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# 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
import sys
from cloudinit.registry import DictRegistry
FINISH_EVENT_TYPE = 'finish'
START_EVENT_TYPE = 'start'
DEFAULT_CONFIG = {
'logging': {'type': 'log'},
'print': {'type': 'print'},
}
class _nameset(set):
def __getattr__(self, name):
if name in self:
return name
raise AttributeError
status = _nameset(("SUCCESS", "WARN", "FAIL"))
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, result=None):
super(FinishReportingEvent, self).__init__(
FINISH_EVENT_TYPE, name, description)
if result is None:
result = status.SUCCESS
self.result = result
if result not in status:
raise ValueError("Invalid result: %s" % result)
def as_string(self):
return '{0}: {1}: {2}: {3}'.format(
self.event_type, self.name, self.result, 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())
class StderrHandler(ReportingHandler):
def publish_event(self, event):
sys.stderr.write(event.as_string() + "\n")
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, result):
"""Report a "finish" event.
See :py:func:`.report_event` for parameter details.
"""
event = FinishReportingEvent(event_name, event_description, result)
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)
class ReportStack(object):
def __init__(self, name, description, parent=None,
reporting_enabled=None, result_on_exception=status.FAIL):
self.parent = parent
self.name = name
self.description = description
self.result_on_exception = result_on_exception
# use parents reporting value if not provided
if reporting_enabled is None:
if parent:
reporting_enabled = parent.reporting_enabled
else:
reporting_enabled = True
self.reporting_enabled = reporting_enabled
if parent:
self.fullname = '/'.join((parent.fullname, name,))
else:
self.fullname = self.name
self.children = {}
def __repr__(self):
return ("%s reporting=%s" % (self.fullname, self.reporting_enabled))
def __enter__(self):
if self.reporting_enabled:
report_start_event(self.fullname, self.description)
if self.parent:
self.parent.children[self.name] = (None, None)
return self
def childrens_finish_info(self, result=None, description=None):
for cand_result in (status.FAIL, status.WARN):
for name, (value, msg) in self.children.items():
if value == cand_result:
return (value, "[" + name + "]" + msg)
if result is None:
result = status.SUCCESS
if description is None:
description = self.description
return (result, description)
def finish_info(self, exc):
# return tuple of description, and value
if exc:
# by default, exceptions are fatal
return (self.result_on_exception, self.description)
return self.childrens_finish_info()
def __exit__(self, exc_type, exc_value, traceback):
(result, msg) = self.finish_info(exc_value)
if self.parent:
self.parent.children[self.name] = (result, msg)
if self.reporting_enabled:
report_finish_event(self.fullname, msg, result)
available_handlers.register_item('log', LogHandler)
available_handlers.register_item('print', StderrHandler)
add_configuration(DEFAULT_CONFIG)
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