Observability Engineering, 2nd Edition

Part I. Introduction to Observability

This first segment lays the foundations that the rest of the book builds on.

You’ll learn what observability actually means in the context of software development, how AI changes that picture, and how to gauge how observable your system really is. You’ll also learn what investigative capabilities a high degree of observability unlocks, and how to test whether your system actually has them.

Chapter 1 traces where the term “observability” came from, how it was adapted for software systems, and what it actually means to have an observable system. It also looks at how to think about observability in the age of AI-assisted development and agentic applications.

Chapter 2 is about how code crosses over from development into production, and what it takes to do that well. It describes the full “test in prod” toolkit—instrumentation, feature flags, canaries, automated rollbacks—as a flywheel where each practice enables the next. And it makes the case that all of it depends on one thing first: observability that is rich and precise enough to actually trust.

Chapter 3 is a retrospective on the evolution of observability, written by coauthor Charity Majors from her own perspective. It focuses on the lessons that matter most now that “observability” has become ubiquitous, and closes with the functional requirements that anchor the concepts introduced throughout this part of the book.

In Part II, we’ll introduce you to instrumentation principles and OpenTelemetry. ...