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)
1
Part 1: Packer’s Beginnings
7
Part 2: Managing Large Environments
11
Part 3: Advanced Customized Packer

Sample plugin source

Always start with a current copy of the scaffold plugin repo. This has a few important files in the root directory, including main.go, GNUMakefile, and go.mod, which pins certain versions of the dependencies used by your Go module. It also declares a Go module, which you should rename to your module. Here, we use packer-plugin-nspawn for our module name. Have a look at the repository here: https://github.com/jboero/packer-plugin-nspawn.

The repo contains sample folders for each plugin type:

  • builder: We will use this to start a systemd-nspawn machine
  • datasource: We will use this to look up the machines and images available
  • post-processor: We won’t need one of these so we delete the directory
  • provisioner: We also won’t need one of these so we will delete it

The plugin registers itself in the very simple main.go file. Post-processors and provisioners may be added for custom actions but we won’t need anything. Packer...