Traces and OpenTelemetry

Every request, GraphQL operation, gRPC call, MCP call, LLM call, tool call, script and evaluation becomes a span in an OpenTelemetry-shaped trace (32-hex trace ids, 16-hex span ids, parent spans, attributes and status). The Traces view lists them, newest first, and shows the selected trace as a waterfall with each span's input, output and attributes. Secret values are redacted before a trace is written. Filter the list by text or kind, or tick Errors for the traces that ended in an error. An HTTP or GraphQL request's span has its phases as children: DNS lookup, TCP connect and TLS handshake (lighter, on a new connection), waiting for the first byte, and download (green).

A trace's header names the request it came from and its History entry (or its run), and a click opens them; a trace's right-click menu (the same as its ⋯) has Open, the run it belongs to and Copy link. A Console line links to its trace the same way. See Finding your way around.

Test runs keep the traces of failing tests (--trace failures, the default); --trace all keeps every test's trace and --trace none none.

Send traces to OpenTelemetry

TestPion exports traces as OTLP/HTTP JSON to any OpenTelemetry-compatible backend: an OpenTelemetry Collector, Jaeger, Grafana Tempo, Honeycomb, Datadog, New Relic and others. Spans keep their ids, parents and timings; attributes stay attributes; inputs and outputs are added as testpion.input / testpion.output (redacted, at most 4 KB each); the resource is service.name = testpion with the run's id and name.

From the CLI (CI pipelines)

Give the collector with --otlp, or set the standard OpenTelemetry variables, and the traces of testpion test, testpion run and testpion run-collection are sent during the run:

# a local collector or Jaeger (OTLP/HTTP listens on 4318)
testpion test tests/ --trace all --otlp http://localhost:4318

# the standard variables work too, e.g. for Honeycomb
export OTEL_EXPORTER_OTLP_ENDPOINT=https://api.honeycomb.io
export OTEL_EXPORTER_OTLP_HEADERS="x-honeycomb-team=$HONEYCOMB_API_KEY"
testpion run-collection "Veterinary API" --trace all

--otlp-header key:value adds headers (for example an API key). OTEL_EXPORTER_OTLP_TRACES_ENDPOINT (a full URL) and OTEL_EXPORTER_OTLP_TRACES_HEADERS are honoured as well. If the collector can't be reached, the run prints a warning and its result doesn't change.

To try it locally, run Jaeger and open its UI on port 16686:

docker run --rm -p 16686:16686 -p 4318:4318 jaegertracing/all-in-one

From the app

In the Traces view, the send button next to Refresh opens Send to OpenTelemetry: enter the collector URL and headers, then send the selected trace or all the traces shown (filter first to narrow them down). Put an API key in a secret variable and use it as {{honeycombKey}}: only variable references are remembered, never a typed-in key.

For AI agents

The export_traces MCP tool sends the newest traces (optionally of one kind) to a collector.