229 lines
8.0 KiB
Python
229 lines
8.0 KiB
Python
#
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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 abc
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import collections
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import functools
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from heat.common import exception
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from heat.db import api as db_api
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from heat.engine import plugin_manager
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__all__ = ['Template']
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DEFAULT_VERSION = ('HeatTemplateFormatVersion', '2012-12-12')
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_template_classes = None
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class TemplatePluginManager(object):
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'''A Descriptor class for caching PluginManagers.
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Keeps a cache of PluginManagers with the search directories corresponding
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to the package containing the owner class.
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'''
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def __init__(self):
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self.plugin_managers = {}
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@staticmethod
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def package_name(obj_class):
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'''Return the package containing the given class.'''
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module_name = obj_class.__module__
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return module_name.rsplit('.', 1)[0]
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def __get__(self, obj, obj_class):
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'''Get a PluginManager for a class.'''
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pkg = self.package_name(obj_class)
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if pkg not in self.plugin_managers:
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self.plugin_managers[pkg] = plugin_manager.PluginManager(pkg)
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return self.plugin_managers[pkg]
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def get_version(template_data, available_versions):
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version_keys = set(key for key, version in available_versions)
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candidate_keys = set(k for k, v in template_data.iteritems() if
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isinstance(v, basestring))
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keys_present = version_keys & candidate_keys
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if not keys_present:
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return DEFAULT_VERSION
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if len(keys_present) > 1:
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explanation = _('Ambiguous versions (%s)') % ', '.join(keys_present)
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raise exception.InvalidTemplateVersion(explanation=explanation)
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version_key = keys_present.pop()
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return version_key, template_data[version_key]
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def get_template_class(plugin_mgr, template_data):
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global _template_classes
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if _template_classes is None:
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tmpl_mapping = plugin_manager.PluginMapping('template')
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_template_classes = dict(tmpl_mapping.load_all(plugin_mgr))
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available_versions = _template_classes.keys()
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version = get_version(template_data, available_versions)
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version_type = version[0]
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try:
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return _template_classes[version]
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except KeyError:
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av_list = [v for k, v in available_versions if k == version_type]
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msg_data = {'version': ': '.join(version),
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'version_type': version_type,
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'available': ', '.join(v for v in av_list)}
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if len(av_list) > 1:
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explanation = _('"%(version)s". "%(version_type)s" '
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'should be one of: %(available)s') % msg_data
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else:
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explanation = _('"%(version)s". "%(version_type)s" '
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'should be: %(available)s') % msg_data
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raise exception.InvalidTemplateVersion(explanation=explanation)
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class Template(collections.Mapping):
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'''A stack template.'''
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_plugins = TemplatePluginManager()
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_functionmaps = {}
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def __new__(cls, template, *args, **kwargs):
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'''Create a new Template of the appropriate class.'''
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if cls != Template:
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TemplateClass = cls
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else:
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TemplateClass = get_template_class(cls._plugins, template)
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return super(Template, cls).__new__(TemplateClass)
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def __init__(self, template, template_id=None, files=None):
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'''
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Initialise the template with a JSON object and a set of Parameters
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'''
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self.id = template_id
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self.t = template
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self.files = files or {}
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self.maps = self[self.MAPPINGS]
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self.version = get_version(self.t, _template_classes.keys())
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@classmethod
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def load(cls, context, template_id):
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'''Retrieve a Template with the given ID from the database.'''
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t = db_api.raw_template_get(context, template_id)
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return cls(t.template, template_id=template_id, files=t.files)
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def store(self, context=None):
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'''Store the Template in the database and return its ID.'''
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if self.id is None:
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rt = {
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'template': self.t,
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'files': self.files
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}
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new_rt = db_api.raw_template_create(context, rt)
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self.id = new_rt.id
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return self.id
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def __iter__(self):
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'''Return an iterator over the section names.'''
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return (s for s in self.SECTIONS
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if s not in self.SECTIONS_NO_DIRECT_ACCESS)
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def __len__(self):
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'''Return the number of sections.'''
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return len(self.SECTIONS) - len(self.SECTIONS_NO_DIRECT_ACCESS)
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@abc.abstractmethod
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def param_schemata(self):
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'''Return a dict of parameters.Schema objects for the parameters.'''
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pass
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@abc.abstractmethod
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def parameters(self, stack_identifier, user_params, validate_value=True,
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context=None):
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'''Return a parameters.Parameters object for the stack.'''
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pass
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def functions(self):
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'''Return a dict of template functions keyed by name.'''
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if self.version not in self._functionmaps:
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mappings = plugin_manager.PluginMapping('function', *self.version)
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funcs = dict(mappings.load_all(self._plugins))
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self._functionmaps[self.version] = funcs
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return self._functionmaps[self.version]
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def parse(self, stack, snippet):
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return parse(self.functions(), stack, snippet)
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def validate(self, allow_empty=True):
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'''Validate the template.
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Validates the top-level sections of the template as well as syntax
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inside select sections. Some sections are not checked here but in
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code parts that are responsible for working with the respective
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sections (e.g. parameters are check by parameters schema class).
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:param allow_empty: whether to allow an empty resources section
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'''
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# check top-level sections
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for k in self.t.keys():
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if k not in self.SECTIONS:
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raise exception.InvalidTemplateSection(section=k)
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# check resources
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tmpl_resources = self[self.RESOURCES]
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if not allow_empty and not tmpl_resources:
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message = _('The template is invalid. A Resources section with at '
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'least one resource must be defined.')
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raise exception.StackValidationFailed(message=message)
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for res in tmpl_resources.values():
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try:
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if not res.get('Type'):
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message = _('Every Resource object must '
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'contain a Type member.')
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raise exception.StackValidationFailed(message=message)
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except AttributeError:
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type_res = type(res)
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if isinstance(res, unicode):
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type_res = "string"
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message = _('Resources must contain Resource. '
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'Found a [%s] instead') % type_res
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raise exception.StackValidationFailed(message=message)
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def parse(functions, stack, snippet):
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recurse = functools.partial(parse, functions, stack)
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if isinstance(snippet, collections.Mapping):
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if len(snippet) == 1:
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fn_name, args = next(snippet.iteritems())
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Func = functions.get(fn_name)
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if Func is not None:
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return Func(stack, fn_name, recurse(args))
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return dict((k, recurse(v)) for k, v in snippet.iteritems())
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elif (not isinstance(snippet, basestring) and
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isinstance(snippet, collections.Iterable)):
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return [recurse(v) for v in snippet]
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else:
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return snippet
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