How do you create a custom function in Puppet?

Creating a custom function in Puppet involves adding Ruby files to a specific directory within the module structure. By placing these Ruby files in the <modulepath>/<modulename>/lib/puppet/parser/functions directory, you define custom functions that can be called from Puppet manifests. This approach allows you to extend Puppet's capabilities by writing reusable code that can be integrated into your Puppet manifests.

When a custom function is defined in this manner, it becomes accessible to the Puppet language, enabling you to manipulate data or perform operations not natively available within Puppet. This method leverages the flexibility of Ruby, allowing for complex logic and custom behavior tailored to the specific needs of your configuration management tasks.

The other choices do not properly align with how custom functions are structured in Puppet. Writing a Puppet script and executing it with the Puppet agent does not involve creating custom functions directly. Including a function within the main Puppet manifest is not the correct procedure, as functions need to be defined in their designated Ruby files to be reusable. Lastly, creating a module with predefined functions only does not allow for the creation of custom functions; it implies limitations to those functions already included rather than allowing for custom development.