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

Seeding a file or directory into your image once booted

In our very first template, we demonstrated a simple provisioner of type file where we uploaded and replaced the /etc/motd file during the Packer build. This was uploaded over the SSH communicator using an SFTP operation. The file provisioner can actually do multiple files at once or even directories. The syntax and behavior for this are similar to rsync. Note that archived files will not be extracted automatically. Another provisioner can be used to extract an archive once it’s been uploaded. In our first example, we set content to a string we wanted to write to /etc/motd. You may also use herefile syntax to upload multiple line files as content to embed a text file inside your template. It’s usually a better idea to use the source or sources option to reference local files instead of embedding them. There are three main options for specifying your file content, as follows:

  • content: Raw text to be uploaded...