Pythonを使用してWebサイトの可用性をバッチで確認する

#!/usr/bin/env python
 
 
import pickle, os, sys, logging
from httplib import HTTPConnection, socket
from smtplib import SMTP
 
def email_alert(message, status):
 fromaddr = 'xxx@163.com'
 toaddrs = 'xxxx@qq.com'
 
 server = SMTP('smtp.163.com:25')
 server.starttls()
 server.login('xxxxx', 'xxxx')
 server.sendmail(fromaddr, toaddrs, 'Subject: %s\r\n%s' % (status, message))
 server.quit()
 
def get_site_status(url):
 response = get_response(url)
 try:
  if getattr(response, 'status') == 200:
   return 'up'
 except AttributeError:
  pass
 return 'down'
  
def get_response(url):
 try:
  conn = HTTPConnection(url)
  conn.request('HEAD', '/')
  return conn.getresponse()
 except socket.error:
  return None
 except:
  logging.error('Bad URL:', url)
  exit(1)
  
def get_headers(url):
 response = get_response(url)
 try:
  return getattr(response, 'getheaders')()
 except AttributeError:
  return 'Headers unavailable'
 
def compare_site_status(prev_results):
 
 def is_status_changed(url):
  status = get_site_status(url)
  friendly_status = '%s is %s' % (url, status)
  print friendly_status
  if url in prev_results and prev_results[url] != status:
   logging.warning(status)
   email_alert(str(get_headers(url)), friendly_status)
  prev_results[url] = status
 
 return is_status_changed
 
def is_internet_reachable():
 if get_site_status('www.baidu.com') == 'down' and get_site_status('www.sohu.com') == 'down':
  return False
 return True
 
def load_old_results(file_path):
 pickledata = {}
 if os.path.isfile(file_path):
  picklefile = open(file_path, 'rb')
  pickledata = pickle.load(picklefile)
  picklefile.close()
 return pickledata
 
def store_results(file_path, data):
 output = open(file_path, 'wb')
 pickle.dump(data, output)
 output.close()
 
def main(urls):
 logging.basicConfig(level=logging.WARNING, filename='checksites.log', 
   format='%(asctime)s %(levelname)s: %(message)s', 
   datefmt='%Y-%m-%d %H:%M:%S')
 
 pickle_file = 'data.pkl'
 pickledata = load_old_results(pickle_file)
 print pickledata
  
 if is_internet_reachable():
  status_checker = compare_site_status(pickledata)
  map(status_checker, urls)
 else:
  logging.error('Either the world ended or we are not connected to the net.')
  
 store_results(pickle_file, pickledata)
 
if __name__ == '__main__':
 main(sys.argv[1:])