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 logging
  18 import os
  19 import pkg_resources
  20
  21 from configobj import ConfigObj, flatten_errors
  22 from validate import Validator
  23
  24
  25 _log = logging.getLogger(__name__)
  26
  27
  28 CONFIG_SPEC_PATH = pkg_resources.resource_filename(
  29     'mediagoblin', 'config_spec.ini')
  30
  31
  32 def _setup_defaults(config, config_path):
  33     """
  34     Setup DEFAULTS in a config object from an (absolute) config_path.
  35     """
  36     config.setdefault('DEFAULT', {})
  37     config['DEFAULT']['here'] = os.path.dirname(config_path)
  38     config['DEFAULT']['__file__'] = config_path
  39
  40
  41 def read_mediagoblin_config(config_path, config_spec=CONFIG_SPEC_PATH):
  42     """
  43     Read a config object from config_path.
  44
  45     Does automatic value transformation based on the config_spec.
  46     Also provides %(__file__)s and %(here)s values of this file and
  47     its directory respectively similar to paste deploy.
  48
  49     Also reads for [plugins] section, appends all config_spec.ini
  50     files from said plugins into the general config_spec specification.
  51
  52     This function doesn't itself raise any exceptions if validation
  53     fails, you'll have to do something
  54
  55     Args:
  56      - config_path: path to the config file
  57      - config_spec: config file that provides defaults and value types
  58        for validation / conversion.  Defaults to mediagoblin/config_spec.ini
  59
  60     Returns:
  61       A tuple like: (config, validation_result)
  62       ... where 'conf' is the parsed config object and 'validation_result'
  63       is the information from the validation process.
  64     """
  65     config_path = os.path.abspath(config_path)
  66
  67     # PRE-READ of config file.  This allows us to fetch the plugins so
  68     # we can add their plugin specs to the general config_spec.
  69     config = ConfigObj(
  70         config_path,
  71         interpolation='ConfigParser')
  72
  73     plugins = config.get("plugins", {}).keys()
  74     plugin_configs = {}
  75
  76     for plugin in plugins:
  77         try:
  78             plugin_config_spec_path = pkg_resources.resource_filename(
  79                 plugin, "config_spec.ini")
  80             if not os.path.exists(plugin_config_spec_path):
  81                 continue
  82
  83             plugin_config_spec = ConfigObj(
  84                 plugin_config_spec_path,
  85                 encoding='UTF8', list_values=False, _inspec=True)
  86             _setup_defaults(plugin_config_spec, config_path)
  87
  88             if not "plugin_spec" in plugin_config_spec:
  89                 continue
  90
  91             plugin_configs[plugin] = plugin_config_spec["plugin_spec"]
  92
  93         except ImportError:
  94             _log.warning(
  95                 "When setting up config section, could not import '%s'" %
  96                 plugin)
  97
  98     # Now load the main config spec
  99     config_spec = ConfigObj(
 100         config_spec,
 101         encoding='UTF8', list_values=False, _inspec=True)
 102
 103     # append the plugin specific sections of the config spec
 104     config_spec['plugins'] = plugin_configs
 105
 106     _setup_defaults(config_spec, config_path)
 107
 108     config = ConfigObj(
 109         config_path,
 110         configspec=config_spec,
 111         interpolation='ConfigParser')
 112
 113     _setup_defaults(config, config_path)
 114
 115     # For now the validator just works with the default functions,
 116     # but in the future if we want to add additional validation/configuration
 117     # functions we'd add them to validator.functions here.
 118     #
 119     # See also:
 120     #   http://www.voidspace.org.uk/python/validate.html#adding-functions
 121     validator = Validator()
 122     validation_result = config.validate(validator, preserve_errors=True)
 123
 124     return config, validation_result
 125
 126
 127 REPORT_HEADER = u"""\
 128 There were validation problems loading this config file:
 129 --------------------------------------------------------
 130 """
 131
 132
 133 def generate_validation_report(config, validation_result):
 134     """
 135     Generate a report if necessary of problems while validating.
 136
 137     Returns:
 138       Either a string describing for a user the problems validating
 139       this config or None if there are no problems.
 140     """
 141     report = []
 142
 143     # Organize the report
 144     for entry in flatten_errors(config, validation_result):
 145         # each entry is a tuple
 146         section_list, key, error = entry
 147
 148         if key is not None:
 149             section_list.append(key)
 150         else:
 151             section_list.append(u'[missing section]')
 152
 153         section_string = u':'.join(section_list)
 154
 155         if error == False:
 156             # We don't care about missing values for now.
 157             continue
 158
 159         report.append(u"%s = %s" % (section_string, error))
 160
 161     if report:
 162         return REPORT_HEADER + u"\n".join(report)
 163     else:
 164         return None