mediagoblin/init/config.py

   1 # GNU MediaGoblin -- federated, autonomous media hosting
   2 # Copyright (C) 2011, 2012 MediaGoblin contributors.  See AUTHORS.
   3 #
   4 # This program is free software: you can redistribute it and/or modify
   5 # it under the terms of the GNU Affero General Public License as published by
   6 # the Free Software Foundation, either version 3 of the License, or
   7 # (at your option) any later version.
   8 #
   9 # This program is distributed in the hope that it will be useful,
  10 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 # GNU Affero General Public License for more details.
  13 #
  14 # You should have received a copy of the GNU Affero General Public License
  15 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 import os
  18 import pkg_resources
  19
  20 from configobj import ConfigObj, flatten_errors
  21 from validate import Validator
  22
  23
  24 CONFIG_SPEC_PATH = pkg_resources.resource_filename(
  25     'mediagoblin', 'config_spec.ini')
  26
  27
  28 def _setup_defaults(config, config_path):
  29     """
  30     Setup DEFAULTS in a config object from an (absolute) config_path.
  31     """
  32     config.setdefault('DEFAULT', {})
  33     config['DEFAULT']['here'] = os.path.dirname(config_path)
  34     config['DEFAULT']['__file__'] = config_path
  35
  36
  37 def read_mediagoblin_config(config_path, config_spec=CONFIG_SPEC_PATH):
  38     """
  39     Read a config object from config_path.
  40
  41     Does automatic value transformation based on the config_spec.
  42     Also provides %(__file__)s and %(here)s values of this file and
  43     its directory respectively similar to paste deploy.
  44
  45     This function doesn't itself raise any exceptions if validation
  46     fails, you'll have to do something
  47
  48     Args:
  49      - config_path: path to the config file
  50      - config_spec: config file that provides defaults and value types
  51        for validation / conversion.  Defaults to mediagoblin/config_spec.ini
  52
  53     Returns:
  54       A tuple like: (config, validation_result)
  55       ... where 'conf' is the parsed config object and 'validation_result'
  56       is the information from the validation process.
  57     """
  58     config_path = os.path.abspath(config_path)
  59
  60     config_spec = ConfigObj(
  61         config_spec,
  62         encoding='UTF8', list_values=False, _inspec=True)
  63
  64     _setup_defaults(config_spec, config_path)
  65
  66     config = ConfigObj(
  67         config_path,
  68         configspec=config_spec,
  69         interpolation='ConfigParser')
  70
  71     _setup_defaults(config, config_path)
  72
  73     # For now the validator just works with the default functions,
  74     # but in the future if we want to add additional validation/configuration
  75     # functions we'd add them to validator.functions here.
  76     #
  77     # See also:
  78     #   http://www.voidspace.org.uk/python/validate.html#adding-functions
  79     validator = Validator()
  80     validation_result = config.validate(validator, preserve_errors=True)
  81
  82     return config, validation_result
  83
  84
  85 REPORT_HEADER = u"""\
  86 There were validation problems loading this config file:
  87 --------------------------------------------------------
  88 """
  89
  90
  91 def generate_validation_report(config, validation_result):
  92     """
  93     Generate a report if necessary of problems while validating.
  94
  95     Returns:
  96       Either a string describing for a user the problems validating
  97       this config or None if there are no problems.
  98     """
  99     report = []
 100
 101     # Organize the report
 102     for entry in flatten_errors(config, validation_result):
 103         # each entry is a tuple
 104         section_list, key, error = entry
 105
 106         if key is not None:
 107             section_list.append(key)
 108         else:
 109             section_list.append(u'[missing section]')
 110
 111         section_string = u':'.join(section_list)
 112
 113         if error == False:
 114             # We don't care about missing values for now.
 115             continue
 116
 117         report.append(u"%s = %s" % (section_string, error))
 118
 119     if report:
 120         return REPORT_HEADER + u"\n".join(report)
 121     else:
 122         return None