183-java-observability-tracing-opentelemetry

# Java Distributed Tracing with OpenTelemetry Implement robust distributed tracing in Java with OpenTelemetry by modeling meaningful spans, preserving context propagation, and instrumenting critical business and infrastructure paths with low-overhead, privacy-safe telemetry. **What is covered in this Skill?** - OpenTelemetry tracing fundamentals for Java services - Span design: boundaries, parent/child relationships, and operation naming - Context propagation across HTTP, messaging, async tasks, and thread boundaries - Semantic conventions and stable attribute naming - Error/status/event recording best practices - Sampling strategy and performance/cost trade-offs - Privacy and security controls for trace attributes - Testing and verification of trace propagation and span correctness **Scope:** Distributed tracing quality in application and integration layers, focused on diagnosability, consistency, and operational safety. ## Constraints Tracing instrumentation must preserve context correctly and avoid leaking sensitive data. Over-instrumentation and high-cardinality attributes can harm cost and signal quality. - **PROPAGATION FIRST**: Ensure context propagation across all sync/async boundaries before adding extra span detail - **NO SENSITIVE DATA**: Never store secrets, credentials, tokens, raw payloads, or PII in span attributes/events - **LOW CARDINALITY ATTRIBUTES**: Avoid unbounded values in attributes that are used for aggregation/search - **VERIFY**: Run `./mvnw ...