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Integrating with application frameworks
=======================================
WSGI
----
To integrate APScheduler with web frameworks using WSGI_ (Web Server Gateway Interface),
you need to use the synchronous scheduler and start it as a side effect of importing the
module that contains your application instance::
from apscheduler.schedulers.sync import Scheduler
def app(environ, start_response):
"""Trivial example of a WSGI application."""
response_body = b"Hello, World!"
response_headers = [
("Content-Type", "text/plain"),
("Content-Length", str(len(response_body))),
]
start_response(200, response_headers)
return [response_body]
scheduler = Scheduler()
scheduler.start_in_background()
Assuming you saved this as ``example.py``, you can now start the application with uWSGI_
with:
.. code-block:: bash
uwsgi --enable-threads --http :8080 --wsgi-file example.py
The ``--enable-threads`` (or ``-T``) option is necessary because uWSGI disables threads
by default which then prevents the scheduler from working. See the
`uWSGI documentation <uWSGI-threads>`_ for more details.
.. note::
The :meth:`.schedulers.sync.Scheduler.start_in_background` method installs an
:mod:`atexit` hook that shuts down the scheduler gracefully when the worker process
exits.
.. _WSGI: https://wsgi.readthedocs.io/en/latest/what.html
.. _uWSGI: https://www.fullstackpython.com/uwsgi.html
.. _uWSGI-threads: https://uwsgi-docs.readthedocs.io/en/latest/WSGIquickstart.html#a-note-on-python-threads
ASGI
----
To integrate APScheduler with web frameworks using ASGI_ (Asynchronous Server Gateway
Interface), you need to use the asynchronous scheduler and tie its lifespan to the
lifespan of the application by wrapping it in middleware, as follows::
from apscheduler.schedulers.async_ import AsyncScheduler
async def app(scope, receive, send):
"""Trivial example of an ASGI application."""
if scope["type"] == "http":
await receive()
await send(
{
"type": "http.response.start",
"status": 200,
"headers": [
[b"content-type", b"text/plain"],
],
}
)
await send(
{
"type": "http.response.body",
"body": b"Hello, world!",
"more_body": False,
}
)
elif scope["type"] == "lifespan":
while True:
message = await receive()
if message["type"] == "lifespan.startup":
await send({"type": "lifespan.startup.complete"})
elif message["type"] == "lifespan.shutdown":
await send({"type": "lifespan.shutdown.complete"})
return
async def scheduler_middleware(scope, receive, send):
if scope['type'] == 'lifespan':
async with AsyncScheduler() as scheduler:
await app(scope, receive, send)
else:
await app(scope, receive, send)
Assuming you saved this as ``example.py``, you can then run this with Hypercorn_:
.. code-block:: bash
hypercorn example:scheduler_middleware
or with Uvicorn_:
.. code-block:: bash
uvicorn example:scheduler_middleware
.. _ASGI: https://asgi.readthedocs.io/en/latest/index.html
.. _Hypercorn: https://gitlab.com/pgjones/hypercorn/
.. _Uvicorn: https://www.uvicorn.org/
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