deb-ceilometer/ceilometer/declarative.py

176 lines
6.3 KiB
Python

#
# 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 os
from jsonpath_rw_ext import parser
from oslo_config import cfg
from oslo_log import log
import six
import yaml
from ceilometer.i18n import _, _LI
LOG = log.getLogger(__name__)
class DefinitionException(Exception):
def __init__(self, message, definition_cfg):
super(DefinitionException, self).__init__(message)
self.definition_cfg = definition_cfg
class Definition(object):
JSONPATH_RW_PARSER = parser.ExtentedJsonPathParser()
GETTERS_CACHE = {}
def __init__(self, name, cfg, plugin_manager):
self.cfg = cfg
self.name = name
self.plugin = None
if isinstance(cfg, dict):
if 'fields' not in cfg:
raise DefinitionException(
_("The field 'fields' is required for %s") % name,
self.cfg)
if 'plugin' in cfg:
plugin_cfg = cfg['plugin']
if isinstance(plugin_cfg, six.string_types):
plugin_name = plugin_cfg
plugin_params = {}
else:
try:
plugin_name = plugin_cfg['name']
except KeyError:
raise DefinitionException(
_('Plugin specified, but no plugin name supplied '
'for %s') % name, self.cfg)
plugin_params = plugin_cfg.get('parameters')
if plugin_params is None:
plugin_params = {}
try:
plugin_ext = plugin_manager[plugin_name]
except KeyError:
raise DefinitionException(
_('No plugin named %(plugin)s available for '
'%(name)s') % dict(
plugin=plugin_name,
name=name), self.cfg)
plugin_class = plugin_ext.plugin
self.plugin = plugin_class(**plugin_params)
fields = cfg['fields']
else:
# Simple definition "foobar: jsonpath"
fields = cfg
if isinstance(fields, list):
# NOTE(mdragon): if not a string, we assume a list.
if len(fields) == 1:
fields = fields[0]
else:
fields = '|'.join('(%s)' % path for path in fields)
if isinstance(fields, six.integer_types):
self.getter = fields
else:
try:
self.getter = self.make_getter(fields)
except Exception as e:
raise DefinitionException(
_("Parse error in JSONPath specification "
"'%(jsonpath)s' for %(name)s: %(err)s")
% dict(jsonpath=fields, name=name, err=e), self.cfg)
def _get_path(self, match):
if match.context is not None:
for path_element in self._get_path(match.context):
yield path_element
yield str(match.path)
def parse(self, obj, return_all_values=False):
if callable(self.getter):
values = self.getter(obj)
else:
return self.getter
values = [match for match in values
if return_all_values or match.value is not None]
if self.plugin is not None:
if return_all_values and not self.plugin.support_return_all_values:
raise DefinitionException("Plugin %s don't allows to "
"return multiple values" %
self.cfg["plugin"]["name"], self.cfg)
values_map = [('.'.join(self._get_path(match)), match.value) for
match in values]
values = [v for v in self.plugin.trait_values(values_map)
if v is not None]
else:
values = [match.value for match in values if match is not None]
if return_all_values:
return values
else:
return values[0] if values else None
def make_getter(self, fields):
if fields in self.GETTERS_CACHE:
return self.GETTERS_CACHE[fields]
else:
getter = self.JSONPATH_RW_PARSER.parse(fields).find
self.GETTERS_CACHE[fields] = getter
return getter
def load_definitions(defaults, config_file, fallback_file=None):
"""Setup a definitions from yaml config file."""
if not os.path.exists(config_file):
config_file = cfg.CONF.find_file(config_file)
if not config_file and fallback_file is not None:
LOG.debug("No Definitions configuration file found!"
"Using default config.")
config_file = fallback_file
if config_file is not None:
LOG.debug("Loading definitions configuration file: %s", config_file)
with open(config_file) as cf:
config = cf.read()
try:
definition_cfg = yaml.safe_load(config)
except yaml.YAMLError as err:
if hasattr(err, 'problem_mark'):
mark = err.problem_mark
errmsg = (_("Invalid YAML syntax in Definitions file "
"%(file)s at line: %(line)s, column: %(column)s.")
% dict(file=config_file,
line=mark.line + 1,
column=mark.column + 1))
else:
errmsg = (_("YAML error reading Definitions file "
"%(file)s")
% dict(file=config_file))
LOG.error(errmsg)
raise
else:
LOG.debug("No Definitions configuration file found!"
"Using default config.")
definition_cfg = defaults
LOG.info(_LI("Definitions: %s"), definition_cfg)
return definition_cfg