Waiting for a remote network service

Sometimes, during the recovery of a network service, it might be useful to run a script to check when the server is online again.

How to do it...

We can write a client that will wait for a particular network service forever or for a timeout. In this example, by default, we would like to check when a web server is up in localhost. If you specified some other remote host or port, that information will be used instead.

Listing 3.3 shows waiting for a remote network service, as follows:

#!/usr/bin/env python 
# Python Network Programming Cookbook, Second Edition -- Chapter - 3 
# This program is optimized for Python 2.7.12 and Python 3.5.2. 
# It may run on any other version with/without modifications. 
 
import argparse 
import socket 
import errno 
from time import time as now 
 
DEFAULT_TIMEOUT = 120 
DEFAULT_SERVER_HOST = 'localhost' 
DEFAULT_SERVER_PORT = 80 
 
class NetServiceChecker(object): 
    """ Wait for a network service to come online""" 
    def...