1 # Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 import logging 6 import re 7 import telnetlib 8 9 10 class PowerStrip(object): 11 """Controls Server Technology CW-16V1-C20M switched CDUs. 12 (Cabinet Power Distribution Unit) 13 14 This class is used to control the CW-16V1-C20M unit which 15 is a 16 port remote power strip. The strip supports AC devices 16 using 100-120V 50/60Hz input voltages. The commands in this 17 class are supported by switches that use Sentry Switched CDU Version 6.0g. 18 19 Opens a new connection for every command. 20 """ 21 22 TIMEOUT = 10 23 24 def __init__(self, host, user='admn', password='admn'): 25 self._host = host 26 self._user = user 27 self._password = password 28 29 def PowerOff(self, outlet): 30 """Powers off the device that is plugged into the specified outlet. 31 32 Args: 33 outlet: The outlet ID defined on the switch (eg. .a14). 34 """ 35 self._DoCommand('off', outlet) 36 37 def PowerOn(self, outlet): 38 """Powers on the device that is plugged into the specified outlet. 39 40 Args: 41 outlet: The outlet ID defined on the switch (eg. .a14). 42 """ 43 self._DoCommand('on', outlet) 44 45 def _DoCommand(self, command, outlet): 46 """Performs power strip commands on the specified outlet. 47 48 Sample telnet interaction: 49 Escape character is '^]'. 50 51 Sentry Switched CDU Version 6.0g 52 53 Username: admn 54 Password: < password hidden from view > 55 56 Location: 57 58 Switched CDU: on .a1 59 60 Outlet Outlet Outlet Control 61 ID Name Status State 62 63 .A1 TowerA_Outlet1 On On 64 65 Command successful 66 67 Switched CDU: < cdu cmd > 68 69 Args: 70 command: A valid CW-16V1-C20M command that follows the format 71 <command> <outlet>. 72 outlet: The outlet ID defined on the switch (eg. .a14). 73 """ 74 tn = telnetlib.Telnet() 75 # To avoid 'Connection Reset by Peer: 104' exceptions when rapid calls 76 # are made to the telnet server on the power strip, we retry executing 77 # a command. 78 retry = range(5) 79 for attempt in retry: 80 try: 81 tn.open(self._host, timeout=PowerStrip.TIMEOUT) 82 resp = tn.read_until('Username:', timeout=PowerStrip.TIMEOUT) 83 assert 'Username' in resp, 'Username not found in response. (%s)' % resp 84 tn.write(self._user + '\n') 85 86 resp = tn.read_until('Password:', timeout=PowerStrip.TIMEOUT) 87 assert 'Password' in resp, 'Password not found in response. (%s)' % resp 88 tn.write(self._password + '\n') 89 90 resp = tn.read_until('Switched CDU:', timeout=PowerStrip.TIMEOUT) 91 assert 'Switched CDU' in resp, 'Standard prompt not found in ' \ 92 'response. (%s)' % resp 93 tn.write('%s %s\n' % (command, outlet)) 94 95 # Obtain the output of command and make sure it matches with the action 96 # we performed. 97 # Sample valid output: 98 # .A1 TowerA_Outlet1 On On 99 resp = tn.read_until('Switched CDU:', timeout=PowerStrip.TIMEOUT) 100 if not re.search('%s\s+\S+\s+%s\s+%s' % (outlet, command, command), 101 resp, re.I): 102 raise Exception('Command \'%s\' execution failed. (%s)' % 103 (command, resp)) 104 105 # Exiting the telnet session cleanly significantly reduces the chance of 106 # connection error on initiating the following telnet session. 107 tn.write('exit\n') 108 tn.read_all() 109 110 # If we've gotten this far, there is no need to retry. 111 break 112 except Exception as e: 113 logging.debug('Power strip retry on cmd "%s". Reason: %s' 114 % (command, str(e))) 115 if attempt == retry[-1]: 116 raise Exception('Sentry Command "%s" failed. ' 117 'Reason: %s' % (command, str(e))) 118 finally: 119 tn.close() 120
