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Unofficial ddtrace integration for ASGI apps and frameworks

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Unofficial ddtrace integration for ASGI apps and frameworks.

Should work seamlessly for any ASGI web framework, e.g. Starlette, FastAPI, Quart, etc.

Note: This project is in alpha stage.


  • Python 3.6+.
  • ddtrace must be installed to use the ddtrace-run command.
  • The Datadog Agent must be installed and running for traces to be effectively sent to Datadog APM.


pip install ddtrace-asgi


To automatically send traces to Datadog APM on each HTTP request, wrap your ASGI application around TraceMiddleware:

from ddtrace_asgi.middleware import TraceMiddleware

async def app(scope, receive, send):
    assert scope["type"] == "http"
    headers = [[b"content-type", b"text/plain"]]
    await send({"type": "http.response.start", "status": 200, "headers": headers})
    await send({"type": "http.response.body", "body": b"Hello, world!"})

app = TraceMiddleware(
    app, service="asgi-hello-world", tags={"env": "local"},

Then use ddtrace-run when serving your application. For example, if serving with Uvicorn:

ddtrace-run uvicorn app:app

For more information on using ddtrace, please see the official dd-trace-py repository.



from ddtrace_asgi.middleware import TraceMiddleware
from starlette.applications import Starlette

app = Starlette()
app.add_middleware(TraceMiddleware, service="my-starlette-app")


from ddtrace_asgi.middleware import TraceMiddleware
from fastapi import FastAPI

app = FastAPI()
app.add_middleware(TraceMiddleware, service="my-fastapi-app")

API Reference


class TracingMiddleware:
    def __init__(self, app, tracer=None, service="asgi", tags=None, distributed_tracing=True):

An ASGI middleware that sends traces of HTTP requests to Datadog APM.


  • app - An [ASGI] application.
  • tracer - (optional) A Tracer object. Defaults to the global ddtrace.tracer object.
  • service - (optional) Name of the service as it will appear on Datadog.
  • tags - (optional) Default tags attached to all request spans. Either a dictionary, or a string of comma-separated tags (e.g. "env:staging, app:shop"). See also Tagging.
  • distributed_tracing - (optional) Whether to enable distributed tracing.


All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog.

0.3.0 - 2019-11-15


  • Allow to set default tags on all request spans. (Pull #24)

0.2.2 - 2019-11-03


  • Now ships with binary distribution (wheel) in addition to source distribution (sdist). (Pull #16)

0.2.1 - 2019-10-31


  • Improve resilience to ASGI protocol violations. (Pull #11)

0.2.0 - 2019-10-30


  • The tracer, service and distributed_tracing parameters of TraceMiddleware are now keyword-only. (Pull #10)


  • The tracer for TraceMiddleware is now the global ddtrace.tracer by default. (Pull #10)

0.1.0 - 2019-10-23

Initial release.


  • Add TracingMiddleware.

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