From c5e57c0aefe71030a31234bf6e5b15aacb2ee3e8 Mon Sep 17 00:00:00 2001
From: Samuel Pilla <sp516w@att.com>
Date: Fri, 6 Apr 2018 12:49:52 -0500
Subject: [PATCH] ConfigurationSource base class

Creates and abstract base class for configuration sources
to be implemented off of.

Change-Id: I238930df61749a77b0a0aa4f033375972a159931
Blueprint: oslo-config-drivers
---
 oslo_config/sources/__init__.py | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/oslo_config/sources/__init__.py b/oslo_config/sources/__init__.py
index 0fe4454e..fb30a35a 100644
--- a/oslo_config/sources/__init__.py
+++ b/oslo_config/sources/__init__.py
@@ -40,3 +40,29 @@ class ConfigurationSourceDriver(object):
         :type group_name: str
         :returns: an instance of a subclass of ConfigurationSource
         """
+
+
+@six.add_metaclass(abc.ABCMeta)
+class ConfigurationSource(object):
+    """A configuration source option for oslo.config.
+
+    A configuration source is able to fetch configuration values based on
+    a (group, option) key from an external source that supports key-value
+    mapping such as INI files, key-value stores, secret stores, and so on.
+
+    """
+
+    @abc.abstractmethod
+    def get(self, group_name, option_name, opt):
+        """Return the value of the option from the group.
+
+        :param group_name: Name of the group.
+        :type group_name: str
+        :param option_name: Name of the option.
+        :type option_name: str
+        :param opt: The option definition.
+        :type opt: Opt
+        :returns: A tuple (value, location) where value is the option value
+                  or oslo_config.sources._NoValue if the (group, option) is
+                  not present in the source, and location is a LocationInfo.
+        """