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