Puppet apply only specific classes

If you want to apply Puppet changes in an selective manner you can run

puppet apply -t --tags Some::Class

on the client node to only run the single class named "Some::Class". Why does this work? Because Puppet automatically creates tags for all classes you have. Ensure to upper-case all parts of the class name, because even if you actual Ruby class is "some::class" the Puppet tag will be "Some::Class".