Infrastructure as Code, 2nd Edition

Chapter 13. Server Images as Code

Chapter 11 touched on the idea of creating multiple server instances from a single source (“Prebuilding Servers”), and recommended using cleanly built server images (“Creating a Clean Server Image”). If you wondered what’s the best way to follow that advice, this chapter aims to help.

As with most things in your system, you should use code to build and update server images in a repeatable way. Whenever you make a change to an image, such as installing the latest operating system patches, you can be sure you are building it consistently.

By using an automated, code-driven process to build, test, deliver, and update server images, you can more easily keep your servers up-to-date, and ensure their compliance and quality.

The basic server image life cycle involves building a custom image from an origin source (see Figure 13-1).

Figure 13-1. Server image life cycle

Building a Server Image

Most infrastructure management platforms have a format for server images to use for creating server instances. Amazon has AMIs, Azure has managed images, and VMware has VM templates. Hosted platforms provide prepackaged stock images with common operating systems and distributions so that you can create servers without needing to build images yourself.

Why Build a Server Image?

Most teams eventually build custom images rather than using the stock images from the ...