How to implement retry mechanism into python requests library?

This snippet of code will make all HTTP requests from the same session retry for a total of 5 times, sleeping between retries with an increasing backoff of 0s, 2s, 4s, 8s, 16s (the first retry is done immediately). It will retry on basic connectivity issues (including DNS lookup failures), and HTTP status codes of 502, 503 and 504.

import logging
import requests

from requests.adapters import HTTPAdapter, Retry

logging.basicConfig(level=logging.DEBUG)

s = requests.Session()
retries = Retry(total=5, backoff_factor=1, status_forcelist=[ 502, 503, 504 ])
s.mount('http://', HTTPAdapter(max_retries=retries))

s.get("http://httpstat.us/503")

See Retry class for details.

This is a snippet of code I used to retry for the petitions made with urllib2. Maybe you could use it for your purposes:

retries = 1
success = False
while not success:
    try:
        response = urllib2.urlopen(request)
        success = True
    except Exception as e:
        wait = retries * 30;
        print 'Error! Waiting %s secs and re-trying...' % wait
        sys.stdout.flush()
        time.sleep(wait)
        retries += 1

The waiting time grows incrementally to avoid be banned from server.