python_pinger.git

1) #!/usr/bin/python3
2) #
3) # Since this is meant to be run as a daemon, do not use #!/usr/bin/env python3,
4) # because the process name would then be python3, not based on __FILE__.
5) #
6) # [filename] -d 3 192.168.1.1 192.168.1.12 &
7) # disown [jobid]
8) import os
9) import sys
10) import subprocess
11) import time
12) from argparse import ArgumentParser
13) import threading
14) import queue

15) import signal

16) 

17) pinger_lock = threading.Lock()
18) 

19) 

20) def log_exit(sig, frame):
21)     _print_queue.put([f'{time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())} '
22)                       f'PID={os.getpid()} signal={signal.Signals(sig).name} Exiting.'])

23)     _print_queue.join()
24)     sys.exit(0)
25) 
26) 

27) def pinger():
28)     """Each queue item is a new address to ping. Ping and compare and print.
29)     Issue: Each of these threads reads from and writes to the global _results dict.
30)     """
31)     while True:
32)         host = _ping_queue.get()
33)         now = time.localtime()
34)         success = ping(host)

35)         with pinger_lock:
36)             # Access to _results needs to be serialized
37)             need_update = success != _results[host]
38)             if need_update:
39)                 _results[host] = success
40)         if need_update:

41)             status = "UP" if success else "DOWN"
42)             _print_queue.put([f'{time.strftime("%Y-%m-%d %H:%M:%S", now)} {host} {status}'])
43)         _ping_queue.task_done()
44) 
45) 
46) def ping(host):
47)     """Returns True if host (str) responds to a ping request."""
48)     return subprocess.call([*_ping_cmd, host], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL) == 0
49) 
50) 
51) def print_manager():
52)     """The only thread allowed to write output."""
53)     while True:
54)         job = _print_queue.get()
55)         for line in job:
56)             log(line)
57)         _print_queue.task_done()
58) 
59) 
60) def log(*args, **kwargs):
61)     """Opens the logfile, writes the log, and closes the logfile."""
62)     # I don't leave the log file open for writing because another process needs access too.
63)     with open(_logname, 'a') as fp:
64)         return print(*args, **kwargs, file=fp)
65) 
66) 
67) if __name__ == '__main__':
68)     parser = ArgumentParser(description="Repeatedly ping sites. Ex: %(prog)s -d 3 192.168.1.1 192.168.1.12")
69)     parser.add_argument('-d', '--delay', type=float, default=1.0, help='Delay between pings')
70)     parser.add_argument('addresses', nargs='+', help='Addresses to ping')
71)     parser_args = parser.parse_args()
72) 
73)     _results = dict()
74)     for addr in parser_args.addresses:
75)         _results[addr] = None
76)     delay = parser_args.delay
77) 
78)     _ping_queue = queue.Queue(2 * len(parser_args.addresses))  # No more than 2 pending pings per address
79)     _print_queue = queue.Queue()
80) 
81)     _logname = os.path.join(os.path.expanduser('~'), 'log', os.path.basename(sys.argv[0]).replace('py', 'txt'))
82)     _pid = os.getpid()
83) 
84)     # Choose the ping parameters appropriate for the platform
85)     if sys.platform == 'cygwin' or sys.platform == 'win32':
86)         _ping_cmd = ('ping', '-n', '1', '-w', '2000')
87)     else:
88)         _ping_cmd = ('ping', '-c', '1', '-W', '2', '-q')
89) 
90)     for i in range(len(parser_args.addresses)):
91)         t = threading.Thread(target=pinger, daemon=True)
92)         t.start()
93)         del t
94) 
95)     t = threading.Thread(target=print_manager, daemon=True)
96)     t.start()
97)     del t
98) 
99)     _print_queue.put([f'{time.strftime("%Y-%m-%d %H:%M:%S", time.localtime())}'

100)         f' PID={os.getpid()} repeat={delay}s addresses={",".join(parser_args.addresses)} Starting'])
101) 
102)     signal.signal(signal.SIGINT, log_exit)
103)     signal.signal(signal.SIGTERM, log_exit)
104)