Book Image

HashiCorp Packer in Production

By : John Boero
Book Image

HashiCorp Packer in Production

By: John Boero

Overview of this book

Creating machine images can be time-consuming and error-prone when done manually. HashiCorp Packer enables you to automate this process by defining the configuration in a simple, declarative syntax. This configuration is then used to create machine images for multiple environments and cloud providers. The book begins by showing you how to create your first manifest while helping you understand the available components. You’ll then configure the most common built-in builder options for Packer and use runtime provisioners to reconfigure a source image for desired tasks. You’ll also learn how to control logging for troubleshooting errors in complex builds and explore monitoring options for multiple logs at once. As you advance, you’ll build on your initial manifest for a local application that’ll easily migrate to another builder or cloud. The chapters also help you get to grips with basic container image options in different formats while scaling large builds in production. Finally, you’ll develop a life cycle and retention policy for images, automate packer builds, and protect your production environment from nefarious plugins. By the end of this book, you’ll be equipped to smoothen collaboration and reduce the risk of errors by creating machine images consistently and automatically based on your defined configuration.
Table of Contents (18 chapters)
Part 1: Packer’s Beginnings
Part 2: Managing Large Environments
Part 3: Advanced Customized Packer

Pitfalls and things to avoid

A lot of example templates in GitHub and community resources only build one item at a time. It’s actually more helpful to build everything you can in one template and run just the builds you need. Unfortunately, Packer doesn’t combine all HCL files or all files in the current directory as Terraform does. This means you need to put all sources and build combinations in one file, which can be problematic as templates grow. Unfortunately, you also can’t include or refer to other templates, which might distribute complexity among other files. What you can do is make use of HCL2’s language features.

Luckily, there are a few tools that HCL2 or JSON in Packer 1.7+ give you to simplify complex builds. Dynamic features aren’t available in JSON templates, but you can actually use the HCL2 for_each construct. for_each in HCL2 isn’t quite like any other foreach in a language you’ve used before. HCL2’s for_each...