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

Developing provisioners with the null builder

We briefly discussed the null builder in the previous chapter. As you develop complex provisioners, it may be useful to just test them immediately without waiting for minutes—or even hours—for build environments and communicators to be ready. The null builder contains only a communicator such that there is no environment to prepare. You can use this to immediately test provisioners in a stateful environment. You can even set ssh_host to localhost if you want to test the communicator using your own machine or don’t have a lab machine available with SSH access. Here is an example where Packer will immediately connect to the local SSH service using ssh-agent so that there is no need to present keys or passwords. Packer then runs through the provisioners in order so that you can test basic functionality and syntax:

source "null" "sandbox" {
  ssh_host = "localhost"