A web server which fails according to known probability

flakey_server

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
#  flakey_server.py
#
#  Created by Lars Yencken on 2011-10-12.
#

"""
A web server which fails randomly and occasionally.
"""

import sys
import random

import flask

app = flask.Flask(__name__)

FAILURE_CHANCE = 0.0

@app.route('/')
def index():
    if random.random() < FAILURE_CHANCE:
        flask.abort(500)
    else:
        return 'OK'

def main():
    global FAILURE_CHANCE
    args = sys.argv[1:]
    if len(args) != 2:
        print >> sys.stderr, \
"""Usage: sometimes_fail.py <rate> <port>

Serve error responses with probability <rate> on port <port>."""
        sys.exit(1)

    rate, port = args
    port = int(port)
    rate = float(rate)
    FAILURE_CHANCE = rate
    app.run(host='0.0.0.0', port=port)

    rate = float(args[0])

if __name__ == '__main__':
    main()