CORS stops working after a while

[sourav-paul]

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Example Code

from fastapi import FastAPI
//from fastapi.middleware.cors import CORSMiddleware // tried this one before
from starlette.middleware.cors import CORSMiddleware // mentioned in GitHub issues for similar issues

app = FastAPI()

origins = [
    "http://our_s3_host.com",
    "https://our_s3_host.com",
    "http://localhost",
    "http://localhost:8080",
]

app.add_middleware(
    CORSMiddleware,
    allow_origins=origins,
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


@app.get("/")
async def main():
    return {"message": "Hello World"}

Description

The frontend app is hosted in the AWS S3 bucket. FastAPI backend is running on AWS App Runner service, which runs containerized apps.

The setup works immediately and keeps on working for a while (not absolutely sure for how long). Then stops working the next day with the same setup. After redeploying, it starts working immediately. And stops after a while.

Started using starlette.middleware.cors instead of fastapi.middleware.cors, the issue persists.

Operating System

Linux, Other

Operating System Details

AWS App Runner

FastAPI Version

0.95.1

Pydantic Version

1.10.4

Python Version

3.11.4

Additional Context

No response