OpenStack Orchestration (Heat)
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# 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
# 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 collections
import copy
import itertools
import operator
import six
from heat.common import exception
from heat.common.i18n import repr_wrapper
from heat.engine import function
from heat.engine import properties
__all__ = ['ResourceDefinition']
# Field names that can be passed to Template.get_section_name() in order to
# determine the appropriate name for a particular template format.
) = (
'Type', 'Properties', 'Metadata', 'DeletionPolicy', 'UpdatePolicy',
'DependsOn', 'Description', 'external_id',
class ResourceDefinition(object):
"""A definition of a resource, independent of any template format."""
class Diff(object):
"""A diff between two versions of the same resource definition."""
def __init__(self, old_defn, new_defn):
if not (isinstance(old_defn, ResourceDefinition) and
isinstance(new_defn, ResourceDefinition)):
raise TypeError
self.old_defn = old_defn
self.new_defn = new_defn
def properties_changed(self):
"""Return True if the resource properties have changed."""
return self.old_defn._properties != self.new_defn._properties
def metadata_changed(self):
"""Return True if the resource metadata has changed."""
return self.old_defn._metadata != self.new_defn._metadata
def update_policy_changed(self):
"""Return True if the resource update policy has changed."""
return self.old_defn._update_policy != self.new_defn._update_policy
def __bool__(self):
"""Return True if anything has changed."""
return (self.properties_changed() or
self.metadata_changed() or
__nonzero__ = __bool__
) = (
'Delete', 'Retain', 'Snapshot',
def __init__(self, name, resource_type, properties=None, metadata=None,
depends=None, deletion_policy=None, update_policy=None,
description=None, external_id=None, condition=None):
"""Initialise with the parsed definition of a resource.
Any intrinsic functions present in any of the sections should have been
parsed into Function objects before constructing the definition.
:param name: The name of the resource (for use in error messages)
:param resource_type: The resource type
:param properties: A dictionary of supplied property values
:param metadata: The supplied metadata
:param depends: A list of resource names on which this resource depends
:param deletion_policy: The deletion policy for the resource
:param update_policy: A dictionary of supplied update policies
:param description: A string describing the resource
:param external_id: A uuid of an external resource
:param condition: A condition name associated with the resource
""" = name
self.resource_type = resource_type
self.description = description or ''
self._properties = properties
self._metadata = metadata
self._depends = depends
self._deletion_policy = deletion_policy
self._update_policy = update_policy
self._external_id = external_id
self._condition = condition
self._hash = hash(self.resource_type)
self._rendering = None
self._dep_names = None
self._all_dep_attrs = None
assert isinstance(self.description, six.string_types)
if properties is not None:
assert isinstance(properties, (collections.Mapping,
self._hash ^= _hash_data(properties)
if metadata is not None:
assert isinstance(metadata, (collections.Mapping,
self._hash ^= _hash_data(metadata)
if depends is not None:
assert isinstance(depends, (collections.Sequence,
assert not isinstance(depends, six.string_types)
self._hash ^= _hash_data(depends)
if deletion_policy is not None:
assert deletion_policy in self.DELETION_POLICIES
self._hash ^= _hash_data(deletion_policy)
if update_policy is not None:
assert isinstance(update_policy, (collections.Mapping,
self._hash ^= _hash_data(update_policy)
if external_id is not None:
assert isinstance(external_id, (six.string_types,
self._hash ^= _hash_data(external_id)
self._deletion_policy = self.RETAIN
if condition is not None:
assert isinstance(condition, (six.string_types, bool,
self._hash ^= _hash_data(condition)
def freeze(self, **overrides):
"""Return a frozen resource definition, with all functions resolved.
This return a new resource definition with fixed data (containing no
intrinsic functions). Named arguments passed to this method override
the values passed as arguments to the constructor.
if getattr(self, '_frozen', False) and not overrides:
return self
def arg_item(attr_name):
name = attr_name.lstrip('_')
if name in overrides:
value = overrides[name]
if not value and getattr(self, attr_name) is None:
value = None
value = function.resolve(getattr(self, attr_name))
return name, value
args = ('name', 'resource_type', '_properties', '_metadata',
'_depends', '_deletion_policy', '_update_policy',
'description', '_external_id', '_condition')
defn = type(self)(**dict(arg_item(a) for a in args))
defn._frozen = True
return defn
def reparse(self, stack, template):
"""Reinterpret the resource definition in the context of a new stack.
This returns a new resource definition, with all of the functions
parsed in the context of the specified stack and template.
assert not getattr(self, '_frozen', False
), "Cannot re-parse a frozen definition"
def reparse_snippet(snippet):
return template.parse(stack, copy.deepcopy(snippet))
return type(self)(, self.resource_type,
def dep_attrs(self, resource_name, load_all=False):
"""Iterate over attributes of a given resource that this references.
Return an iterator over dependent attributes for specified
resource_name in resources' properties and metadata fields.
if self._all_dep_attrs is None and load_all:
attr_map = collections.defaultdict(set)
atts = itertools.chain(function.all_dep_attrs(self._properties),
for res_name, att_name in atts:
self._all_dep_attrs = attr_map
if self._all_dep_attrs is not None:
return self._all_dep_attrs[resource_name]
return itertools.chain(function.dep_attrs(self._properties,
def required_resource_names(self):
"""Return a set of names of all resources on which this depends.
