0e17f4ca42
The hook points are applied prior to any logging configuration. This makes it difficult for a hook author to ensure that the correct configuration and package entry points have been added. This patch takes the log messages and buffers them for replay after the logging has been configure. The replay function is then called in each of the commands after the configuration has been read. Closes-Bug: #1465731 Change-Id: Ia5cc2dba53056c55017b3a104a1f4e22e6594ae0
184 lines
5.1 KiB
Python
184 lines
5.1 KiB
Python
# Copyright 2015 Rackspace Hosting.
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#
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# Author: Eric Larson <eric.larson@rackspace.com>
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import sys
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import functools
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import logging as logmodule
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import pkg_resources
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from oslo_config import cfg
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from oslo_log import log as logging
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from stevedore import hook
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class HookLog(object):
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"""Since logs are applied at import time, we record the log
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messages for later use.
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"""
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LVLS = dict(
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debug=logmodule.DEBUG,
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info=logmodule.INFO,
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warning=logmodule.WARNING,
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error=logmodule.ERROR,
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critical=logmodule.CRITICAL,
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exception=logmodule.ERROR,
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)
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def __init__(self):
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self.messages = []
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def log(self, logger=None):
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logger = logging.getLogger(__name__)
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for level, msg, args, kw in self.messages:
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logger.log(level, msg, *args, **kw)
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__call__ = log
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def capture(self, lvl, msg, *args, **kw):
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self.messages.append((lvl, msg, args, kw))
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def __getattr__(self, name):
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if name in self.LVLS:
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return functools.partial(self.capture, self.LVLS[name])
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LOG = HookLog()
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def log_hook_setup():
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"""Replay the log messages during the hook point initialization.
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Logging isn't configured when we set up the hook points, so this
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will replay the log once the config has been loaded.
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"""
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LOG()
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class BaseHook(object):
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OPTS = [
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cfg.BoolOpt('disabled', default=False)
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]
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def __init__(self, group):
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self.group = group
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@property
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def disabled(self):
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return cfg.CONF[self.group].get('disabled', False)
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def wrapper(self, *args, **kw):
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return self.hook_target(*args, **kw)
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def __call__(self, f):
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# Save our hook target as an attribute for our wrapper method
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self.hook_target = f
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@functools.wraps(self.hook_target)
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def wrapper(*args, **kw):
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if self.disabled:
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return self.hook_target(*args, **kw)
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return self.hook(*args, **kw)
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return wrapper
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class hook_point(object):
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NAMESPACE = 'designate.hook_point'
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LOG_LEVEL = logmodule.INFO
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def __init__(self, name=None):
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self._name = name
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self.log = []
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def update_config_opts(self, group, hooks):
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hooks_found = False
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for hook_impl in hooks:
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hooks_found = True
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# Add any options defined by the hook
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if hasattr(hook_impl.plugin, 'OPTS'):
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cfg.CONF.register_opts(hook_impl.plugin.OPTS, group=group)
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if not hooks_found:
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LOG.debug('No hooks found for %s', group)
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else:
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LOG.debug('Created hook: %s', group)
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def hook_manager(self, name):
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LOG.debug('Looking for hooks with: %s %s', self.NAMESPACE, name)
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return hook.HookManager(self.NAMESPACE, name)
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def find_name(self, func=None):
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"""Derive the hook target path from the function name, unless
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a name has been passed in with the constuctor.
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"""
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if self._name:
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return self._name
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if not func:
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return None
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# derive the name from the function
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self._name = '%s.%s' % (func.__module__, func.__name__)
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return self._name
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def init_hook(self, f):
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"""Set up our hook
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Try to inspect the function for a hook target path if one
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wasn't passed in and set up the necessary config options.
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"""
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LOG.debug('Initializing hook: %s', f)
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self.name = self.find_name(f)
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self.group = 'hook_point:%s' % self.name
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self.hooks = self.hook_manager(self.name)
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self.update_config_opts(self.group, self.hooks)
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def enable_hook(self, ext, f):
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"""Enable the hook.
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This instantiates the hook object and decorates the original
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function.
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"""
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decorator = ext.plugin(self.group)
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f = decorator(f)
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f._hook_point = self # add ourselves for inspection
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return f
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def __call__(self, f):
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# Set up all our hook information based on the function or
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# hook point
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self.init_hook(f)
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for h in self.hooks:
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f = self.enable_hook(h, f)
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return f
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if __name__ == '__main__':
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# Use this script to find existing hook points.
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hook_names = sys.argv[1:]
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print('Using namespace: %s' % hook_point.NAMESPACE)
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print('pkg_resources has the following entry points:')
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for ep in pkg_resources.iter_entry_points(hook_point.NAMESPACE):
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print(ep)
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print()
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print('stevedore found the following hooks:')
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for name in hook_names:
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for hp in hook.HookManager(hook_point.NAMESPACE, name):
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print(hp)
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