while using the langfuse otel exporter, can I configure a unique id to my trace - such as my room id or callid?

Thanks for reaching out, Bharath. I'm an AI assistant and I'm here to help. Give me a moment while I research this topic.

But my room id and span id are specific to session and won't be accessible where I create the trace provider right?

You're right — if your room/call IDs are only available per session, you shouldn't (and can't) hardcode them when creating the global tracer provider. You can still attach those dynamic IDs to spans at runtime. Two common approaches: • Set attributes on each span where you have the session ID. ◦ When you start a span for a session, call

span.set_attribute("room_id", room_id)

(and

call_id

) so those attributes travel with that span and any child spans. • Propagate the session ID via context and use a span processor or middleware to add the attribute on span start. ◦ Store the session ID in the request/session context (HTTP request context, thread-local, or framework request object). ◦ Use a custom SpanProcessor or framework middleware that reads the context on span start and sets `room_id`/`call_id` automatically. Which language/SDK and web framework (if any) are you using? Tell me that and whether you want attributes applied only to root/session spans or to all child spans—I’ll provide a concise code example for your environment.

I'm using python sdk

Thanks — since you’re using the Python SDK, here are two clear, practical ways to attach per-session room/call IDs to traces at runtime. 1) Set attributes when you create spans (simple, explicit) • When you start a span for a session, add the IDs directly:

with tracer.start_as_current_span("handle_call") as span:
    span.set_attribute("room_id", room_id)
    span.set_attribute("call_id", call_id)
    # child spans inherit attributes in UI queries

Use this when you control where spans are started and only need IDs on specific spans. 2) Propagate IDs via context + custom SpanProcessor (automatic) • Store the session ID in context (contextvars) and use a SpanProcessor to read it on span start so every span gets the session attributes automatically. Example:

import contextvars
from opentelemetry.sdk.trace import SpanProcessor

# context var to hold current session ids
current_room_id = contextvars.ContextVar("room_id", default=None)
current_call_id = contextvars.ContextVar("call_id", default=None)

def set_session_ids(room, call):
    current_room_id.set(room)
    current_call_id.set(call)

class SessionSpanProcessor(SpanProcessor):
    def on_start(self, span, parent_context):
        room = current_room_id.get()
        call = current_call_id.get()
        if room:
            span.set_attribute("room_id", room)
        if call:
            span.set_attribute("call_id", call)
    def on_end(self, span):
        pass

# add processor to your tracer provider once
tracer_provider.add_span_processor(SessionSpanProcessor())

• When handling a session, call

set_session_ids(room_id, call_id)

before starting spans (e.g., at request entry). This works across async tasks and threads if you manage context appropriately. Which framework are you using (Flask, FastAPI, Django, plain asyncio)? I can give a concise example wiring this into request middleware for your framework.

contextvars isn't the right approach, suggest a alternate better way

Good point — thanks for clarifying. If

contextvars

isn't suitable, here are practical alternatives to propagate per-session room/call IDs into spans in Python, with pros/cons and a concise example request so I can tailor one to your stack. Options • Explicit per-span attributes (most straightforward) ◦ Call

span.set_attribute("room_id", room_id)

when you create the span for that session. Works everywhere, no global state, easiest to reason about. ◦ Best when you control span creation points. • OpenTelemetry Baggage (propagates across process boundaries) ◦ Use OTEL baggage to store IDs so they travel with context across threads/processes and remote calls. ◦ Use

from opentelemetry import baggage, trace

and set baggage at request entry; read it in a SpanProcessor or when creating spans. ◦ Good for cross-service tracing; slightly higher overhead. • Thread-local storage (for sync code) ◦ Use

threading.local()

to store session IDs per thread and read them in a SpanProcessor or when starting spans. ◦ Works well in synchronous servers that use one thread per request; not suitable for async/asyncio frameworks. • Request/framework-specific middleware (recommended for web apps) ◦ Attach IDs to the request object (e.g.,

request.state.room_id

in FastAPI,

g.room_id

in Flask,

request.room_id

in Django) and set span attributes in middleware or when starting spans. ◦ This avoids global context and fits idiomatically into web frameworks. Short examples • Explicit per-span:

with tracer.start_as_current_span("handle_call") as span:
    span.set_attribute("room_id", room_id)

• Baggage (set/read):

from opentelemetry import baggage

# at request entry
baggage.set_baggage("room_id", room_id)

# when starting a span
from opentelemetry import baggage as _baggage
room = _baggage.get_baggage("room_id")
span.set_attribute("room_id", room)

• Thread-local:

import threading
_ctx = threading.local()
_ctx.room_id = room_id

# in SpanProcessor.on_start or when creating spans
room = getattr(_ctx, "room_id", None)
span.set_attribute("room_id", room)

Which do you prefer or which environment are you using (FastAPI, Flask, Django, plain asyncio, or a worker process)? Tell me that and whether you want IDs on only root/session spans or on every child span — I’ll give a concise, tailored snippet and wiring advice.

I'm not starting a span manually anywhere. i'm just following langfuse's exmaple code shared in the documentation

You're right — if you never start spans manually, you still can attach per-session IDs by using OTEL baggage (set at request entry) plus a SpanProcessor that reads baggage on span start and sets `room_id`/`call_id`. This works with spans created automatically by instrumentations (including the Langfuse example). Do you use FastAPI, Flask, Django, or plain asyncio (or a worker)? Tell me which and whether you want IDs on only root/session spans or on every child span, and I’ll provide a concise, exact snippet showing where to set baggage and the SpanProcessor wiring.

I use a plain worker

Thanks — since you’re on a plain worker and spans are created automatically, use OTEL baggage plus a SpanProcessor that reads baggage on span start and sets `room_id`/`call_id`. That attaches IDs to all auto-instrumented spans without manually starting spans. Example (concise):

from opentelemetry import baggage
from opentelemetry.sdk.trace import SpanProcessor

class BaggageSpanProcessor(SpanProcessor):
    def on_start(self, span, parent_context):
        room = baggage.get_baggage("room_id", context=parent_context)
        call = baggage.get_baggage("call_id", context=parent_context)
        if room:
            span.set_attribute("room_id", room)
        if call:
            span.set_attribute("call_id", call)
    def on_end(self, span):
        pass

# once at startup
tracer_provider.add_span_processor(BaggageSpanProcessor())

When handling a session in your worker (at the point you have room/call IDs), set baggage into the current context so subsequent auto-created spans inherit it:

from opentelemetry import baggage, context

# when processing a job/session
ctx = context.set_value(baggage.set_baggage("room_id", room_id))
ctx = context.set_value(baggage.set_baggage("call_id", call_id), context=ctx)

# run the work within that context so auto-instrumentation sees it
token = context.attach(ctx)
try:
    process_job()  # work that triggers auto-created spans
finally:
    context.detach(token)

Notes and tips • This works with async or sync worker code as long as you attach the context before work that produces spans. • Baggage propagates across threads/process boundaries when using supported propagators — useful if your job dispatch forks work. • If you only want IDs on root/session spans (not every child), the SpanProcessor can check span.kind or span.parent to conditionally set attributes. Want a variant that avoids context attach/attach-detach (e.g., wrapping a job handler function) or an example integrating with your job queue? Tell me which queue/worker library you use and I’ll produce a tiny snippet.