Changing state of started or joined application is deprecated....grrrr

[samuelcolvin]

Long story short

I very often want to set items on "frozen" app. I'm getting depreciation warnings for this and in future (presumably) this will fail outright. This is very frustrating.

This is made worse by pytest 3.1 which prints all warnings making this harder to ignore.

Expected behaviour

app['database'] = await create_my_database(...)

In a startup function should not cause deprecation warnings.

Actual behaviour

I'm getting warnings in lots of setups which I would have thought sensible.

Examples

in unit tests setting up a secondary server:

@pytest.fixture
def mock_external_server(loop, test_server):
    app = Application()
    app.router.add_post('/whatever.json', handler)
    server = loop.run_until_complete(test_server(app))
    app['server_name'] = f'http://localhost:{server.port}'
    return server

This causes a warning because I'm setting the server_name item on an app which is started.

using startup function:

async def startup(app: web.Application):
    app['pg_engine'] = await create_engine(pg_dsn(app['database']), loop=app.loop)

...

app = web.Application()
app.on_startup.append(startup)

(real life example here)

This again causes warnings setting pg_engine in a startup script.

Workaround

Surely this warning is wrong? If not what workaround should I use?

The only solution I can think of is an ugly bodge:

async def startup(app: web.Application):
    app['data']['pg_engine'] = await create_engine(pg_dsn(app['database']), loop=app.loop)

...

app = web.Application(middlewares=middleware)
app['data'] = {}
app.on_startup.append(startup)

[asvetlov]

Hmm.
Initial intention for 'freezing' was prevention on route table modification after initialization phase.
After that I've though that freezing global state after on_startup is also good idea.

As I see in code for run_app this sequence is supported: .freeze() is called on first server socket creation, all on_startup signals are finished at this time.

[samuelcolvin]

import pytest
from aiohttp import web


async def startup(app):
    app['foobar'] = 123


async def handle(request):
    return web.Response(text='hello')


def create_app():
    app = web.Application()
    app.on_startup.append(startup)
    app.router.add_get('/', handle)
    return app


@pytest.fixture
def cli(loop, test_client):
    app = create_app()
    return loop.run_until_complete(test_client(app))


async def test_hello(cli):
    resp = await cli.get('/')
    assert resp.status == 200
    text = await resp.text()
    assert 'o' in text

Then run

pytest --pythonwarnings=error test_example.py

gives: DeprecationWarning: Changing state of started or joined application is deprecated

[asvetlov]

The error was in aiohttp.test_utils. aiohttp.web.run_app was working as expected.
Fixed. Thanks for report.

[asvetlov]

Ooop, something is wrong with run_app too. I'll fix it.

[asvetlov]

Finally fixed

[lock]

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