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

Using an IDE to guide templates

What would a JSON version of our first template look like? JSON is important because a lot of source material from the community and GitHub is still written in legacy JSON. In fact, JSON has some advantages and disadvantages, so you may want to start with JSON when writing your template and convert it to HCL later. There is no tool within Packer to convert HCL2 to pkr.json or legacy JSON, so when a JSON option is required, it’s best to start with pkr.json syntax and not legacy JSON. Only legacy JSON to HCL2 templates can be migrated with Packer’s built-in tool. This can be installed from GitHub or via the go command:

go install github.com/hashicorp/hcl/v2/cmd/hcldec@latest

Schemas are very helpful when building JSON templates. A JSON schema is simply a specialized JSON document that declares the desired format of another JSON document. Schemas are not available from the Packer engineering team, but Community versions are available...