Replace current WSGIMiddleware implementation by a2wsgi one #1825

humrochagf · 2022-12-31T00:41:03Z

Hello!

This should fix issue #371
And this is also a continuation of PR #1303

Closes WSGI middleware should stream request body, rather than loading it all at once. #371
Relates to Document Uvicorn as a WSGI & ASGI webserver. #177
Relates to Use a2wsgi.WSGIMiddleware replace WSGIMiddleware #1303

humrochagf · 2022-12-31T00:52:08Z

I kept most of wsgi tests as a backwards compatibility validation, and that's also why I kept the wsgi module, to avoid breaking someone importing it directly.

If that's not needed I can drop the module and the tests for it and move it inside the config as the previous PR was.

I also added a test for the missing module case since in #177 there was no adhesion to push towards wsgi feature so I understood it as an optional feature, that is part of the [standard] package and not the minimal one.

Kludex · 2022-12-31T13:16:17Z

I know I said this, but did you check what is needed for us to just solve #371 without adding a2wsgi as optional dependency?

I'd like to explore that option if it's not that complicated.

btw, I invited you to encode. Thanks for all the help here. 👍

humrochagf · 2022-12-31T15:15:52Z

Hey, sure what is required for the fix is a rework of how the body is handled to stream the payload instead of loading it into memory.

@euri10 did this change in #1049 PR.

And thanks for inviting me to encode looking forward to help more with uvicorn 😃

Kludex · 2022-12-31T15:19:01Z

@euri10 did this change in #1049 PR.

Hmm... That has a footprint that I believe it would be worth it just replacing to a2wsgi. Is all that needed?

And thanks for inviting me to encode looking forward to help more with uvicorn 😃

😎 👍

humrochagf · 2022-12-31T17:24:36Z

Yup, all there, also tested running a django/takahe instance replacing fully gunicorn by uvicorn and doing some image uploads and everything is running fine

Kludex · 2022-12-31T17:26:08Z

I'm not sure if I was clear. I mean: is it possible to achieve a fix with less footprint?

humrochagf · 2022-12-31T18:28:53Z

Oh okay, I can try some things, but for sure we need a body that streams content on demand, I'll write a small test scenario with a bigfile that is more reproducible than trying things manually and try to reduce the scope of this change.

humrochagf · 2022-12-31T21:10:07Z

Yeah, there is not much that can be done to reduce footprint.

WSGI expects a file like structure in the wsgi.input, so we need to have that bridge between the async reader and the sync file like stream to deliver the body without preload the content in memory and explode the pod with big file uploads.

Another viable path to follow is a deprecation warning on wsgi interface + adding a pluggable interface option + docs on how to plug a2wsgi if maintaining wsgi isn't a focus of uvicorn.

Kludex · 2022-12-31T21:22:05Z

I'll see this tomorrow. Thanks!

Feliz ano novo Humberto! 😁

humrochagf · 2022-12-31T22:35:51Z

Alright!

Feliz ano novo pra vc tb 😁

Kludex

@abersheeran If you have time, can you check if this is fine?

Kludex · 2023-01-06T09:13:12Z

pyproject.toml

@@ -36,6 +36,7 @@ dependencies = [

 [project.optional-dependencies]
 standard = [
+    "a2wsgi>=1.6.0,<2.0.0",


Let's add a2wsgi as uvicorn dependency, and change the documentation as mentioned on #1303 (comment).

Notes about this decision:

a2wsgi is less than 15kB.

a2wsgi is already the recommended WSGIMiddleware on Starlette.

Yeah, is fine. 😊

So the change will be the move from optional dependencies to the base dependecies, is that it?

Yes, and to add on the documentation that Uvicorn is also a WSGI server.

Et voilà 🙂

Since WSGIMiddleware converts WSGI into ASGI I described it as an ASGI first web server what do you think?

Kludex · 2023-01-07T22:45:05Z

I gave a bit more thought about this.

This is what I suggest us to do:

Don't add a2wsgi as a dependency. Instead, ask the user to download a2wsgi if needed.
Don't remove uvicorn's WSGIMiddleware, but deprecate it, mentioning that people should install a2wsgi.
Add a logic to check if a2wsgi is installed (just import), and if it's use it. If not, use the one from uvicorn.
Don't change documentation in regard to Uvicorn being a WSGI server.

The idea here is to not add another minimal dependency - as we always want to avoid this as much as possible - and to not break our users.

What do you think @humrochagf ?

humrochagf · 2023-01-07T23:56:49Z

Sounds good 🙂

humrochagf · 2023-01-08T15:09:04Z

uvicorn/middleware/wsgi.py

+try:
+    from a2wsgi import WSGIMiddleware  # type: ignore # noqa
+except ImportError:
+    pass


Not the most attractive solution, but it's the best option to deprecate it without touching the config module since for testing purposes we can't reload the config module import table without breaking unrelated tests that share the config module state.

