Book Image

Extending SaltStack

Book Image

Extending SaltStack

Overview of this book

Salt already ships with a very powerful set of tools, but that doesn't mean that they all suit your needs perfectly. By adding your own modules and enhancing existing ones, you can bring the functionality that you need to increase your productivity. Extending SaltStack follows a tutorial-based approach to explain different types of modules, from fundamentals to complete and full-functioning modules. Starting with the Loader system that drives Salt, this book will guide you through the most common types of modules. First you will learn how to write execution modules. Then you will extend the configuration using the grain, pillar, and SDB modules. Next up will be state modules and then the renderers that can be used with them. This will be followed with returner and output modules, which increase your options to manage return data. After that, there will be modules for external file servers, clouds, beacons, and finally external authentication and wheel modules to manage the master. With this guide in hand, you will be prepared to create, troubleshoot, and manage the most common types of Salt modules and take your infrastructure to new heights!
Table of Contents (21 chapters)
Extending SaltStack
Credits
Foreword
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Building a serializing renderer


Renderers are reasonably easy to build, because they typically do little more than import a library, shove data through it, and then return the result. Our example renderer will make use of Python's own Pickle format.

The basic structure

Outside of any necessary imports, a renderer requires only a render() function. The most important argument is the first. As with other modules, the name of this argument is not important to Salt, so long as it is defined. Because our example uses the pickle library, we'll use pickle_data as our argument name.

Other arguments are also passed into renderers, but in our case we'll only use them for troubleshooting. In particular, we need to accept saltenv and sls, with the defaults shown later. We'll cover those in the Troubleshooting Renderers section, but for now we'll just use kwargs to cover them.

We also need to start with a special kind of import, called absolute_import, that allows us to import the pickle library from a file...