pull from 2.0 trunk @ a433358bbcf4e8a771b80cae34468409ed5a811d

2 files changed, 145 insertions, 0 deletions

diff --git a/cloudinit/registry.py b/cloudinit/registry.py
new file mode 100644
index 00000000..46cf0585
--- /dev/null
+++ b/cloudinit/registry.py
@@ -0,0 +1,23 @@
+import copy
+
+
+class DictRegistry(object):
+    """A simple registry for a mapping of objects."""
+
+    def __init__(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
+
+    @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)
diff --git a/cloudinit/reporting.py b/cloudinit/reporting.py
new file mode 100644
index 00000000..d2dd4fec
--- /dev/null
+++ b/cloudinit/reporting.py
@@ -0,0 +1,122 @@
+# Copyright 2015 Canonical Ltd.
+# This file is part of cloud-init.  See LICENCE file for license information.
+#
+# vi: ts=4 expandtab
+"""
+cloud-init reporting framework
+
+The reporting framework is intended to allow all parts of cloud-init to
+report events in a structured manner.
+"""
+
+import abc
+import logging
+
+from cloudinit.registry import DictRegistry
+
+
+FINISH_EVENT_TYPE = 'finish'
+START_EVENT_TYPE = 'start'
+
+DEFAULT_CONFIG = {
+    'logging': {'type': 'log'},
+}
+
+
+instantiated_handler_registry = DictRegistry()
+available_handlers = DictRegistry()
+
+
+class ReportingEvent(object):
+    """Encapsulation of event formatting."""
+
+    def __init__(self, event_type, name, description):
+        self.event_type = event_type
+        self.name = name
+        self.description = description
+
+    def as_string(self):
+        """The event represented as a string."""
+        return '{0}: {1}: {2}'.format(
+            self.event_type, self.name, self.description)
+
+
+class FinishReportingEvent(ReportingEvent):
+
+    def __init__(self, name, description, successful=None):
+        super(FinishReportingEvent, self).__init__(
+            FINISH_EVENT_TYPE, name, description)
+        self.successful = successful
+
+    def as_string(self):
+        if self.successful is None:
+            return super(FinishReportingEvent, self).as_string()
+        success_string = 'success' if self.successful else 'fail'
+        return '{0}: {1}: {2}: {3}'.format(
+            self.event_type, self.name, success_string, self.description)
+
+
+class ReportingHandler(object):
+
+    @abc.abstractmethod
+    def publish_event(self, event):
+        raise NotImplementedError
+
+
+class LogHandler(ReportingHandler):
+    """Publishes events to the cloud-init log at the ``INFO`` log level."""
+
+    def publish_event(self, event):
+        """Publish an event to the ``INFO`` log level."""
+        logger = logging.getLogger(
+            '.'.join([__name__, event.event_type, event.name]))
+        logger.info(event.as_string())
+
+
+def add_configuration(config):
+    for handler_name, handler_config in config.items():
+        handler_config = handler_config.copy()
+        cls = available_handlers.registered_items[handler_config.pop('type')]
+        instance = cls(**handler_config)
+        instantiated_handler_registry.register_item(handler_name, instance)
+
+
+def report_event(event):
+    """Report an event to all registered event handlers.
+
+    This should generally be called via one of the other functions in
+    the reporting module.
+
+    :param event_type:
+        The type of the event; this should be a constant from the
+        reporting module.
+    """
+    for _, handler in instantiated_handler_registry.registered_items.items():
+        handler.publish_event(event)
+
+
+def report_finish_event(event_name, event_description, successful=None):
+    """Report a "finish" event.
+
+    See :py:func:`.report_event` for parameter details.
+    """
+    event = FinishReportingEvent(event_name, event_description, successful)
+    return report_event(event)
+
+
+def report_start_event(event_name, event_description):
+    """Report a "start" event.
+
+    :param event_name:
+        The name of the event; this should be a topic which events would
+        share (e.g. it will be the same for start and finish events).
+
+    :param event_description:
+        A human-readable description of the event that has occurred.
+    """
+    event = ReportingEvent(START_EVENT_TYPE, event_name, event_description)
+    return report_event(event)
+
+
+available_handlers.register_item('log', LogHandler)
+add_configuration(DEFAULT_CONFIG)