chrome/test/pyautolib/chromeos/power_strip.py

   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()