Observability: Grafana, Logs & Traces

Observability is the ability to understand what is happening inside a system from the telemetry it emits — enough to debug problems you did not anticipate, not just the ones you set alerts for. It rests on three signals: metrics (aggregatable numbers over time), logs (discrete timestamped events), and traces (the causal path of one request across services). Each answers a different question, and the real skill is knowing which to reach for.

Metrics are the province of the Prometheus track; this track covers everything around them. It grounds the RED and USE methods, then goes deep on the other two pillars: structured logging and how Grafana Loki stays cheap by indexing labels instead of full text, and distributed tracing — spans, context propagation, and head- vs tail-based sampling with backends like Tempo and Jaeger.

It ties the picture together with OpenTelemetry — the vendor-neutral standard for producing telemetry, its Collector pipeline and OTLP — and Grafana, the layer where you visualize and alert on all of it. Spaced repetition keeps the concepts sharp for when you are on call and need them most.