It also keeps backward compatibility with someone importing it directly in code.

Suggested change

try:

from a2wsgi import WSGIMiddleware # type: ignore # noqa

except ImportError:

pass

try:

from a2wsgi import WSGIMiddleware # type: ignore # noqa

except ModuleNotFound:

WSGIMiddleware = _WSGIMiddleware

humrochagf · 2023-01-08T15:19:51Z

I think it's all there, the only weird thing is that when running uvicorn command without a2wsgi I don't see the deprecation warning, but pytest detects it.

Is there any kind of filter to not log it in terminal?

Update: If I change the filter in my client code to show it, then I can see the deprecation warning:

import warnings
warnings.simplefilter("always")

Kludex

I'm not so sure about the documentation.

Can we just add a small note on https://www.uvicorn.org/settings/#application-interface mentioning that the user should install a2wsgi for WSGI support, and that the Uvicorn's native WSGI integration is deprecated?

uvicorn/middleware/wsgi.py

Kludex · 2023-01-08T15:26:36Z

uvicorn/middleware/wsgi.py

+try:
+    from a2wsgi import WSGIMiddleware  # type: ignore # noqa
+except ImportError:
+    pass


Suggested change

try:

from a2wsgi import WSGIMiddleware # type: ignore # noqa

except ImportError:

pass

try:

from a2wsgi import WSGIMiddleware # type: ignore # noqa

except ModuleNotFound:

WSGIMiddleware = _WSGIMiddleware

Kludex · 2023-01-08T15:30:38Z

tests/middleware/test_wsgi.py

+def environ_switcher(
+    async_test: Callable[[], Awaitable[None]]
+) -> Callable[[bool], Awaitable[None]]:
+    from uvicorn.middleware import wsgi
+
+    async def test_wrapper(use_a2wsgi: bool) -> None:
+        if use_a2wsgi:
+            await async_test()
+        else:
+            with mock.patch.dict(sys.modules, {"a2wsgi": None}):
+                reload(wsgi)
+
+                await async_test()
+
+            reload(wsgi)
+
+    return test_wrapper
+
+


Now we do this, and avoid the @environ_switcher magic, and the individual parametrize on each test.

Suggested change

def environ_switcher(

async_test: Callable[[], Awaitable[None]]

) -> Callable[[bool], Awaitable[None]]:

from uvicorn.middleware import wsgi

async def test_wrapper(use_a2wsgi: bool) -> None:

if use_a2wsgi:

await async_test()

else:

with mock.patch.dict(sys.modules, {"a2wsgi": None}):

reload(wsgi)

await async_test()

reload(wsgi)

return test_wrapper

@pytest.fixtures(param=wsgi._WSGIMiddleware, a2wsgi.WSGIMiddleware)

def wsgi_middleware_class(request):

return request.param

Done, much better now 😄

Kludex · 2023-01-08T15:31:11Z

tests/middleware/test_wsgi.py

@@ -34,7 +55,7 @@ def echo_body(environ: Environ, start_response: StartResponse) -> List[bytes]:
    return [output]


-def raise_exception(environ: Environ, start_response: StartResponse) -> RuntimeError:
+def raise_exception(environ: Environ, start_response: StartResponse) -> List[bytes]:


I understand why you did this, but I don't think it's the right type. It should be NoReturn 🤔

From the typechecker perspective WSGIMiddleware expects a function that has List[bytes] as return type, if it aways fails into exception is not that important.

This type error started to be more clear because the a2wsgi WSGIMiddleware is less permissive in terms of functions it accepts.

Kludex · 2023-01-08T15:32:11Z

docs/index.md

+Uvicorn offer support to WSGI applications throught `WSGIMiddleware` which converts
+your WSGI into ASGI application seamlessly just by running it with `--interface wsgi`


Is this the first mention to the WSGIMiddleware on the documentation? I think this is just an implementation detail.

Also cut it and put just the mention in the settings like you said

Kludex · 2023-01-08T15:33:04Z

docs/index.md

+    The present WSGIMiddleware will be deprecated in favour of [a2wsgi](https://github.com/abersheeran/a2wsgi).
+    If you are using Uvicorn to run WSGI applications, please add it as part of your project requirements.


It will be removed, but this PR already deprecates it.

Suggested change

The present WSGIMiddleware will be deprecated in favour of [a2wsgi](https://github.com/abersheeran/a2wsgi).

If you are using Uvicorn to run WSGI applications, please add it as part of your project requirements.

The present WSGIMiddleware is deprecated in favour of [a2wsgi](https://github.com/abersheeran/a2wsgi).

