When a single user request hits 10+ microservices, traditional logs are useless. You need traces.
A trace is a single request's end-to-end journey, made up of multiple spans (one span per service or operation). Each span has timing data, parent-child relationships, and tags.
Common tools:
- OpenTelemetry (OTel) — the open standard for instrumentation. Replaces older OpenTracing and OpenCensus
- Jaeger / Tempo — open-source trace storage and UI
- AWS X-Ray — managed tracing on AWS
- Datadog APM — commercial APM with built-in tracing