Packer Fundamentals

Packer is a free and open source extensible software tool that takes your desired OS and container configurations and builds them simultaneously for the easy testing and management of complex system and application images and artifacts. If you ever find yourself in an environment where multiple custom system disks or cloud AMIs must be consistently maintained and adjusted to boot VMs or run containers, then Packer is here to simplify your life as you automate configuration through code.

This chapter is a very high-level introduction for those unfamiliar with Packer. It explains how Packer is not a service but a tool that can be manually run or inserted into an automation pipeline. It also describes how Packer can supplement Terraform to dramatically simplify anything from complex hybrid or multi-cloud deployments to on-premises private cloud or even local VMs on a development machine.

In this chapter, we will cover the following topics:

• Packer architecture, which describes how the Packer binary is distributed and developed and how Packer works with templates, builders, and provisioners at a high level
• History of Packer, which is important to understand why Packer was needed in the first place and what business problems it solves
• Who uses Packer?, which lists what types of users Packer has today, including everything from small academic labs to large-scale enterprise organizations and software vendors
• Alternatives to Packer, which is a section that describes industry alternatives and other tools that offer image management and how they compare to Packer at a high level
• Installing Packer, which covers how easy it is to install Packer on most environments, whether servers, cloud instances, or local laptops
• HCL versus JSON, which is a very high-level description of JSON and HashiCorp Configuration Language (HCL) and how Packer supports either standard for templates