If you are using Uvicorn to run WSGI applications, please add it as part of your project requirements.

Yup, updated the docs

Kludex · 2023-01-08T15:33:55Z

docs/index.md

+Run the server:
+
+```shell
+$ uvicorn --interface wsgi example:app


Is the --interface needed, or does uvicorn infers it? I never used WSGI with uvicorn. 🤔

It fails to infer it, maybe a bug but it falls into asgi2 case that also uses a function instead of a coroutine in the config code:

... elif inspect.isfunction(self.loaded_app): use_asgi_3 = asyncio.iscoroutinefunction(self.loaded_app) ...

humrochagf · 2023-01-08T16:23:57Z

ok, I'll need to stop for today, tomorrow I'll fix what is missing

humrochagf · 2023-01-09T23:10:26Z

Alright!
I think I checked everything 🙂

humrochagf · 2023-01-10T13:01:35Z

Just saw your test simplification, didn't knew fixtures could behave like parametrize

humrochagf · 2023-01-10T15:44:43Z

Done, updated the tests with the code simplification

Kludex · 2023-01-10T15:53:40Z

I'm on the phone, but I can comment some stuff.

There are two things that I think we can improve before merging:

Improve the warning message. I think the user shouldn't be aware that uvicorn has an entity called "WSGIMiddleware". Maybe something like "uvicorn's native WSGI implementation is deprecated in favor of a2wsgi package. Please install it with pip install a2wsgi." - or something like that.
We can specify which "# type: ignore[here]". There's an option on mypy to make this mandatory, that we have on starlette already. And the noqa I believe it can be removed? 🤔

Besides this, everything is cool here. Sorry for the round-trips here.

humrochagf · 2023-01-11T14:28:22Z

Oh, no worries and all done 🙂

Had to ignore 2 kinds of type error codes:

uvicorn/middleware/wsgi.py:202: error: Cannot assign to a type  [misc]
uvicorn/middleware/wsgi.py:202: error: Incompatible types in assignment (expression has type "Type[_WSGIMiddleware]", variable has type "Type[WSGIMiddleware]")  [assignment]

Kludex

Thanks @humrochagf 🙏

Feel free to merge it :)

humrochagf · 2023-01-16T12:47:40Z

Yay, can I delete the branch after the merge as well?

Kludex · 2023-01-16T12:56:18Z

It's in your fork anyway 👀

humrochagf · 2023-01-16T13:04:33Z

Oh right, the way the ui presented it I thought it had a branch copy in encode/uvicorn side 😜

Kludex requested changes Jan 6, 2023

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Kludex added the wsgi label Jan 6, 2023

Kludex added this to the Version 0.21.0 milestone Jan 6, 2023

humrochagf added 2 commits January 6, 2023 08:14

Replace current WSGIMiddleware implementation by a2wsgi one

0e40358

Move a2wsgi to base dependencies and update docs accordingly

c0b5bdd

humrochagf force-pushed the a2wsgi branch from dc1366b to c0b5bdd Compare January 6, 2023 13:15

Kludex added the waiting author Waiting for author's reply label Jan 7, 2023

humrochagf added 6 commits January 7, 2023 20:08

Revert wsgi removal

c5b071f

Revert tests and deprecate WSGIMiddleware

f91bc36

Update tests to validate lib and non lib cases

1c9a510

Add a2wsgi to testing requirements

27edadd

Fix typo in requirements

124946c

Add deprecation warning

da713f3

humrochagf commented Jan 8, 2023

View reviewed changes

Kludex requested changes Jan 8, 2023

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humrochagf added 2 commits January 8, 2023 10:40

Update docs

19ca8d4

Revert index docs and add note to settings interface

594733c

Update middleware with code change sugested

0350c10

humrochagf added 2 commits January 9, 2023 09:58

Remove import magic in tests

f471027

Update error message

d2512bb

Simplify tests

87406c4

Better wording in error and type ignores

0db9f30

Kludex approved these changes Jan 16, 2023

View reviewed changes

humrochagf merged commit 2351d5f into encode:master Jan 16, 2023

humrochagf deleted the a2wsgi branch January 16, 2023 13:04

		Uvicorn offer support to WSGI applications throught `WSGIMiddleware` which converts
		your WSGI into ASGI application seamlessly just by running it with `--interface wsgi`

		The present WSGIMiddleware will be deprecated in favour of [a2wsgi](https://github.com/abersheeran/a2wsgi).
		If you are using Uvicorn to run WSGI applications, please add it as part of your project requirements.

Replace current WSGIMiddleware implementation by a2wsgi one #1825

Replace current WSGIMiddleware implementation by a2wsgi one #1825

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