Example of a gevent-based Flask server that aborts when downstream disconnects

abort_on_dc.py

"""
Implements a behavior similar to:
- Go srv's cancelation of context on downstream disconnect
- PHP (unless `ignore_user_abort` is true)
"""
import gevent.monkey
gevent.monkey.patch_all()

from contextlib import contextmanager
from flask import Flask
from gevent.wsgi import WSGIServer

app = Flask(__name__)


def _watchdog(reader, request_greenlet):
    data = reader.peek()
    if len(data) == 0:
        print('detected socket shutdown')
        request_greenlet.kill()


@contextmanager
def spawn_watchdog():
    from flask import request
    gr = gevent.spawn(_watchdog, request.environ['wsgi.input'].rfile, gevent.getcurrent())
    yield gr
    gr.kill()


@app.route('/')
def index():
    with spawn_watchdog():
        print('start sleep')
        gevent.sleep(2)
        print('end sleep')

    return 'Hello World'


server = WSGIServer(('127.0.0.1', 5000), app)
server.serve_forever()