Over the past decade, observability has gone from a niche discipline talked about at events like Monitorama or Velocity (RIP) to a multibillion-dollar industry that touches every part of the cloud native world. The key to effective observability, though, is high-quality telemetry data. OpenTelemetry is a project that aims to provide this data and, in doing so, kick off the next generation of observability tools and practices.

If you’re reading this book, it’s highly likely that you’re an observability practitioner—perhaps a developer or an SRE—who is interested in how to profile and understand complex systems in production. You may have picked it up because you’re interested in what OpenTelemetry is, how it fits together, and what makes it different from historical monitoring frameworks. Or maybe you’re just trying to understand what all the hype is about. After all, in just five years, OpenTelemetry has gone from an idea to one of the most popular open source projects in the world. Regardless of why you’re here, we’re glad you came.

Our goal in writing this book was not to create a “missing manual” for OpenTelemetry—you can find lots of documentation and tutorials and several other fantastic books that dive deep into implementing OpenTelemetry in specific languages (see Appendix B for details on those). Our goal was to present a comprehensive guide to learning OpenTelemetry itself. We want you to understand not just what the different parts are but how they fit together and why. This book should equip you with the foundational knowledge you’ll need not only to implement OpenTelemetry in a production system but also to extend OpenTelemetry itself—either as a contributor to the project or by making it part of an organizational observability strategy.

In general, this book has two main parts. In Chapters 1 through 4, we discuss the current state of monitoring and observability and show you the motivation behind OpenTelemetry. These chapters help you understand the foundational concepts that underpin the entire project. They’re invaluable not just for first-time readers but for anyone who’s been practicing observability for a while. Chapters 5 through 9 move into specific use cases and implementation strategies. We discuss the “how” behind the concepts introduced in earlier chapters and give you pointers on actually implementing OpenTelemetry in a variety of applications and scenarios.

If you’re already well versed in observability topics, you might be considering skipping ahead to the latter part of the book. While we can’t stop you, you’ll probably get something out of reviewing the initial chapters. Regardless, as long as you go into this book with an open mind, you should get something out of it—and keep coming back, time after time. We hope this book becomes the foundation for the next chapter of your observability journey.