Replace current WSGIMiddleware implementation by a2wsgi one

docs/index.md

@@ -460,6 +460,35 @@ async def app(scope, receive, send):
     })
 ```
 
+## The WSGI Support
+
+Uvicorn offer support to WSGI applications throught `WSGIMiddleware` which converts
+your WSGI into ASGI application seamlessly just by running it with `--interface wsgi`
+
+!!! warning
+    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.
+
+To use the WSGI interface install its dependency:
+
+```shell
+pip install a2wsgi
+```
+
+Create an application, in `example.py`:
+
+```python
+def app(environ, start_response):
+    start_response('200 OK', [('Content-Type', 'text/plain')])
+    return [b'Hello World!']
+```
+
+Run the server:
+
+```shell
+$ uvicorn --interface wsgi example:app
+```
+
 ---
 
 ## Why ASGI?

requirements.txt

@@ -11,6 +11,7 @@ build==0.9.0
 twine==4.0.1
 
 # Testing
+a2wsgi==1.6.0
 autoflake==1.7.7
 black==22.10.0
 flake8==3.9.2

setup.cfg

@@ -34,6 +34,7 @@ filterwarnings=
     # Turn warnings that aren't filtered into exceptions
     error
     ignore: \"watchgod\" is depreciated\, you should switch to watchfiles \(`pip install watchfiles`\)\.:DeprecationWarning
+    ignore: \"WSGIMiddleware\" is deprecated, you should switch to a2wsgi \(`pip install a2wsgi`\)\.:DeprecationWarning
     ignore: 'cgi' is deprecated and slated for removal in Python 3\.13:DeprecationWarning
 
 [coverage:run]

tests/middleware/test_wsgi.py

@@ -1,17 +1,38 @@
 import io
 import sys
-from typing import TYPE_CHECKING, AsyncGenerator, List
+from importlib import reload
+from typing import TYPE_CHECKING, AsyncGenerator, Awaitable, Callable, List
+from unittest import mock
 
 import httpx
 import pytest
 
 from uvicorn._types import Environ, StartResponse
-from uvicorn.middleware.wsgi import WSGIMiddleware, build_environ
+from uvicorn.middleware import wsgi
 
 if TYPE_CHECKING:
     from asgiref.typing import HTTPRequestEvent, HTTPScope
 
 
+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
+
+
 def hello_world(environ: Environ, start_response: StartResponse) -> List[bytes]:
     status = "200 OK"
     output = b"Hello World!\n"
@@ -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]:
     raise RuntimeError("Something went wrong")
 
 
@@ -53,56 +74,66 @@ def return_exc_info(environ: Environ, start_response: StartResponse) -> List[byt
 
 
 @pytest.mark.anyio
+@pytest.mark.parametrize("use_a2wsgi", [True, False])
+@environ_switcher
 async def test_wsgi_get() -> None:
-    app = WSGIMiddleware(hello_world)
+    app = wsgi.WSGIMiddleware(hello_world)
     async with httpx.AsyncClient(app=app, base_url="http://testserver") as client:
         response = await client.get("/")
     assert response.status_code == 200
     assert response.text == "Hello World!\n"
 
 
 @pytest.mark.anyio
+@pytest.mark.parametrize("use_a2wsgi", [True, False])
+@environ_switcher
 async def test_wsgi_post() -> None:
-    app = WSGIMiddleware(echo_body)
+    app = wsgi.WSGIMiddleware(echo_body)
     async with httpx.AsyncClient(app=app, base_url="http://testserver") as client:
         response = await client.post("/", json={"example": 123})
     assert response.status_code == 200
     assert response.text == '{"example": 123}'
 
 
 @pytest.mark.anyio
+@pytest.mark.parametrize("use_a2wsgi", [True, False])
+@environ_switcher
 async def test_wsgi_put_more_body() -> None:
     async def generate_body() -> AsyncGenerator[bytes, None]:
         for _ in range(1024):
             yield b"123456789abcdef\n" * 64
 
-    app = WSGIMiddleware(echo_body)
+    app = wsgi.WSGIMiddleware(echo_body)
     async with httpx.AsyncClient(app=app, base_url="http://testserver") as client:
         response = await client.put("/", content=generate_body())
     assert response.status_code == 200
     assert response.text == "123456789abcdef\n" * 64 * 1024
 
 
 @pytest.mark.anyio
+@pytest.mark.parametrize("use_a2wsgi", [True, False])
+@environ_switcher
 async def test_wsgi_exception() -> None:
     # Note that we're testing the WSGI app directly here.
     # The HTTP protocol implementations would catch this error and return 500.
-    app = WSGIMiddleware(raise_exception)
+    app = wsgi.WSGIMiddleware(raise_exception)
     async with httpx.AsyncClient(app=app, base_url="http://testserver") as client:
         with pytest.raises(RuntimeError):
             await client.get("/")
 
 
 @pytest.mark.anyio
+@pytest.mark.parametrize("use_a2wsgi", [True, False])
+@environ_switcher
 async def test_wsgi_exc_info() -> None:
     # Note that we're testing the WSGI app directly here.
     # The HTTP protocol implementations would catch this error and return 500.
-    app = WSGIMiddleware(return_exc_info)
+    app = wsgi.WSGIMiddleware(return_exc_info)
     async with httpx.AsyncClient(app=app, base_url="http://testserver") as client:
         with pytest.raises(RuntimeError):
             response = await client.get("/")
 
-    app = WSGIMiddleware(return_exc_info)
+    app = wsgi.WSGIMiddleware(return_exc_info)
     transport = httpx.ASGITransport(
         app=app,
         raise_app_exceptions=False,
@@ -136,6 +167,6 @@ def test_build_environ_encoding() -> None:
         "body": b"",
         "more_body": False,
     }
-    environ = build_environ(scope, message, io.BytesIO(b""))
+    environ = wsgi.build_environ(scope, message, io.BytesIO(b""))
     assert environ["PATH_INFO"] == "/文".encode("utf8").decode("latin-1")
     assert environ["HTTP_KEY"] == "value1,value2"

uvicorn/middleware/wsgi.py

@@ -2,6 +2,7 @@
 import concurrent.futures
 import io
 import sys
+import warnings
 from collections import deque
 from typing import TYPE_CHECKING, Deque, Iterable, Optional, Tuple
 
@@ -75,6 +76,11 @@ def build_environ(
 
 class WSGIMiddleware:
     def __init__(self, app: WSGIApp, workers: int = 10):
+        warnings.warn(
+            '"WSGIMiddleware" is deprecated, you should switch '
+            "to a2wsgi (`pip install a2wsgi`).",
+            DeprecationWarning,
+        )
         self.app = app
         self.executor = concurrent.futures.ThreadPoolExecutor(max_workers=workers)
 
@@ -188,3 +194,9 @@ def wsgi(self, environ: Environ, start_response: StartResponse) -> None:
         }
         self.send_queue.append(empty_body)
         self.loop.call_soon_threadsafe(self.send_event.set)
+
+
+try:
+    from a2wsgi import WSGIMiddleware  # type: ignore # noqa
+except ImportError:
+    pass