osm_policy_module/core/config.py

   1 # -*- coding: utf-8 -*-
   2
   3 # Copyright 2018 Whitestack, LLC
   4 # *************************************************************
   5
   6 # This file is part of OSM Monitoring module
   7 # All Rights Reserved to Whitestack, LLC
   8
   9 # Licensed under the Apache License, Version 2.0 (the "License"); you may
  10 # not use this file except in compliance with the License. You may obtain
  11 # a copy of the License at
  12
  13 #         http://www.apache.org/licenses/LICENSE-2.0
  14
  15 # Unless required by applicable law or agreed to in writing, software
  16 # distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  17 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  18 # License for the specific language governing permissions and limitations
  19 # under the License.
  20
  21 # For those usages not covered by the Apache License, Version 2.0 please
  22 # contact: bdiaz@whitestack.com or glavado@whitestack.com
  23 ##
  24 """Global configuration managed by environment variables."""
  25
  26 import logging
  27 import os
  28
  29 from collections import namedtuple
  30
  31 import six
  32
  33 from osm_policy_module.core.singleton import Singleton
  34
  35 log = logging.getLogger(__name__)
  36
  37
  38 class BadConfigError(Exception):
  39     """Configuration exception."""
  40
  41     pass
  42
  43
  44 class CfgParam(namedtuple('CfgParam', ['key', 'default', 'data_type'])):
  45     """Configuration parameter definition."""
  46
  47     def value(self, data):
  48         """Convert a string to the parameter type."""
  49         try:
  50             return self.data_type(data)
  51         except (ValueError, TypeError):
  52             raise BadConfigError(
  53                 'Invalid value "%s" for configuration parameter "%s"' % (
  54                     data, self.key))
  55
  56
  57 @Singleton
  58 class Config(object):
  59     """Configuration object."""
  60
  61     _configuration = [
  62         CfgParam('OSMPOL_MESSAGE_DRIVER', "kafka", six.text_type),
  63         CfgParam('OSMPOL_MESSAGE_HOST', "localhost", six.text_type),
  64         CfgParam('OSMPOL_MESSAGE_PORT', 9092, int),
  65         CfgParam('OSMPOL_DATABASE_DRIVER', "mongo", six.text_type),
  66         CfgParam('OSMPOL_DATABASE_HOST', "mongo", six.text_type),
  67         CfgParam('OSMPOL_DATABASE_PORT', 27017, int),
  68         CfgParam('OSMPOL_SQL_DATABASE_URI', "sqlite:///policy_module.db", six.text_type),
  69         CfgParam('OSMPOL_LOG_LEVEL', "INFO", six.text_type),
  70         CfgParam('OSMPOL_KAFKA_LOG_LEVEL', "WARN", six.text_type),
  71     ]
  72
  73     _config_dict = {cfg.key: cfg for cfg in _configuration}
  74     _config_keys = _config_dict.keys()
  75
  76     def __init__(self):
  77         """Set the default values."""
  78         for cfg in self._configuration:
  79             setattr(self, cfg.key, cfg.default)
  80         self.read_environ()
  81
  82     def read_environ(self):
  83         """Check the appropriate environment variables and update defaults."""
  84         for key in self._config_keys:
  85             try:
  86                 val = self._config_dict[key].data_type(os.environ[key])
  87                 setattr(self, key, val)
  88             except KeyError as exc:
  89                 log.debug("Environment variable not present: %s", exc)
  90         return