1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
# Copyright 2015 Rackspace Hosting.
#
# Author: Eric Larson <eric.larson@rackspace.com>
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
import sys
import functools
import pkg_resources
from oslo_config import cfg
from oslo_log import log
from stevedore import hook
class HookLog(object):
"""Since logs are applied at import time, we record the log
messages for later use.
"""
LVLS = dict(
debug=log.DEBUG,
info=log.INFO,
warning=log.WARNING,
error=log.ERROR,
critical=log.CRITICAL,
exception=log.ERROR,
)
def __init__(self):
self.messages = []
def log(self, logger=None):
logger = log.getLogger(__name__)
for level, msg, args, kw in self.messages:
logger.log(level, msg, *args, **kw)
__call__ = log
def capture(self, lvl, msg, *args, **kw):
self.messages.append((lvl, msg, args, kw))
def __getattr__(self, name):
if name in self.LVLS:
return functools.partial(self.capture, self.LVLS[name])
LOG = HookLog()
def log_hook_setup():
"""Replay the log messages during the hook point initialization.
Logging isn't configured when we set up the hook points, so this
will replay the log once the config has been loaded.
"""
LOG()
class BaseHook(object):
OPTS = [
cfg.BoolOpt('disabled', default=False)
]
def __init__(self, group):
self.group = group
@property
def disabled(self):
return cfg.CONF[self.group].get('disabled', False)
def wrapper(self, *args, **kw):
return self.hook_target(*args, **kw)
def __call__(self, f):
# Save our hook target as an attribute for our wrapper method
self.hook_target = f
@functools.wraps(self.hook_target)
def wrapper(*args, **kw):
if self.disabled:
return self.hook_target(*args, **kw)
return self.hook(*args, **kw)
return wrapper
class hook_point(object):
NAMESPACE = 'designate.hook_point'
LOG_LEVEL = log.INFO
def __init__(self, name=None):
self._name = name
self.log = []
def update_config_opts(self, group, hooks):
hooks_found = False
for hook_impl in hooks:
hooks_found = True
# Add any options defined by the hook
if hasattr(hook_impl.plugin, 'OPTS'):
cfg.CONF.register_opts(hook_impl.plugin.OPTS, group=group)
if not hooks_found:
LOG.debug('No hooks found for %s', group)
else:
LOG.debug('Created hook: %s', group)
def hook_manager(self, name):
LOG.debug('Looking for hooks with: %s %s', self.NAMESPACE, name)
return hook.HookManager(self.NAMESPACE, name)
def find_name(self, func=None):
"""Derive the hook target path from the function name, unless
a name has been passed in with the constructor.
"""
if self._name:
return self._name
if not func:
return None
# derive the name from the function
self._name = '%s.%s' % (func.__module__, func.__name__)
return self._name
def init_hook(self, f):
"""Set up our hook
Try to inspect the function for a hook target path if one
wasn't passed in and set up the necessary config options.
"""
LOG.debug('Initializing hook: %s', f)
self.name = self.find_name(f)
self.group = 'hook_point:%s' % self.name
self.hooks = self.hook_manager(self.name)
self.update_config_opts(self.group, self.hooks)
def enable_hook(self, ext, f):
"""Enable the hook.
This instantiates the hook object and decorates the original
function.
"""
decorator = ext.plugin(self.group)
f = decorator(f)
f._hook_point = self # add ourselves for inspection
return f
def __call__(self, f):
# Set up all our hook information based on the function or
# hook point
self.init_hook(f)
for h in self.hooks:
f = self.enable_hook(h, f)
return f
if __name__ == '__main__':
# Use this script to find existing hook points.
hook_names = sys.argv[1:]
print('Using namespace: %s' % hook_point.NAMESPACE)
print('pkg_resources has the following entry points:')
for ep in pkg_resources.iter_entry_points(hook_point.NAMESPACE):
print(ep)
print()
print('stevedore found the following hooks:')
for name in hook_names:
for hp in hook.HookManager(hook_point.NAMESPACE, name):
print(hp)
|
