Migrates POL code from MON repo

[osm/POL.git] / osm_policy_module / core / config.py

diff --git a/osm_policy_module/core/config.py b/osm_policy_module/core/config.py
new file mode 100644 (file)
index 0000000..dab409b
--- /dev/null
+++ b/osm_policy_module/core/config.py
@@ -0,0 +1,89 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2018 Whitestack, LLC
+# *************************************************************
+
+# This file is part of OSM Monitoring module
+# All Rights Reserved to Whitestack, LLC
+
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+
+#         http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+# For those usages not covered by the Apache License, Version 2.0 please
+# contact: bdiaz@whitestack.com or glavado@whitestack.com
+##
+"""Global configuration managed by environment variables."""
+
+import logging
+import os
+
+from collections import namedtuple
+
+import six
+
+from osm_policy_module.core.singleton import Singleton
+
+log = logging.getLogger(__name__)
+
+
+class BadConfigError(Exception):
+    """Configuration exception."""
+
+    pass
+
+
+class CfgParam(namedtuple('CfgParam', ['key', 'default', 'data_type'])):
+    """Configuration parameter definition."""
+
+    def value(self, data):
+        """Convert a string to the parameter type."""
+        try:
+            return self.data_type(data)
+        except (ValueError, TypeError):
+            raise BadConfigError(
+                'Invalid value "%s" for configuration parameter "%s"' % (
+                    data, self.key))
+
+
+@Singleton
+class Config(object):
+    """Configuration object."""
+
+    _configuration = [
+        CfgParam('OSMPOL_MESSAGE_DRIVER', "kafka", six.text_type),
+        CfgParam('OSMPOL_MESSAGE_HOST', "localhost", six.text_type),
+        CfgParam('OSMPOL_MESSAGE_PORT', 9092, int),
+        CfgParam('OSMPOL_DATABASE_DRIVER', "mongo", six.text_type),
+        CfgParam('OSMPOL_DATABASE_HOST', "mongo", six.text_type),
+        CfgParam('OSMPOL_DATABASE_PORT', 27017, int),
+        CfgParam('OSMPOL_SQL_DATABASE_URI', "sqlite:///mon_sqlite.db", six.text_type),
+        CfgParam('OSMPOL_LOG_LEVEL', "INFO", six.text_type),
+    ]
+
+    _config_dict = {cfg.key: cfg for cfg in _configuration}
+    _config_keys = _config_dict.keys()
+
+    def __init__(self):
+        """Set the default values."""
+        for cfg in self._configuration:
+            setattr(self, cfg.key, cfg.default)
+        self.read_environ()
+
+    def read_environ(self):
+        """Check the appropriate environment variables and update defaults."""
+        for key in self._config_keys:
+            try:
+                val = self._config_dict[key].data_type(os.environ[key])
+                setattr(self, key, val)
+            except KeyError as exc:
+                log.debug("Environment variable not present: %s", exc)
+        return