Infrastructure as Code, 2nd Edition

Chapter 21. Safely Changing Infrastructure

The theme of making changes frequently and quickly runs throughout this book. As mentioned at the very start (“Objection: “We must choose between speed and quality””), far from making systems unstable, speed is an enabler for stability, and vice versa. The mantra is not “move fast and break things,” but rather, “move fast and improve things.”

However, stability and quality don’t result from optimizing purely from speed. The research cited in the first chapter shows that trying to optimize for either speed or quality achieves neither. The key is to optimize for both. Focus on being able to make changes frequently, quickly, and safely, and on detecting and recovering from errors quickly.

Everything this book recommends—from using code to build infrastructure consistently, to making testing a continuous part of working, to breaking systems into smaller pieces—enables fast, frequent, and safe changes.

But making frequent changes to infrastructure imposes challenges for delivering uninterrupted services. This chapter explores these challenges and techniques for addressing them. The mindset that underpins these techniques is not to see changes as a threat to stability and continuity, but to exploit the dynamic nature of modern infrastructure. Exploit the principles, practices, and techniques described throughout this book to minimize disruptions from changes.

Reduce the Scope of Change

Agile, XP, Lean, and similar approaches optimize the speed ...