Book Image

Puppet 8 for DevOps Engineers

By : David Sandilands
Book Image

Puppet 8 for DevOps Engineers

By: David Sandilands

Overview of this book

As DevOps and platform engineering drive the demand for robust internal development platforms, the need for infrastructure configuration tools has never been greater. Puppet, a powerful configuration management tool, is widely used by leading enterprises and boasts a thriving open source community. This book provides a comprehensive explanation of both the Puppet language and the platform. It begins by helping you grasp the basic concepts and approach of Puppet as a stateful language, and then builds up to explaining how to structure Puppet code to scale and allow flexibility and collaboration among teams. As you advance, you’ll find out how the Puppet platform allows the management and reporting of infrastructure configuration. The book also shows you how the platform can be integrated with other tooling, such as ServiceNow and Splunk. The concluding chapters help you implement Puppet to fit in heavily regulated and audited environments as well as modern hybrid cloud environments. By the end of this book, you’ll have gained a solid understanding of the capabilities of both the Puppet language and platform, and you will have learned how to structure and scale Puppet to create a platform to provide enterprise-grade infrastructure configuration.
Table of Contents (22 chapters)
1
Part 1 – Introduction to Puppet and the Basics of the Puppet Language
7
Part 2 – Structuring, Ordering, and Managing Data in the Puppet Language
12
Part 3 – The Puppet Platform and Bolt Orchestration
17
Part 4 – Puppet Enterprise and Approaches to the Adoption of Puppet

Deferred functions

A Deferred function (also known as an agent side function) is a function with the Deferred type applied to it. This causes the function to run locally on a client when the catalog is applied, rather than on a Puppet server during compilation. The catalog for a deferred function contains what to run on the client rather than the output of the function. The deferred type was introduced in Puppet 6.0 and is available in all later versions.

This is typically used when the compilation server can’t access a necessary source in a function – for example, when retrieving a secret from a HashiCorp Vault server, where security is set up to only allow the client to access a secret.

The syntax for applying Deferred is as follows:

Deferred( name of function, [arguments])

The following is an example of retrieving a secret from vault. This can be used within a user resource for exampleapp to set the password from a Vault path of exampleapp/password:

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