Flaxon FFD

Bridge FastAPI, Flask, and Django apps into a single Flaxon application via ASGI mounting.

Flaxon FFD is a Flaxon plugin that lets you run real, unmodified FastAPI, Flask, or Django apps side-by-side with your Flaxon app in the same process — useful for gradual migrations, reusing an existing service, or pulling in a framework-specific tool (like Django's admin, or FastAPI's auto-generated docs) without rewriting it.

from flaxon import Flaxon
from flaxon_ffd import FFDPlugin
from fastapi import FastAPI

fastapi_app = FastAPI()

@fastapi_app.get("/hello")
def hello():
    return {"hello": "world"}

app = Flaxon("main")
await app.plugins.load_plugin(FFDPlugin(mounts={"/fastapi": fastapi_app}))

GET /fastapi/hello now hits your real FastAPI route — including FastAPI's own path converters, dependency injection, and auto-generated /fastapi/docs Swagger UI, completely unmodified.

How it works

Under the hood this uses app.mount_asgi(path, foreign_app) — for any request under that path prefix, Flaxon hands the raw ASGI call straight to the mounted app's own __call__, bypassing Flaxon's routing and middleware for that subtree entirely. The mounted app handles everything itself, exactly as if it were running on its own.

What this is: running multiple independent apps together in one process, each on its own URL prefix. What this isn't: a way to use Flask/FastAPI/Django extensions as if they were native Flaxon plugins. A Flask extension mounted this way still only works inside that mounted Flask app — it doesn't become available to your Flaxon routes.

Installation

pip install flaxon-ffd[fastapi]      # for FastAPI
pip install flaxon-ffd[flask]        # for Flask (includes a2wsgi)
pip install flaxon-ffd[django]       # for Django
pip install flaxon-ffd[all]          # all three

Mounting Flask or older Django (WSGI apps)

FastAPI and Django's get_asgi_application() are already ASGI — mount them directly. Flask (and WSGI-only Django setups) need translating first, via a2wsgi:

from flask import Flask
from a2wsgi import WSGIMiddleware

flask_app = Flask(__name__)

@flask_app.route("/hello")
def hello():
    return {"hello": "world"}

app.plugins.load_plugin(FFDPlugin(mounts={
    "/flask": WSGIMiddleware(flask_app),
}))

Mounting Django

import os
os.environ.setdefault("DJANGO_SETTINGS_MODULE", "myproject.settings")
from django.core.asgi import get_asgi_application

django_app = get_asgi_application()

app.plugins.load_plugin(FFDPlugin(mounts={
    "/django": django_app,
}))

Multiple mounts at once

app.plugins.load_plugin(FFDPlugin(mounts={
    "/fastapi": fastapi_app,
    "/flask": WSGIMiddleware(flask_app),
    "/django": django_app,
}))

Requirements

• Flaxon >= 0.1.9
• Python >= 3.11

License

MIT