monitoring-scripts/check_minecraft

#!/usr/bin/env python2
# coding=utf8

from datetime import datetime, timedelta
import sys, string, socket, time, argparse

# Exit statuses recognized by Nagios.
STATE_OK = 0
STATE_WARNING = 1
STATE_CRITICAL = 2
STATE_UNKNOWN = 3

# Output formatting string.
OUTPUT_OK = "MINECRAFT OK: {0} - {1} bytes in {2:.3} second response time|time={2}s;{3};{4};0.0;{5}"
OUTPUT_WARNING = "MINECRAFT WARNING: {0} - {1} bytes in {2:.3} second response time|time={2}s;{3};{4};0.0;{5}"
OUTPUT_CRITICAL = "MINECRAFT CRITICAL: {0} - {1} bytes in {2:.3} second response time|time={2}s;{3};{4};0.0;{5}"
OUTPUT_EXCEPTION = "MINECRAFT CRITICAL: {0}"
OUTPUT_UNKNOWN = "MINECRAFT UNKNOWN: Invalid arguments"

# Minecraft packet ID:s, delimiters and encoding.
MC_SERVER_LIST_PING = "\xfe"
MC_DISCONNECT = "\xff"
MC_DELIMITER = u"\xa7"
MC_ENCODING = "utf-16be"

def log(start, message):
	print("{0}: {1}".format(datetime.now() - start, message))

def get_server_info(host, port, num_checks, timeout, verbose):
	start_time = datetime.now()
	total_delta = timedelta()
	byte_count = len(MC_SERVER_LIST_PING) * num_checks

	# Contact the server multiple times to get a stable average response time.
	for i in range(0, num_checks):
		if (verbose): iteration = "Iteration {0}/{1}: ".format(i + 1, num_checks)

		# Save start time and connect to server.
		if (verbose): log(start_time, "{0}Connecting to {1} on port {2}.".format(iteration, host, port))
		net_start_time = datetime.now()
		s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		s.settimeout(timeout)
		s.connect((host, port))

		# Send Minecraft Server List Ping packet.
		if (verbose): log(start_time, "{0}Sending Server List Ping.".format(iteration))
		s.send(MC_SERVER_LIST_PING)

		# Receive answer from server. The largest answer returned by the server that also works with the Minecraft client
		# seems to be around 520 bytes (259 unicode character at 2 bytes each plus one start byte and one length byte).
		if (verbose): log(start_time, "{0}Receiving data...".format(iteration))
		data = s.recv(550)
		data_len = len(data)
		byte_count += data_len
		if (verbose): log(start_time, "{0}Received {1} bytes".format(iteration, data_len))

		s.close()

		# Check if returned data seems valid. If not, throw AssertionError exception.
		if (verbose):
			if (data[0] == MC_DISCONNECT):
				log(start_time, "Returned data seems valid.")
			else:
				log(start_time, "Returned data is invalid. First byte is {0:#x}.".format(ord(data[0])))

		assert data[0] == MC_DISCONNECT

		# Save response time for later average calculation.
		delta = datetime.now() - net_start_time
		total_delta += delta

		time.sleep(0.1)

	# Calculate the average response time in seconds
	total_response = total_delta.seconds + total_delta.microseconds / 1000000.0
	average_response = total_response / num_checks

	# Decode and split returned skipping the first two bytes.
	info = data[3:].decode(MC_ENCODING).split(MC_DELIMITER)
	motd = info[:]
	del motd[-1] # removing max_players
	del motd[-1] # removing players
	motd = ''.join(motd).replace("\n","") # removing newlines

	return {'motd': motd,
			'players': int(info[-2]),
			'max_players': int(info[-1]),
			'byte_count': byte_count,
			'response_time': average_response}

def main():
	parser = argparse.ArgumentParser(description="This plugin will try to connect to a Minecraft server.");

	parser.add_argument('-H', '--hostname', dest='hostname', metavar='ADDRESS', required=True, help="host name or IP address")
	parser.add_argument('-p', '--port', dest='port', type=int, default=25565, metavar='INTEGER', help="port number (default: 25565)")
	parser.add_argument('-n', '--number-of-checks', dest='num_checks', type=int, default=5, metavar='INTEGER', help="number of checks to get stable average response time (default: 5)")
	parser.add_argument('-m', '--motd', dest='motd', default='A Minecraft Server', metavar='STRING', help="expected motd in server response (default: A Minecraft Server)")
	parser.add_argument('-f', '--warn-on-full', dest='full', action='store_true', help="generate warning if server is full")
	parser.add_argument('-w', '--warning', dest='warning', type=float, default=0.0, metavar='DOUBLE', help="response time to result in warning status (seconds)")
	parser.add_argument('-c', '--critical', dest='critical', type=float, default=0.0, metavar='DOUBLE', help="response time to result in critical status (seconds)")
	parser.add_argument('-t', '--timeout', dest='timeout', type=float, default=10.0, metavar='DOUBLE', help="seconds before connection times out (default: 10)")
	parser.add_argument('-v', '--verbose', dest='verbose', action='store_true', help="show details for command-line debugging (Nagios may truncate output)")

	# Parse the arguments. If it failes, exit overriding exit code.
	try:
		args = parser.parse_args()
	except SystemExit:
		print(OUTPUT_UNKNOWN)
		sys.exit(STATE_UNKNOWN)

	try:
		info = get_server_info(args.hostname, args.port, args.num_checks, args.timeout, args.verbose)

		if string.find(info['motd'], args.motd) > -1:
			# Check if response time is above critical level.
			if args.critical and info['response_time'] > args.critical:
				print(OUTPUT_CRITICAL.format("{0} second response time".format(info['response_time']), info['byte_count'], info['response_time'], args.warning, args.critical, args.timeout))
				sys.exit(STATE_CRITICAL)

			# Check if response time is above warning level.
			if args.warning and info['response_time'] > args.warning:
				print(OUTPUT_WARNING.format("{0} second response time".format(info['response_time']), info['byte_count'], info['response_time'], args.warning, args.critical, args.timeout))
				sys.exit(STATE_WARNING)

			# Check if server is full.
			if args.full and info['players'] == info['max_players']:
				print(OUTPUT_WARNING.format("Server full! {0} players online".format(info['players']), info['byte_count'], info['response_time'], args.warning, args.critical, args.timeout))
				sys.exit(STATE_WARNING)

			print(OUTPUT_OK.format("{0}/{1} players online".format(info['players'], info['max_players']), info['byte_count'], info['response_time'], args.warning, args.critical, args.timeout))
			sys.exit(STATE_OK)

		else:
			print(OUTPUT_WARNING.format("Unexpected MOTD, {0}".format(info['motd']), info['byte_count'], info['response_time'], args.warning, args.critical, args.timeout))
			sys.exit(STATE_WARNING)

	except socket.error as msg:
		print(OUTPUT_EXCEPTION.format(msg))
		sys.exit(STATE_CRITICAL)

	except AssertionError:
		print(OUTPUT_EXCEPTION.format("Invalid data returned by server"))
		sys.exit(STATE_CRITICAL)

	except UnicodeDecodeError:
		print(OUTPUT_EXCEPTION.format("Unable to decode server response"))
		sys.exit(STATE_CRITICAL)

if __name__ == "__main__":
	main()