Live Requests — Python

Works with any WSGI or ASGI application — Flask, Django, FastAPI and anything else that speaks those protocols. Request spans are published by the recorder's middleware from inside your server process, so there is no proxy to configure and no code change to your handlers.

Record your server

Start the server under CodeTracer instead of directly:

ct record --server --lang python -o ./trace -- flask --app app run --port 8000

Anything you would normally type after the program name still works — flags included. This is the same invocation for Django (manage.py runserver), Uvicorn, Gunicorn or a plain python app.py.

The command stays in the foreground while the server runs. Stop it with Ctrl-C; that is a normal end, not a crash, and the recording is complete when the process exits.

Watch requests arrive

In a second terminal, with the server still running:

ct replay -t ./trace

The **Requests** panel docks itself as soon as the first request lands. Send some traffic:

curl http://localhost:8000/api/users/7

A row appears for each request, showing method, route, status and duration. Double-click one to jump to the handler that served it — from there the whole time-travelling debugger is available: step backwards through the middleware that ran before your view, or forwards into the ORM call that built the response.

Open a recording later

Nothing about the recording is temporary. To reopen it after the fact:

ct replay ./trace

The panel is populated identically; only the live updates are absent.

What gets recorded

• **Route templates, not just paths.** A request to /api/users/7 is

labelled with the route it matched (/api/users/<int:user_id>), so all requests to one endpoint group together regardless of their parameters.

• **Status and duration** for every request, including ones that raised.
• **Errors.** A request that ends in an unhandled exception is marked as

failed and carries the exception message.

Requirements

Python 3.10 or newer. Nothing else — ct locates the Python recorder itself. If it cannot, it tells you exactly what is missing and how to install it rather than producing an empty recording.