OpenTelemetry

OpenTelemetry is the layer that generates and transports telemetry. It does not replace Loki, Prometheus, Tempo or Grafana: it makes applications and libraries produce signals with a common model and delivers them to the backends that store them.

From code to backends

Automatic instrumentation can observe known operations such as an HTTP request or a database query. A business operation such as generating a report can use a manually created span:

Span span = tracer.spanBuilder("report.generate").startSpan();
try (Scope ignored = span.makeCurrent()) {
  generateReport(reportId);
} finally {
  span.end();
}

OpenTelemetry handles three parts of the journey:

1. Instrumentation generates the signals. Automatic libraries and manual code create spans, metrics or logs and add common data such as service.name="report-worker".
2. The SDK prepares the telemetry. It maintains context between operations and passes the signals to an exporter, usually through the OTLP format.
3. The Collector distributes them. It receives OTLP and sends each signal to the appropriate backend: logs to Loki, metrics to Prometheus and traces to Tempo.

application -> instrumentation -> SDK -> OTLP -> Collector -> backends

The Collector prevents every application from having to know all destinations. Not every signal must pass through it: logs can leave through stdout, and Prometheus can collect metrics directly. OpenTelemetry provides a common model; it does not impose a single architecture.

What to instrument

Start with automatic instrumentation and add manual code only for operations that provide meaning, such as report.generate. Keep names and attributes consistent across services; changing backends is easier than correcting telemetry that never shared the same context.