Note that this is done entirely in isolation from the rest of the
template, so the resource names returned may refer to resources that
don't actually exist, or would have strict_dependency=False. Use the
dependencies() method to get validated dependencies.
if self._dep_names is None:
explicit_depends = [] if self._depends is None else self._depends
def path(section):
return '.'.join([, section])
prop_deps = function.dependencies(self._properties,
metadata_deps = function.dependencies(self._metadata,
implicit_depends = rp:,
# (ricolin) External resource should not depend on any other
# resources. This operation is not allowed for now.
if self.external_id():
if explicit_depends:
raise exception.InvalidExternalResourceDependency(
self._dep_names = set()
self._dep_names = set(itertools.chain(explicit_depends,
return self._dep_names
def dependencies(self, stack):
"""Return the Resource objects in given stack on which this depends."""
def get_resource(res_name):
if res_name not in stack:
if res_name in stack.defn.all_rsrc_names():
# The resource is conditionally defined, allow dependencies
# on it
raise exception.InvalidTemplateReference(resource=res_name,
res = stack[res_name]
if getattr(res, 'strict_dependency', True):
return res
return six.moves.filter(None,,
def set_translation_rules(self, rules=None, client_resolve=True):
"""Helper method to update properties with translation rules."""
self._rules = rules or []
self._client_resolve = client_resolve
def properties(self, schema, context=None):
"""Return a Properties object representing the resource properties.
The Properties object is constructed from the given schema, and may
require a context to validate constraints.
props = properties.Properties(schema, self._properties or {},
function.resolve, context=context,
props.update_translation(self._rules, self._client_resolve)
return props
def deletion_policy(self):
"""Return the deletion policy for the resource.
The policy will be one of those listed in DELETION_POLICIES.
return function.resolve(self._deletion_policy) or self.DELETE
def update_policy(self, schema, context=None):
"""Return a Properties object representing the resource update policy.
The Properties object is constructed from the given schema, and may
require a context to validate constraints.
props = properties.Properties(schema, self._update_policy or {},
function.resolve, context=context,
props.update_translation(self._rules, self._client_resolve)
return props
def metadata(self):
"""Return the resource metadata."""
return function.resolve(self._metadata) or {}
def external_id(self):
"""Return the external resource id."""
return function.resolve(self._external_id)
def condition(self):
"""Return the name of the conditional inclusion rule, if any.
Returns None if the resource is included unconditionally.
return function.resolve(self._condition)
def render_hot(self):
"""Return a HOT snippet for the resource definition."""
if self._rendering is None:
attrs = {
'type': 'resource_type',
'properties': '_properties',
'metadata': '_metadata',
'deletion_policy': '_deletion_policy',
'update_policy': '_update_policy',
'depends_on': '_depends',
'external_id': '_external_id',
'condition': '_condition'
def rawattrs():
"""Get an attribute with function objects stripped out."""
for key, attr in attrs.items():
value = getattr(self, attr)
if value is not None:
yield key, copy.deepcopy(value)
self._rendering = dict(rawattrs())
return self._rendering
def __sub__(self, previous):
"""Calculate the difference between this definition and a previous one.
Return a Diff object that can be used to establish differences between
this definition and a previous definition of the same resource.
if not isinstance(previous, ResourceDefinition):
return NotImplemented
return self.Diff(previous, self)
def __eq__(self, other):
"""Compare this resource definition for equality with another.
Two resource definitions are considered to be equal if they can be
generated from the same template snippet. The name of the resource is
ignored, as are the actual values that any included functions resolve
if not isinstance(other, ResourceDefinition):
return NotImplemented
return self.render_hot() == other.render_hot()
def __ne__(self, other):
"""Compare this resource definition for inequality with another.
See __eq__() for the definition of equality.
equal = self.__eq__(other)
if equal is NotImplemented:
return NotImplemented
return not equal
def __hash__(self):
"""Return a hash value for this resource definition.
Resource definitions that compare equal will have the same hash. (In
particular, the resource name is *not* taken into account.) See
the __eq__() method for the definition of equality.
return self._hash
def __repr__(self):
"""Return a string representation of the resource definition."""
def arg_repr(arg_name):
return '='.join([arg_name, repr(getattr(self, '_%s' % arg_name))])
args = ('properties', 'metadata', 'depends',
'deletion_policy', 'update_policy', 'condition')
data = {
'classname': type(self).__name__,
'name': repr(,
'type': repr(self.resource_type),
'args': ', '.join(arg_repr(n) for n in args)
return '%(classname)s(%(name)s, %(type)s, %(args)s)' % data
def _hash_data(data):
"""Return a stable hash value for an arbitrary parsed-JSON data snippet."""
if isinstance(data, function.Function):
data = copy.deepcopy(data)
if not isinstance(data, six.string_types):
if isinstance(data, collections.Sequence):
return hash(tuple(_hash_data(d) for d in data))
if isinstance(data, collections.Mapping):
item_hashes = (hash(k) ^ _hash_data(v) for k, v in data.items())
return six.moves.reduce(operator.xor, item_hashes, 0)
return hash(data)