Graceful shutdown of a FastAPI application using uvicorn

README.md

Gracefully Shutting Down Uvicorn running FastAPI Application

The key libraries to achieve graceful shutting down to a Uvicorn server running a FastAPI application are the built in os and signal modules. Given an endpoint with which a client can request the server to shutdown.

os.kill(os.getpid(), signal.SIGTERM)

os.getpid() retrieves the running process' system ID and then signal.SIGINT is passed to the process to signal an interrupt.

Links:

• os.kill
• SIGINT

client.py

import requests

if __name__ == '__main__':
    print(requests.get('http://localhost:8000/hello').content)
    print(requests.get('http://localhost:8000/shutdown').content)

server.py

import os
import signal
import fastapi
import uvicorn

from fastapi.responses import JSONResponse

app = fastapi.FastAPI()

def hello():
    return fastapi.Response(status_code=200, content='Hello, world!')

def shutdown():
    os.kill(os.getpid(), signal.SIGTERM)
    return fastapi.Response(status_code=200, content='Server shutting down...')

@app.on_event('shutdown')
def on_shutdown():
    print('Server shutting down...')

app.add_api_route('/hello', hello, methods=['GET'])
app.add_api_route('/shutdown', shutdown, methods=['GET'])

if __name__ == '__main__':
    uvicorn.run(app, host='localhost', port=8000)