Spring Boot Metrics, Traces, and Instrumentation

Own what the service emits and what those signals are allowed to mean: meter names and tag budgets, where instrumentation goes, how observations become both metrics and spans, and which signals justify an SLO. Actuator already produces a large useful baseline; most of this skill is deciding what to add and what to delete.

When to use

• A metric, span, or dashboard is missing, wrong, or too expensive to store.
• Choosing between a manual Timer, Observation, and @Observed for a code path.
• Tag or label cardinality is growing, or a time series is missing from the backend.
• Traces stop at a thread boundary, a message, or an outbound call.
• Deciding which signal maps to which SLO and alert, or reviewing instrumentation across layers.

When not to use