puppetlabs/puppet · error · ArgumentError

Only Runtime type 'ruby' is supported, got #{type.runtime}

Error message

Only Runtime type 'ruby' is supported, got #{type.runtime}

What it means

Puppet's ClassLoader resolves a Puppet `Runtime[runtime, 'ClassName']` type reference into a live Ruby constant. Only the 'ruby' runtime is implemented: provide_from_type raises ArgumentError whenever a PRuntimeType names any other runtime, before any load is attempted. This is a hard capability limit of the PCore type system, not a missing dependency.

Source

Thrown at lib/puppet/pops/types/class_loader.rb:40

    case name
    when String
      provide_from_string(name)

    when Array
      provide_from_name_path(name.join('::'), name)

    when PAnyType, PTypeType
      provide_from_type(name)

    else
      raise ArgumentError, "Cannot provide a class from a '#{name.class.name}'"
    end
  end

  def self.provide_from_type(type)
    case type
    when PRuntimeType
      raise ArgumentError, "Only Runtime type 'ruby' is supported, got #{type.runtime}" unless type.runtime == :ruby

      provide_from_string(type.runtime_type_name)

    when PBooleanType
      # There is no other thing to load except this Enum meta type
      RGen::MetamodelBuilder::MMBase::Boolean

    when PTypeType
      # TODO: PTypeType should have a type argument (a PAnyType) so the Class' class could be returned
      #       (but this only matters in special circumstances when meta programming has been used).
      Class

    when POptionalType
      # cannot make a distinction between optional and its type
      provide_from_type(type.optional_type)

    # Although not expected to be the first choice for getting a concrete class for these
    # types, these are of value if the calling logic just has a reference to type.

View on GitHub (pinned to e227c27540)

Solutions

1. Change the runtime parameter to 'ruby' (Runtime['ruby', 'MyClass']) — no other runtime is loadable.
2. If you need a non-Ruby facility, call it from Ruby code wrapped in a Puppet function, or use an external tool, instead of a Runtime type.
3. In Ruby code that builds PRuntimeType dynamically, assert runtime == :ruby (or pass the default) before calling ClassLoader.provide.

Example fix

# before
$cls = Runtime['java', 'com.example.Thing']

# after
$cls = Runtime['ruby', 'Set']

# Ruby — before resolving a Runtime type
unless type.is_a?(Puppet::Pops::Types::PRuntimeType) && type.runtime == :ruby
  raise ArgumentError, "only Runtime['ruby', <class>] is resolvable, got #{type.runtime.inspect}"
end
Puppet::Pops::Types::ClassLoader.provide(type)

def ruby_runtime_type?(t)
  t.is_a?(Puppet::Pops::Types::PRuntimeType) && t.runtime == :ruby
end

begin
  Puppet::Pops::Types::ClassLoader.provide(rt)
rescue ArgumentError => e
  raise NotImplementedError, "runtime #{rt.runtime} not supported: #{e.message}"
end

When it happens

Trigger: Evaluating a `Runtime[...]` type whose first parameter is not 'ruby' anywhere a class must be produced: a Puppet DSL expression like Runtime['java', 'Foo'] used in a function signature or passed to ClassLoader, or Ruby code calling Puppet::Pops::Types::ClassLoader.provide(PRuntimeType.new(:java, 'Foo')).

Common situations: Copying Runtime type examples from other JVM/polyglot tooling into Puppet code; typos like Runtime['rb', ...] or 'JRUBY'; custom Ruby extensions that build PRuntimeType programmatically with a symbol other than :ruby; upstream code written against a Puppet version that was expected to gain other runtimes.

Related errors

• Init cannot be parameterized with an undefined type and addi
• Creation of new instance of type '%{type_name}' is not suppo
• The type '%{type}' does not represent a valid set of paramet
• Illegal format '#{actual}' specified for value of Runtime ty
• Data Type Load Error for type '%{type_name}': %{message}

AI-assisted analysis of puppetlabs/puppet@e227c27540 (2026-08-21). Data as JSON: /api/errors/0804d0015ba80862. Report an issue: GitHub.