Add support for lifespan state (#337)

* Add support for lifespan state

* Add lifespan state to http connection

* Add test

* Revert import changes

* Fix imports

* Fix imports

* Improve a bit the test

* Use typing_extensions.Literal

---------

Co-authored-by: Muhammad Furqan Habibi <[email protected]>

Author: Kludex

mangum/adapter.py

@@ -60,12 +60,14 @@ def infer(self, event: LambdaEvent, context: LambdaContext) -> LambdaHandler:
 
     def __call__(self, event: LambdaEvent, context: LambdaContext) -> dict[str, Any]:
         handler = self.infer(event, context)
+        scope = handler.scope
         with ExitStack() as stack:
             if self.lifespan in ("auto", "on"):
                 lifespan_cycle = LifespanCycle(self.app, self.lifespan)
                 stack.enter_context(lifespan_cycle)
+                scope.update({"state": lifespan_cycle.lifespan_state.copy()})
 
-            http_cycle = HTTPCycle(handler.scope, handler.body)
+            http_cycle = HTTPCycle(scope, handler.body)
             http_response = http_cycle(self.app)
 
             return handler(http_response)

mangum/protocols/lifespan.py

@@ -4,6 +4,7 @@
 import enum
 import logging
 from types import TracebackType
+from typing import Any
 
 from mangum.exceptions import LifespanFailure, LifespanUnsupported, UnexpectedMessage
 from mangum.types import ASGI, LifespanMode, Message
@@ -63,6 +64,7 @@ def __init__(self, app: ASGI, lifespan: LifespanMode) -> None:
         self.startup_event: asyncio.Event = asyncio.Event()
         self.shutdown_event: asyncio.Event = asyncio.Event()
         self.logger = logging.getLogger("mangum.lifespan")
+        self.lifespan_state: dict[str, Any] = {}
 
     def __enter__(self) -> None:
         """Runs the event loop for application startup."""
@@ -82,7 +84,7 @@ async def run(self) -> None:
         """Calls the application with the `lifespan` connection scope."""
         try:
             await self.app(
-                {"type": "lifespan", "asgi": {"spec_version": "2.0", "version": "3.0"}},
+                {"type": "lifespan", "asgi": {"spec_version": "2.0", "version": "3.0"}, "state": self.lifespan_state},
                 self.receive,
                 self.send,
             )
@@ -101,7 +103,7 @@ async def receive(self) -> Message:
         if self.state is LifespanCycleState.CONNECTING:
             # Connection established. The next event returned by the queue will be
             # `lifespan.startup` to inform the application that the connection is
-            # ready to receive lfiespan messages.
+            # ready to receive lifespan messages.
             self.state = LifespanCycleState.STARTUP
 
         elif self.state is LifespanCycleState.STARTUP:

tests/test_lifespan.py

@@ -4,9 +4,11 @@
 from quart import Quart
 from starlette.applications import Starlette
 from starlette.responses import PlainTextResponse
+from typing_extensions import Literal
 
 from mangum import Mangum
 from mangum.exceptions import LifespanFailure
+from mangum.types import Receive, Scope, Send
 
 
 @pytest.mark.parametrize(
@@ -209,6 +211,54 @@ async def app(scope, receive, send):
         handler(mock_aws_api_gateway_event, {})
 
 
+@pytest.mark.parametrize(
+    "mock_aws_api_gateway_event,lifespan",
+    [(["GET", None, None], "auto"), (["GET", None, None], "on")],
+    indirect=["mock_aws_api_gateway_event"],
+)
+def test_lifespan_state(mock_aws_api_gateway_event, lifespan: Literal["on", "auto"]) -> None:
+    startup_complete = False
+    shutdown_complete = False
+
+    async def app(scope: Scope, receive: Receive, send: Send):
+        nonlocal startup_complete, shutdown_complete
+
+        if scope["type"] == "lifespan":
+            while True:
+                message = await receive()
+                if message["type"] == "lifespan.startup":
+                    scope["state"].update({"test_key": b"Hello, world!"})
+                    await send({"type": "lifespan.startup.complete"})
+                    startup_complete = True
+                elif message["type"] == "lifespan.shutdown":
+                    await send({"type": "lifespan.shutdown.complete"})
+                    shutdown_complete = True
+                    return
+
+        if scope["type"] == "http":
+            await send(
+                {
+                    "type": "http.response.start",
+                    "status": 200,
+                    "headers": [[b"content-type", b"text/plain; charset=utf-8"]],
+                }
+            )
+            await send({"type": "http.response.body", "body": scope["state"]["test_key"]})
+
+    handler = Mangum(app, lifespan=lifespan)
+    response = handler(mock_aws_api_gateway_event, {})
+
+    assert startup_complete
+    assert shutdown_complete
+    assert response == {
+        "statusCode": 200,
+        "isBase64Encoded": False,
+        "headers": {"content-type": "text/plain; charset=utf-8"},
+        "multiValueHeaders": {},
+        "body": "Hello, world!",
+    }
+
+
 @pytest.mark.parametrize("mock_aws_api_gateway_event", [["GET", None, None]], indirect=True)
 def test_starlette_lifespan(mock_aws_api_gateway_event) -> None:
     startup_complete = False