debugger
You can use the debugger to run any function currently available in your module path among many other features.
You can also set a breakpoint in your puppet code and have it load the debugger using the 'debug::break()' function.
Ruby Version: 2.0.0
Puppet Version: 4.9.4
Puppet Debugger Version: 0.6.0
Created by: NWOps
Type "exit", "functions", "vars", "krt", "whereami", "facts", "resources", "classes",
"play", "classification", "types", "datatypes", "reset", or "help" for more information.
1:>> md5('sdafsd')
=> "569ebc3d91672e7d3dce25de1684d0c9"
2:>>

Answer 2

This is going to be one of those times where someone points you to another tool. If you want to do Ruby debugging, you should really think about using pry (http://pryrepl.org/) instead.
It's what I use during Puppet / modules / Ruby development and it's super simple to use.
In your Gemfile:
gem 'pry'
gem 'pry-stack_explorer'
if RUBY_VERSION =~ /^2/
gem 'pry-byebug'
else
gem 'pry-debugger'
end
Bonus: it works on Windows as well as everywhere else (DevKit may need to be installed).