PLC/Config.py

   1 #!/usr/bin/python
   2 #
   3 # PLCAPI configuration store. Supports XML-based configuration file
   4 # format exported by MyPLC.
   5 #
   6 # Mark Huang <mlhuang@cs.princeton.edu>
   7 # Copyright (C) 2004-2006 The Trustees of Princeton University
   8 #
   9 # $Id$
  10 # $URL$
  11 #
  12
  13 import os
  14 import sys
  15
  16 from PLC.Faults import *
  17 from PLC.Debug import profile
  18
  19 # If we have been checked out into a directory at the same
  20 # level as myplc, where plc_config.py lives. If we are in a
  21 # MyPLC environment, plc_config.py has already been installed
  22 # in site-packages.
  23 myplc = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))) + \
  24         os.sep + "myplc"
  25
  26 class Config:
  27     """
  28     Parse the bash/Python/PHP version of the configuration file. Very
  29     fast but no type conversions.
  30     """
  31
  32     def __init__(self, file = "/etc/planetlab/plc_config"):
  33         # Load plc_config
  34         try:
  35             execfile(file, self.__dict__)
  36         except:
  37             # Try myplc directory
  38             try:
  39                 execfile(myplc + os.sep + "plc_config", self.__dict__)
  40             except:
  41                 raise PLCAPIError("Could not find plc_config in " + \
  42                                   file + ", " + \
  43                                   myplc + os.sep + "plc_config")
  44
  45 class XMLConfig:
  46     """
  47     Parse the XML configuration file directly. Takes longer but is
  48     presumably more accurate.
  49     """
  50
  51     def __init__(self, file = "/etc/planetlab/plc_config.xml"):
  52         try:
  53             from plc_config import PLCConfiguration
  54         except:
  55             sys.path.append(myplc)
  56             from plc_config import PLCConfiguration
  57
  58         # Load plc_config.xml
  59         try:
  60             cfg = PLCConfiguration(file)
  61         except:
  62             # Try myplc directory
  63             try:
  64                 cfg = PLCConfiguration(myplc + os.sep + "plc_config.xml")
  65             except:
  66                 raise PLCAPIError("Could not find plc_config.xml in " + \
  67                                   file + ", " + \
  68                                   myplc + os.sep + "plc_config.xml")
  69
  70         for (category, variablelist) in cfg.variables().values():
  71             for variable in variablelist.values():
  72                 # Try to cast each variable to an appropriate Python
  73                 # type.
  74                 if variable['type'] == "int":
  75                     value = int(variable['value'])
  76                 elif variable['type'] == "double":
  77                     value = float(variable['value'])
  78                 elif variable['type'] == "boolean":
  79                     if variable['value'] == "true":
  80                         value = True
  81                     else:
  82                         value = False
  83                 else:
  84                     value = variable['value']
  85
  86                 # Variables are split into categories such as
  87                 # "plc_api", "plc_db", etc. Within each category are
  88                 # variables such as "host", "port", etc. For backward
  89                 # compatibility, refer to variables by their shell
  90                 # names.
  91                 shell_name = category['id'].upper() + "_" + variable['id'].upper()
  92                 setattr(self, shell_name, value)
  93
  94 if __name__ == '__main__':
  95     import pprint
  96     pprint = pprint.PrettyPrinter()
  97     pprint.pprint(Config().__dict__.items())