Avoid race conditions by waiting for 200 OK on a URL.

wait.py

import datetime as dt
import time

import requests # pip install requests


def get_ok(url):
    "GET url and raise an exception if not 200 OK."
    r = requests.get(url)
    r.raise_for_status()
    return r


def wait_for_url(url, timeout=120, sleep_period=0.15, opener=get_ok):
    "Continue polling URL until 200 response or timeout (seconds) elapses."
    expiration = dt.datetime.utcnow() + dt.timedelta(seconds=timeout)
    while dt.datetime.utcnow() <= expiration:
        try:
            opener(url)
        except Exception:
            time.sleep(sleep_period)
        else:
            break