Over the years, different modules layouts have been explored, following the evolution of Puppet's features and the refinement of usage patterns.
There has never been a unique way of doing a module, but patterns and best practices have emerged and we are going to review the most relevant ones.
The introduction of parameterized classes, with Puppet 2.6, has been a crucial step in standardizing the interfaces of classes. On earlier versions there was no unique way to pass data to a class. Variables defined anywhere could be dynamically used inside Puppet code or in templates to manage the module's behavior; there was no standard API to access or set them. We used to define parameter less classes as follows:
class apache {
# Variables used in DSL or in templates were dynamically scoped
# and referenced without using their fully qualified name.
# IE: $port, not $apache::port or $::apache_port
}To declare them always and only...