0.8.2 change, new error

[jmbott]

On the latest version, 0.8.2 I am getting caught with the error, App must be running before you can run middleware!, here, but not on previous releases. Using spf as a requirement of Sanic-Cors.

Output:

Starting...
[2019-08-20 07:44:33 -0400] [66363] [DEBUG]

                 Sanic
         Build Fast. Run Fast.


[2019-08-20 07:44:33 -0400] [66363] [INFO] Goin' Fast @ http://0.0.0.0:8000
[2019-08-20 07:44:43 -0400] [66363] [ERROR] Exception occurred while handling uri: 'http://127.0.0.1:8000/'
Traceback (most recent call last):
  File ".../venv/lib/python3.7/site-packages/sanic/app.py", line 910, in handle_request
    response = await self._run_request_middleware(request)
  File ".../venv/lib/python3.7/site-packages/spf/framework.py", line 533, in _run_request_middleware
    "App must be running before you can run middleware!"
AssertionError: App must be running before you can run middleware!
[2019-08-20 07:44:43 -0400] [66363] [DEBUG] CORS: Request to '/' matches CORS resource '/*'. Using options: {'origins': ['.*'], 'methods': 'DELETE, GET, HEAD, OPTIONS, PATCH, POST, PUT', 'allow_headers': ['.*'], 'expose_headers': None, 'supports_credentials': False, 'max_age': None, 'send_wildcard': False, 'automatic_options': False, 'vary_header': True, 'resources': '/*', 'intercept_exceptions': True, 'always_send': True}
[2019-08-20 07:44:43 -0400] [66363] [DEBUG] CORS: Cannot find the request context. Is request already finished?
[2019-08-20 07:44:43 -0400] [66363] [DEBUG] CORS: Cannot find the request context. Is request already finished?
[2019-08-20 07:44:43 -0400] - (sanic.access)[INFO][127.0.0.1:54246]: GET http://127.0.0.1:8000/  500 144
[2019-08-20 07:44:48 -0400] [66363] [DEBUG] KeepAlive Timeout. Closing connection.

Python 3.7.4 (but same error with earlier versions)

sanic==19.6.2
Sanic-Cors==0.9.8.post3
Sanic-Plugins-Framework==0.8.2

Test to reproduce error:

from sanic import Sanic
from sanic.response import json
from sanic_cors import CORS

import asyncio

app = Sanic(__name__)

CORS(app, resources=r'/*')

async def hello(request):
    return json({"hello": "world"})

app.add_route(
    hello,
    '/',
    methods=['GET', 'POST']
)

def run():
    loop = asyncio.get_event_loop()
    srv_coro = app.create_server(
        host='0.0.0.0',
        port=8000,
        return_asyncio_server=True,
        asyncio_server_kwargs=None,
        debug=True
    )
    asyncio.ensure_future(srv_coro)

    try:
        loop.run_forever()
    except KeyboardInterrupt:
        loop.stop()


if __name__ == '__main__':
    print('Starting...')
    run()

[ashleysommer]

Thanks for this report.

In 0.8.2 some changes needed to be made to the order some things run, to ensure compatibility with Sanic 19.6 (particularly ASGI mode), so I'm guessing theres a side-effect of that which is causing this.

I will look into it.

[ashleysommer]

Ok, so I've found the problem.

In pre-v0.8.2, the Sanic-Plugins-Framework before-run initialisation routine was configured to run on before_server_start. This worked great until ASGI support was added. In ASGI mode, the server never runs the before_server_start trigger.

So in v0.8.2 the initialisation routine was changed to run on after_server_start which is in most cases not very different in logic, and sanic.run() and ASGI mode both support it.

Unfortunately it looks like using app.create_server() like in your example, it never triggers the after_server_start event. So Sanic-Plugins-Framework never executes its initialisation routine.

I will need raise this with the Sanic devs as a potential issue going forward, particularly for plugin creators.

As a temporary fix, you can force the run of the _on_server_start method in Sanic-Plugins-Framework, like this:

from sanic import Sanic
from sanic.response import json
from sanic_cors import CORS
from spf import SanicPluginsFramework
import asyncio

app = Sanic(__name__)
spf = SanicPluginsFramework(app)
cors = spf.register_plugin(CORS, resources=r'/*')

async def hello(request):
    return json({"hello": "world"})

app.add_route(
    hello,
    '/',
    methods=['GET', 'POST']
)

def run():
    loop = asyncio.get_event_loop()
    srv_coro = app.create_server(
        host='0.0.0.0',
        port=8000,
        return_asyncio_server=True,
        asyncio_server_kwargs=None,
        debug=True
    )
    asyncio.ensure_future(srv_coro)
    spf._on_server_start(app, loop)
    try:
        loop.run_forever()
    except KeyboardInterrupt:
        loop.stop()


if __name__ == '__main__':
    print('Starting...')
    run()

[jmbott]

Thanks @ashleysommer, I can confirm this works for my application.

[ashleysommer]

@jmbott I've created a post on the Sanic community forum about this issue.
https://community.sanicframework.org/t/triggering-after-server-start-event-when-running-asyncio-server/385
Feel free to join in.

[ashleysommer]

@jmbott
Good news, a fix for this in Sanic Core has been accepted, and will be in the next release of Sanic:
sanic-org/sanic#1676