Snippet used with puppetserver irb to get info

puppetserver_irb.rb

require 'irb/completion'
require 'puppet'
Puppet.settings.preferred_run_mode = :agent # or whatever section you need

Puppet.settings.initialize_global_settings(["--config=/the/config/file"])
Puppet.settings.initialize_app_defaults(
  Puppet::Settings.app_defaults_for_run_mode(Puppet.run_mode)
)
Puppet.push_context(Puppet.base_context(Puppet.settings))

p Puppet.lookup(:environments).list.map {|env| env.to_s }