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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
#
# 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 collections
import warnings
import six
from heat.common.i18n import _
from heat.engine import constraints as constr
from heat.engine import support
class Schema(constr.Schema):
"""
Simple schema class for attributes.
Schema objects are serialisable to dictionaries following a superset of
the HOT input Parameter schema using dict().
"""
KEYS = (
DESCRIPTION,
) = (
'description',
)
CACHE_MODES = (
CACHE_LOCAL,
CACHE_NONE
) = (
'cache_local',
'cache_none'
)
def __init__(self, description=None,
support_status=support.SupportStatus(),
cache_mode=CACHE_LOCAL):
self.description = description
self.support_status = support_status
self.cache_mode = cache_mode
def __getitem__(self, key):
if key == self.DESCRIPTION:
if self.description is not None:
return self.description
raise KeyError(key)
@classmethod
def from_attribute(cls, schema_dict):
"""
Return a Property Schema corresponding to a Attribute Schema.
"""
if isinstance(schema_dict, cls):
return schema_dict
warnings.warn('<name>: <description> schema definition is deprecated. '
'Use <name>: attributes.Schema(<description>) instead.',
DeprecationWarning)
return cls(schema_dict)
def schemata(schema):
"""
Return dictionary of Schema objects for given dictionary of schemata.
"""
return dict((n, Schema.from_attribute(s)) for n, s in schema.items())
class Attribute(object):
"""
An Attribute schema.
"""
def __init__(self, attr_name, schema):
"""
Initialise with a name and description.
:param attr_name: the name of the attribute
:param schema: attribute schema
"""
self.name = attr_name
self.schema = Schema.from_attribute(schema)
def support_status(self):
return self.schema.support_status
def as_output(self, resource_name):
"""
Return an Output schema entry for a provider template with the given
resource name.
:param resource_name: the logical name of the provider resource
:returns: This attribute as a template 'Output' entry
"""
return {
"Value": '{"Fn::GetAtt": ["%s", "%s"]}' % (resource_name,
self.name),
"Description": self.schema.description
}
class Attributes(collections.Mapping):
"""Models a collection of Resource Attributes."""
def __init__(self, res_name, schema, resolver):
self._resource_name = res_name
self._resolver = resolver
self._attributes = Attributes._make_attributes(schema)
self.reset_resolved_values()
def reset_resolved_values(self):
self._resolved_values = {}
@staticmethod
def _make_attributes(schema):
return dict((n, Attribute(n, d)) for n, d in schema.items())
@staticmethod
def as_outputs(resource_name, resource_class):
"""
:param resource_name: logical name of the resource
:param resource_class: resource implementation class
:returns: The attributes of the specified resource_class as a template
Output map
"""
schema = resource_class.attributes_schema
attribs = Attributes._make_attributes(schema).items()
return dict((n, att.as_output(resource_name)) for n, att in attribs)
@staticmethod
def schema_from_outputs(json_snippet):
if json_snippet:
return dict((k, Schema(v.get("Description")))
for k, v in json_snippet.items())
return {}
def __getitem__(self, key):
if key not in self:
raise KeyError(_('%(resource)s: Invalid attribute %(key)s') %
dict(resource=self._resource_name, key=key))
attrib = self._attributes.get(key)
if attrib.schema.cache_mode == Schema.CACHE_NONE:
return self._resolver(key)
if key in self._resolved_values:
return self._resolved_values[key]
value = self._resolver(key)
if value is not None:
# only store if not None, it may resolve to an actual value
# on subsequent calls
self._resolved_values[key] = value
return value
def __len__(self):
return len(self._attributes)
def __contains__(self, key):
return key in self._attributes
def __iter__(self):
return iter(self._attributes)
def __repr__(self):
return ("Attributes for %s:\n\t" % self._resource_name +
'\n\t'.join(self._attributes.values()))
def select_from_attribute(attribute_value, path):
'''
Select an element from an attribute value.
:param attribute_value: the attribute value.
:param path: a list of path components to select from the attribute.
:returns: the selected attribute component value.
'''
def get_path_component(collection, key):
if not isinstance(collection, (collections.Mapping,
collections.Sequence)):
raise TypeError(_("Can't traverse attribute path"))
if not isinstance(key, (six.string_types, int)):
raise TypeError(_('Path components in attributes must be strings'))
return collection[key]
try:
return reduce(get_path_component, path, attribute_value)
except (KeyError, IndexError, TypeError):
return None
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