Request correlation

Kong's correlation-id plugin sets X-Request-Id. Services accept a client-supplied id only when it matches [A-Za-z0-9._:-]{1,64}. The value is copied to MDC traceId, to the error body field traceId, to event_outbox.trace_id, to IntegrationEventEnvelope.traceId, and to inbox_messages.trace_id.

Promtail reads the JSON field and Kong access logs so a single id is searchable from the edge to the consumer. Full procedure: Correlation and tracing.