distributed-tracing

Building a Distributed Trace with Service and Database Spans

A request flows through an API service and into a database, but without tracing you cannot see where the 57ms total latency comes from. This workflow creates a trace, adds a service span (45ms) and a database span (12ms) under the root, and exports all spans to Jaeger.

Workflow

requestId, operation
         |
         v
+--------------------+     +--------------------+     +----------------+     +---------------------+
| dt_create_trace    | --> | dt_service_span    | --> | dt_db_span     | --> | dt_export_trace     |
+--------------------+     +--------------------+     +----------------+     +---------------------+
  traceId generated          span-svc-...               span-db-...           exported to Jaeger
  spanId: span-root-...      durationMs: 45             durationMs: 12        destination: "jaeger"

Workers

CreateTraceWorker -- Creates a new trace for the operation. Returns a traceId and root spanId: "span-root-{timestamp}".

ServiceSpanWorker -- Adds a service span under the parent. Returns spanId: "span-svc-{timestamp}", durationMs: 45.

DbSpanWorker -- Adds a database span under the parent. Returns spanId: "span-db-{timestamp}", durationMs: 12.

ExportTraceWorker -- Exports all spans to Jaeger. Returns exported: true, destination: "jaeger".

Tests

8 unit tests cover trace creation, span recording, and trace export.

Running

See ../../RUNNING.md for setup and execution instructions.