OpenTelemetry
OTLP, Context Propagation & Backends
Connect the dots: how OTLP and context carry data across services to any backend.
Two mechanisms make OpenTelemetry work end to end. OTLP (the OpenTelemetry Protocol) is the standard wire format — gRPC or HTTP — for shipping traces, metrics, and logs between SDKs, Collectors, and backends. Because nearly every vendor accepts OTLP, it is the lingua franca that lets you point instrumentation at a new backend by changing an endpoint, not your code.
A shipping system where every parcel uses the same barcode standard (OTLP) and carries a tracking number passed hand to hand (context propagation), so any depot (backend) can reconstruct the parcel's entire journey.
Key Concepts
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Context propagation is what links spans across service boundaries into one trace. When service A calls service B, the SDK injects the current trace context into the request (the W3C traceparent header is the standard), and B extracts it so its spans share the same trace ID and nest under the caller. Baggage propagates arbitrary key/value context (like a tenant or request priority) the same way. The backend — Tempo, Jaeger, a vendor, or a database — then stores and reconstructs the full trace. The framing for interviews: OTel produces and propagates; OTLP transports; the backend stores and visualizes.