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 copy
  18 import logging
  19 import os
  20 import pkg_resources
  21
  22 from configobj import ConfigObj, flatten_errors
  23 from validate import Validator
  24
  25
  26 _log = logging.getLogger(__name__)
  27
  28
  29 CONFIG_SPEC_PATH = pkg_resources.resource_filename(
  30     'mediagoblin', 'config_spec.ini')
  31
  32
  33 def _setup_defaults(config, config_path, extra_defaults=None):
  34     """
  35     Setup DEFAULTS in a config object from an (absolute) config_path.
  36     """
  37     extra_defaults = extra_defaults or {}
  38
  39     config.setdefault('DEFAULT', {})
  40     config['DEFAULT']['here'] = os.path.dirname(config_path)
  41     config['DEFAULT']['__file__'] = config_path
  42
  43     for key, value in extra_defaults.items():
  44         config['DEFAULT'].setdefault(key, value)
  45
  46
  47 def read_mediagoblin_config(config_path, config_spec_path=CONFIG_SPEC_PATH):
  48     """
  49     Read a config object from config_path.
  50
  51     Does automatic value transformation based on the config_spec.
  52     Also provides %(__file__)s and %(here)s values of this file and
  53     its directory respectively similar to paste deploy.
  54
  55     Also reads for [plugins] section, appends all config_spec.ini
  56     files from said plugins into the general config_spec specification.
  57
  58     This function doesn't itself raise any exceptions if validation
  59     fails, you'll have to do something
  60
  61     Args:
  62      - config_path: path to the config file
  63      - config_spec_path: config file that provides defaults and value types
  64        for validation / conversion.  Defaults to mediagoblin/config_spec.ini
  65
  66     Returns:
  67       A tuple like: (config, validation_result)
  68       ... where 'conf' is the parsed config object and 'validation_result'
  69       is the information from the validation process.
  70     """
  71     config_path = os.path.abspath(config_path)
  72
  73     # PRE-READ of config file.  This allows us to fetch the plugins so
  74     # we can add their plugin specs to the general config_spec.
  75     config = ConfigObj(
  76         config_path,
  77         interpolation="ConfigParser")
  78
  79     # temporary bootstrap, just setup here and __file__... we'll do this again
  80     _setup_defaults(config, config_path)
  81
  82     # Now load the main config spec
  83     config_spec = ConfigObj(
  84         config_spec_path,
  85         encoding="UTF8", list_values=False, _inspec=True)
  86
  87     # HACK to get MediaGoblin running under Docker/Python 3. Without this line,
  88     # `./bin/gmg dbupdate` fails as the configuration under 'DEFAULT' in
  89     # config_spec still had %(here)s markers in it, when these should have been
  90     # replaced with actual paths, resulting in
  91     # "configobj.MissingInterpolationOption: missing option "here" in
  92     # interpolation". This issue doesn't seem to appear when running on Guix,
  93     # but adding this line also doesn't appear to cause problems on Guix.
  94     _setup_defaults(config_spec, config_path)
  95
  96     # Set up extra defaults that will be pushed into the rest of the
  97     # configs.  This is a combined extrapolation of defaults based on
  98     mainconfig_defaults = copy.copy(config_spec.get("DEFAULT", {}))
  99     mainconfig_defaults.update(config["DEFAULT"])
 100
 101     plugins = config.get("plugins", {}).keys()
 102     plugin_configs = {}
 103
 104     for plugin in plugins:
 105         try:
 106             plugin_config_spec_path = pkg_resources.resource_filename(
 107                 plugin, "config_spec.ini")
 108             if not os.path.exists(plugin_config_spec_path):
 109                 continue
 110
 111             plugin_config_spec = ConfigObj(
 112                 plugin_config_spec_path,
 113                 encoding="UTF8", list_values=False, _inspec=True)
 114             _setup_defaults(
 115                 plugin_config_spec, config_path, mainconfig_defaults)
 116
 117             if not "plugin_spec" in plugin_config_spec:
 118                 continue
 119
 120             plugin_configs[plugin] = plugin_config_spec["plugin_spec"]
 121
 122         except ImportError:
 123             _log.warning(
 124                 "When setting up config section, could not import '%s'" %
 125                 plugin)
 126
 127     # append the plugin specific sections of the config spec
 128     config_spec["plugins"] = plugin_configs
 129
 130     _setup_defaults(config_spec, config_path, mainconfig_defaults)
 131
 132     config = ConfigObj(
 133         config_path,
 134         configspec=config_spec,
 135         encoding="UTF8",
 136         interpolation="ConfigParser")
 137
 138     _setup_defaults(config, config_path, mainconfig_defaults)
 139
 140     # For now the validator just works with the default functions,
 141     # but in the future if we want to add additional validation/configuration
 142     # functions we'd add them to validator.functions here.
 143     #
 144     # See also:
 145     #   http://www.voidspace.org.uk/python/validate.html#adding-functions
 146     validator = Validator()
 147     validation_result = config.validate(validator, preserve_errors=True)
 148
 149     return config, validation_result
 150
 151
 152 REPORT_HEADER = u"""\
 153 There were validation problems loading this config file:
 154 --------------------------------------------------------
 155 """
 156
 157
 158 def generate_validation_report(config, validation_result):
 159     """
 160     Generate a report if necessary of problems while validating.
 161
 162     Returns:
 163       Either a string describing for a user the problems validating
 164       this config or None if there are no problems.
 165     """
 166     report = []
 167
 168     # Organize the report
 169     for entry in flatten_errors(config, validation_result):
 170         # each entry is a tuple
 171         section_list, key, error = entry
 172
 173         if key is not None:
 174             section_list.append(key)
 175         else:
 176             section_list.append(u'[missing section]')
 177
 178         section_string = u':'.join(section_list)
 179
 180         if error == False:
 181             # We don't care about missing values for now.
 182             continue
 183
 184         report.append(u"%s = %s" % (section_string, error))
 185
 186     if report:
 187         return REPORT_HEADER + u"\n".join(report)
 188     else:
 189         return None