Tracing Propagation

[lilianskim]

Is there a way to set the trace id received from an external source e.g., request header?

[yonib05]

Hi @lilianskim, yes, this works with standard OpenTelemetry context propagation. Apologies for the slow answer on what turns out to be good news.

Strands parents its invoke_agent span on the current OTel context, so if you attach the incoming trace context before invoking the agent, all agent, model, and tool spans nest under the external trace id.

If the caller sends a W3C traceparent header, extract and attach it around the agent call:

from opentelemetry import context
from opentelemetry.propagate import extract

ctx = extract(dict(request.headers))
token = context.attach(ctx)
try:
    result = agent("hello")
finally:
    context.detach(token)

If you're on FastAPI, Flask, or similar, the corresponding OpenTelemetry instrumentation package (for example opentelemetry-instrumentation-fastapi) does this extraction automatically, so any agent invoked inside a request handler picks up the incoming trace with no extra code. If your external source only gives you a raw trace id rather than a full traceparent header, you can build the carrier yourself as {"traceparent": f"00-{trace_id}-{span_id}-01"} and pass it to extract. Just make sure the span_id part is a nonzero 16-hex value, since the propagator silently discards a traceparent with an all-zero span id.

General tracing setup is covered here: traces. Hope this helps!