feat: Replace deprecated FastAPI on_event with lifespan event handlers

pyproject.toml

@@ -36,9 +36,6 @@ dev-dependencies = [
 [tool.ruff]
 line-length = 88
 
-[tool.ruff.lint.isort]
-known-first-party = ['fastapi_utils']
-
 [tool.ruff.lint.mccabe]
 max-complexity = 10
 

src/edge_proxy/server.py

@@ -1,14 +1,14 @@
 from datetime import datetime, timedelta
+import asyncio
 
 import httpx
-import structlog
+from contextlib import asynccontextmanager
 from fastapi import FastAPI, Header
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.middleware.gzip import GZipMiddleware
 from fastapi.responses import ORJSONResponse
 
 from edge_proxy.health_check.responses import HealthCheckResponse
-from fastapi_utils.tasks import repeat_every
 
 from edge_proxy.cache import LocalMemEnvironmentsCache
 from edge_proxy.environments import EnvironmentService
@@ -24,7 +24,23 @@
     httpx.AsyncClient(timeout=settings.api_poll_timeout_seconds),
     settings,
 )
-app = FastAPI()
+
+
+async def poll_environments():
+    while True:
+        await environment_service.refresh_environment_caches()
+        await asyncio.sleep(settings.api_poll_frequency_seconds)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    await environment_service.refresh_environment_caches()
+    poll = asyncio.create_task(poll_environments())
+    yield
+    poll.cancel()
+
+
+app = FastAPI(lifespan=lifespan)
 
 
 @app.exception_handler(FlagsmithUnknownKeyError)
@@ -103,16 +119,6 @@ async def get_identities(
     return ORJSONResponse(data)
 
 
-@app.on_event("startup")
-@repeat_every(
-    seconds=settings.api_poll_frequency_seconds,
-    raise_exceptions=True,
-    logger=structlog.get_logger(__name__),
-)
-async def refresh_cache():
-    await environment_service.refresh_environment_caches()
-
-
 app.add_middleware(
     CORSMiddleware,
     allow_origins=settings.allow_origins,