Run the app as ASGI

api/Dockerfile

@@ -115,8 +115,7 @@ EXPOSE 8000
 # Wait for ES to accept connections
 ENTRYPOINT ["./run.sh"]
 
-# gunicorn configuration in gunicorn.conf.py
-CMD ["gunicorn"]
+CMD ["python", "run.py"]
 
 #########
 # NGINX #

api/Pipfile

@@ -46,6 +46,7 @@ redlock-py = "~=1.0"
 requests-oauthlib = "~=1.3"
 sentry-sdk = "~=1.30"
 django-split-settings = "*"
+uvicorn = {extras = ["standard"], version = "*"}
 
 [requires]
 python_version = "3.11"

api/conf/asgi.py

@@ -0,0 +1,16 @@
+import os
+
+import django
+
+from conf.asgi_handler import OpenverseASGIHandler
+
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "conf.settings")
+
+
+def get_asgi_application():
+    django.setup(set_prefix=False)
+    return OpenverseASGIHandler()
+
+
+application = get_asgi_application()

api/conf/asgi_handler.py

@@ -0,0 +1,75 @@
+import asyncio
+import inspect
+import logging
+import weakref
+from collections.abc import Callable
+
+from django.core.handlers.asgi import ASGIHandler
+
+
+parent_logger = logging.getLogger(__name__)
+
+
+class OpenverseASGIHandler(ASGIHandler):
+    """
+    Extend default ASGIHandler to implement lifetime hooks.
+
+    Handlers are registered by calling `register_shutdown_handler`.
+    The class maintains only weak references to handler functions
+    and methods to prevent memory leaks. This removes the need
+    for explicit deregistration of handlers if, for example, their associated
+    objects (if a method) or contexts are garbage collected.
+
+    Asynchronous handlers are automatically supported via `async_to_sync`
+    and do not need special consideration at registration time.
+    """
+
+    logger = parent_logger.getChild("OpenverseASGIHandler")
+
+    def __init__(self):
+        super().__init__()
+        self._on_shutdown: list[weakref.WeakMethod | weakref.ref] = []
+
+    def _clean_ref(self, ref):
+        self.logger.info("Cleaning up a ref")
+        self._on_shutdown.remove(ref)
+
+    def register_shutdown_handler(self, handler: Callable[[], None]):
+        """Register an individual shutdown handler."""
+        if inspect.ismethod(handler):
+            ref = weakref.WeakMethod(handler, self._clean_ref)
+        else:
+            ref = weakref.ref(handler, self._clean_ref)
+
+        self._on_shutdown.append(ref)
+
+    async def __call__(self, scope, receive, send):
+        if scope["type"] == "lifespan":
+            while True:
+                message = await receive()
+                if message["type"] == "lifespan.startup":
+                    await send({"type": "lifespan.startup.complete"})
+
+                elif message["type"] == "lifespan.shutdown":
+                    await self.shutdown()
+                    await send({"type": "lifespan.shutdown.complete"})
+                    return
+
+        await super().__call__(scope, receive, send)
+
+    async def shutdown(self):
+        live_handlers = 0
+
+        for handler_ref in self._on_shutdown:
+            if not (handler := handler_ref()):
+                self.logger.debug("Reference dead, skipping handler")
+                continue
+
+            live_handlers += 1
+
+            if asyncio.iscoroutinefunction(handler):
+                await handler()
+            else:
+                handler()
+
+        self.logger.info(f"Executed {live_handlers} handler(s) before shutdown.")

api/conf/settings/base.py

@@ -60,8 +60,6 @@
     },
 ]
 
-WSGI_APPLICATION = "conf.wsgi.application"
-
 # Default primary key field type
 # https://docs.djangoproject.com/en/4.2/ref/settings/#default-auto-field
 

api/run.py

@@ -0,0 +1,21 @@
+import os
+
+import uvicorn
+
+
+if __name__ == "__main__":
+    uvicorn.run(
+        "conf.asgi:application",
+        host="0.0.0.0",
+        port=8000,
+        reload=os.getenv("ENVIRONMENT") == "local",
+        log_level="debug",
+        log_config={
+            "version": 1,
+            "formatters": {
+                "generic": {
+                    "format": "[%(asctime)s - %(name)s - %(lineno)3d][%(levelname)s] %(message)s",  # noqa: E501
+                },
+            },
+        },
+    )

docker-compose.yml

@@ -236,7 +236,6 @@ services:
       - api/.env
     stdin_open: true
     tty: true
-    command: gunicorn --reload -w 1
 
   ingestion_server:
     profiles: