idaho.pp

# This function returns a boolean value based on whether or not the Puppet agent
# was invoked with --no-noop.
#
#   `puppet agent -t`           = true
#   `puppet agent -t --no-noop` = false
#
function noop::true_unless_no_noop() {
  $agent_specified_noop_setbycli ? {
    true  => $facts['agent_specified_noop'],
    false => true,
  }
}

# This function returns a boolean value representing an explicit noop setting
# for use with the noop resource metaparameter. The function considers:
#
#   * Has an override parameter been specified?
#   * Has the class-level noop parameter been set to true?
#   * Is the agent-level noop setting true?
#
function noop::explicit_metaparameter($class_noop_override, $class_level_noop) {
  $noop_override ? {
    default => $class_noop_override,
    undef   => $facts['clientnoop'] ? {
      true  => true,
      false => $class_level_noop,
    },
  }
}

# This 
class example::idaho (
  Optional[Boolean] $class_level_noop    = noop::true_unless_no_noop(),
  Optional[Boolean] $class_noop_override = undef,
) {
  # Set local scope noop defaults. WARNING: this class should now be considered
  # a "leaf" class. Do not call `include` or similar functions from this point
  # forward without careful consideration of how these scope defaults will
  # propagate. Doing so may cause unexpected side effects!
  #
  #     https://puppet.com/docs/puppet/5.3/lang_scope.html
  #     https://puppet.com/docs/puppet/5.3/lang_defaults.html
  #
  if ($class_level_noop != undef) { noop($class_level_noop) }

  # Get an explicit value for the noop metaparameter. It's necessary to do this 
  # because once we write `noop => $noop_override` on a resource in code, we
  # lose whatever the default *would* have been. The value of $noop_override
  # is calculated to be an explicit value equivalent to what value the resource
  # would recieve if the metaparameter were not passed explicitly, taking into
  # consideration both of the class-level noop adjustment parameters.
  $noop_override = noop::explicit_metaparameter($class_noop_override, $class_level_noop)

  # The noop metaparameter default is set automatically based on the scope
  # defaults invoked by the noop() function call above. The explicit equivalent
  # has been mocked in as a comment, for illustration.
  file { '/tmp/idaho1.txt':
    ensure  => file,
    content => "Content from example::idaho\nNo no-op override\n",
    # noop    => $class_level_noop,
  }

  # Enforcement of this resource may be toggled on and off by setting
  # example::idaho::class_noop_override. If no override is passed, it's end
  # behavior will be identical to the resource above.
  file { '/tmp/idaho2.txt':
    ensure  => file,
    content => "Content from example::idaho\nThere is a no-op override\n",
    noop    => $noop_override,
  }

}