1 files changed, 37 insertions, 0 deletions
diff --git a/cloudinit/registry.py b/cloudinit/registry.py
new file mode 100644
index 00000000..04368ddf
--- /dev/null
+++ b/cloudinit/registry.py
@@ -0,0 +1,37 @@
+# Copyright 2015 Canonical Ltd.
+# This file is part of cloud-init.  See LICENCE file for license information.
+#
+# vi: ts=4 expandtab
+import copy
+
+
+class DictRegistry(object):
+    """A simple registry for a mapping of objects."""
+
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self._items = {}
+
+    def register_item(self, key, item):
+        """Add item to the registry."""
+        if key in self._items:
+            raise ValueError(
+                'Item already registered with key {0}'.format(key))
+        self._items[key] = item
+
+    def unregister_item(self, key, force=True):
+        """Remove item from the registry."""
+        if key in self._items:
+            del self._items[key]
+        elif not force:
+            raise KeyError("%s: key not present to unregister" % key)
+
+    @property
+    def registered_items(self):
+        """All the items that have been registered.
+
+        This cannot be used to modify the contents of the registry.
+        """
+        return copy.copy(self._items)