Observability and Distributed Tracing for Modern Apps

Observability helps teams understand how an app behaves in real life. It uses three pillars: metrics, traces, and logs. Metrics give numbers for latency, throughput, and error rate. Traces show how a request travels across services. Logs provide context about events and decisions. Together, they help you see the health of your system and spot issues fast.

Distributed tracing maps the path of a request across microservices. Each request starts a trace with multiple spans for work done by different services. For example, a user opening a page may go through a frontend, an API gateway, an auth service, a database call, and a cache. The trace helps you see which step added delay or failed.

Key ideas:

  • Propagate a trace context with every call. The trace id ties logs and traces together.
  • Use standard headers like traceparent to carry context, and baggage for extra data.
  • A tracing backend stores and shows traces. OpenTelemetry can collect data and export to Jaeger, Tempo, or cloud services.
  • Correlate traces with logs by including trace_id and span_id in log lines.

How to start:

  • Choose a toolchain. OpenTelemetry is a good, vendor-neutral option.
  • Instrument core paths first. Auto-instrument where possible, then add manual spans for custom work.
  • Decide on sampling. Full sampling gives complete data but costs more; discuss thresholds with your team.
  • Link logs and traces. Include trace_id in logs for easy cross-reference.
  • Build simple dashboards. Track latency by service, error rates, and the number of active traces. Set alerts for SLO breaches.

Best practices:

  • Start small, iterate, and skip over-collection.
  • Use structured, consistent log formats to reduce noise.
  • Review incidents with traces in postmortems to learn and improve.

As teams grow, observability becomes an everyday tool, not a one-time project. Clear traces reduce mean time to recovery and help engineers communicate faster with non-technical teammates.

Key Takeaways

  • Observability uses metrics, traces, and logs to understand apps.
  • Distributed tracing shows request paths across services and helps find bottlenecks.
  • Start with OpenTelemetry, link logs and traces, and set clear SLOs.