trace-context

HTTP Server with trace context propagation

Running the example

1. Run the docker compose file in the root of the repo, which will boot the OTLP collector: docker compose up

2. Run the http server by preloading the instrumentation code.

node -r "./trace-instrumentation.js" http-server.js

3. Access the app at http://localhost:8080

Explanation

The request handler function in http-server will create a log entry. Since pino is instrumented with @opentelemetry/instrumentation-pino in trace-instrumentation.js, it will also add the span context values as attributes (trace_id, span_id, trace_flags).

pino-opentelemetry-transport will read those attributes and add them to the current context. The resulting LogRecord will have those fields populated. Fields trace_id, span_id, trace_flags will not be visible in the LogRecord attributes.

Observe the logs with:

tail -f /tmp/test-logs/otlp-logs.log