Did you know the Java Instrumentation API has existed since Java 5? It's a legal way to peek inside the JVM, and it's the foundation both Byte Buddy and the OpenTelemetry Java agent are built on.

What if you could add real instrumentation to a legacy or vendor application without touching its code? Ten years ago, most Java applications weren't built with observability in mind: barely any logs, hardly metrics (except JMX), no traces, just darkness.

I'll show you how the Instrumentation API and Byte Buddy work together, how the OpenTelemetry Java agent uses them under the hood, and how to build your own custom extension on top of it, all to get deep insights about the running application.
In a live demo I will show how to intercept method calls, create distributed traces, and emit custom metrics with a custom OpenTelemetry extension.

You'll leave with working code you can apply to that legacy system no one wants to touch.