Support ASGI3 (#255)

daphne/cli.py

@@ -1,8 +1,11 @@
 import argparse
+import functools
 import logging
 import sys
 from argparse import ArgumentError, Namespace
 
+from asgiref.compatibility import is_double_callable
+
 from .access import AccessLogGenerator
 from .endpoints import build_endpoint_description_strings
 from .server import Server
@@ -14,6 +17,19 @@ DEFAULT_HOST = "127.0.0.1"
 DEFAULT_PORT = 8000
 
 
+class ASGI3Middleware:
+    def __init__(self, app):
+        self.app = app
+
+    def __call__(self, scope):
+        scope.setdefault("asgi", {})
+        scope["asgi"]["version"] = "3.0"
+        return functools.partial(self.asgi, scope=scope)
+
+    async def asgi(self, receive, send, scope):
+        await self.app(scope, receive, send)
+
+
 class CommandLineInterface(object):
     """
     Acts as the main CLI entry point for running the server.
@@ -113,6 +129,13 @@ class CommandLineInterface(object):
             help="The WebSocket protocols you wish to support",
             default=None,
         )
+        self.parser.add_argument(
+            "--asgi-protocol",
+            dest="asgi_protocol",
+            help="The version of the ASGI protocol to use",
+            default="auto",
+            choices=["asgi2", "asgi3", "auto"],
+        )
         self.parser.add_argument(
             "--root-path",
             dest="root_path",
@@ -227,6 +250,14 @@ class CommandLineInterface(object):
         # Import application
         sys.path.insert(0, ".")
         application = import_by_path(args.application)
+
+        asgi_protocol = args.asgi_protocol
+        if asgi_protocol == "auto":
+            asgi_protocol = "asgi2" if is_double_callable(application) else "asgi3"
+
+        if asgi_protocol == "asgi3":
+            application = ASGI3Middleware(application)
+
         # Set up port/host bindings
         if not any(
             [

setup.py

@@ -22,7 +22,7 @@ setup(
     package_dir={"twisted": "daphne/twisted"},
     packages=find_packages() + ["twisted.plugins"],
     include_package_data=True,
-    install_requires=["twisted>=18.7", "autobahn>=0.18"],
+    install_requires=["twisted>=18.7", "autobahn>=0.18", "asgiref~=3.0"],
     setup_requires=["pytest-runner"],
     extras_require={
         "tests": ["hypothesis~=3.88", "pytest~=3.10", "pytest-asyncio~=0.8"]