42de0c9a3c
Similar to properties, adds attribute_schema and attributes members to Resources in order to facilitate document generation and template provider stubs for resources. Change-Id: I5e207360816fbc685c66db68a7fab8afad11bf10 Implements: blueprint attributes-schema
136 lines
4.2 KiB
Python
136 lines
4.2 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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#
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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 collections
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class Attribute(object):
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"""
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An attribute description and resolved value.
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:param resource_name: the logical name of the resource having this
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attribute
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:param attr_name: the name of the attribute
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:param description: attribute description
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:param resolver: a function that will resolve the value of this attribute
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"""
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def __init__(self, attr_name, description, resolver):
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self._name = attr_name
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self._description = description
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self._resolve = resolver
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@property
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def name(self):
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"""
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:returns: The attribute name
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"""
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return self._name
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@property
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def value(self):
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"""
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:returns: The resolved attribute value
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"""
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return self._resolve(self._name)
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@property
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def description(self):
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"""
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:returns: A description of the attribute
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"""
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return self._description
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@staticmethod
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def as_output(resource_name, attr_name, description):
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"""
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:param resource_name: the logical name of a resource
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:param attr_name: the name of the attribute
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:description: the description of the attribute
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:returns: This attribute as a template 'Output' entry
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"""
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return {
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attr_name: {
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"Value": '{"Fn::GetAtt": ["%s", "%s"]}' % (resource_name,
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attr_name),
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"Description": description
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}
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}
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def __call__(self):
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return self.value
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def __str__(self):
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return ("Attribute %s: %s" % (self.name, self.value))
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class Attributes(collections.Mapping):
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"""Models a collection of Resource Attributes."""
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def __init__(self, res_name, schema, resolver):
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self._resource_name = res_name
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self._attributes = dict((k, Attribute(k, v, resolver))
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for k, v in schema.items())
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@property
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def attributes(self):
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"""
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Get a copy of the attribute definitions in this collection
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(as opposed to attribute values); useful for doc and
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template format generation
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:returns: attribute definitions
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"""
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# return a deep copy to avoid modification
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return dict((k, Attribute(k, v.description, v._resolve)) for k, v
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in self._attributes.items())
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@staticmethod
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def as_outputs(resource_name, resource_class):
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"""
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:param resource_name: logical name of the resource
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:param resource_class: resource implementation class
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:returns: The attributes of the specified resource_class as a template
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Output map
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"""
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outputs = {}
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for name, descr in resource_class.attributes_schema.items():
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outputs.update(Attribute.as_output(resource_name, name, descr))
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return outputs
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@staticmethod
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def schema_from_outputs(json_snippet):
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return dict(("Outputs.%s" % k, v.get("Description"))
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for k, v in json_snippet.items())
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def __getitem__(self, key):
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if key not in self:
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raise KeyError('%s: Invalid attribute %s' %
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(self._resource_name, key))
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return self._attributes[key]()
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def __len__(self):
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return len(self._attributes)
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def __contains__(self, key):
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return key in self._attributes
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def __iter__(self):
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return iter(self._attributes)
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def __repr__(self):
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return ("Attributes for %s:\n\t" % self._resource_name +
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'\n\t'.join(self._attributes.values()))
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