Use the Puppet language, or the Ruby API to create custom functions. Custom functions Puppet includes many built-in functions, and more are available in modules on the Forge. You can also write your own custom functions.Custom Puppet functionsYou can write simple custom functions in the Puppet language, to transform data and construct values. A function can optionally take one or more parameters as arguments. A function returns a calculated value from its final expression.Writing custom functions in RubyYou can write powerful and flexible functions using Ruby.Secrets store integrations and agent-side data retrievalPuppet agents can fetch or calculate data for themselves at catalog application time. One use case for this is to securely retrieve sensitive information like passwords from a secrets store.Write a Puppet function to store secretsUse the Deferred type to create a function that you add to a module to redact sensitive information.