296 lines
12 KiB
Python
296 lines
12 KiB
Python
# Copyright 2017 AT&T Intellectual Property. All other rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain 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,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import collections
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import copy
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from deckhand.engine import document
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from deckhand.engine import utils
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from deckhand import errors
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class DocumentLayering(object):
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"""Class responsible for handling document layering.
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Layering is controlled in two places:
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1. The `LayeringPolicy` control document, which defines the valid layers
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and their order of precedence.
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2. In the `metadata.layeringDefinition` section of normal
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(`metadata.schema=metadata/Document/v1.0`) documents.
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.. note::
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Only documents with the same `schema` are allowed to be layered
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together into a fully rendered document.
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"""
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SUPPORTED_METHODS = ('merge', 'replace', 'delete')
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LAYERING_POLICY_SCHEMA = 'deckhand/LayeringPolicy/v1.0'
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def __init__(self, documents):
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"""Contructor for ``DocumentLayering``.
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:param documents: List of YAML documents represented as dictionaries.
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"""
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self.documents = [document.Document(d) for d in documents]
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self._find_layering_policy()
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self.layered_docs = self._calc_document_children()
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def render(self):
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"""Perform layering on the set of `documents`.
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Each concrete document will undergo layering according to the actions
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defined by its `layeringDefinition`.
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:returns: the list of rendered documents (does not include layering
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policy document).
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"""
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# ``rendered_data_by_layer`` agglomerates the set of changes across all
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# actions across each layer for a specific document.
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rendered_data_by_layer = {}
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# NOTE(fmontei): ``global_docs`` represents the topmost documents in
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# the system. It should probably be impossible for more than 1
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# top-level doc to exist, but handle multiple for now.
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global_docs = [doc for doc in self.layered_docs
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if doc.get_layer() == self.layer_order[0]]
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for doc in global_docs:
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layer_idx = self.layer_order.index(doc.get_layer())
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rendered_data_by_layer[layer_idx] = doc.to_dict()
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# Keep iterating as long as a child exists.
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for child in doc.get_children(nested=True):
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# Retrieve the most up-to-date rendered_data (by
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# referencing the child's parent's data).
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child_layer_idx = self.layer_order.index(child.get_layer())
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rendered_data = rendered_data_by_layer[child_layer_idx - 1]
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# Apply each action to the current document.
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actions = child.get_actions()
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for action in actions:
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rendered_data = self._apply_action(
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action, child.to_dict(), rendered_data)
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# Update the actual document data if concrete.
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if not child.is_abstract():
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self.layered_docs[self.layered_docs.index(child)][
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'data'] = rendered_data['data']
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# Update ``rendered_data_by_layer`` for this layer so that
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# children in deeper layers can reference the most up-to-date
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# changes.
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rendered_data_by_layer[child_layer_idx] = rendered_data
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if 'children' in doc:
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del doc['children']
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return [d.to_dict() for d in self.layered_docs]
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def _apply_action(self, action, child_data, overall_data):
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"""Apply actions to each layer that is rendered.
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Supported actions include:
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* `merge` - a "deep" merge that layers new and modified data onto
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existing data
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* `replace` - overwrite data at the specified path and replace it
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with the data given in this document
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* `delete` - remove the data at the specified path
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"""
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method = action['method']
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if method not in self.SUPPORTED_METHODS:
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raise errors.UnsupportedActionMethod(
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action=action, document=child_data)
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# Use copy prevent these data from being updated referentially.
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overall_data = copy.deepcopy(overall_data)
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child_data = copy.deepcopy(child_data)
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rendered_data = overall_data
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# Remove empty string paths and ensure that "data" is always present.
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path = action['path'].split('.')
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path = [p for p in path if p != '']
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path.insert(0, 'data')
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last_key = 'data' if not path[-1] else path[-1]
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for attr in path:
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if attr == path[-1]:
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break
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rendered_data = rendered_data.get(attr)
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child_data = child_data.get(attr)
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if method == 'delete':
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# If the entire document is passed (i.e. the dict including
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# metadata, data, schema, etc.) then reset data to an empty dict.
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if last_key == 'data':
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rendered_data['data'] = {}
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elif last_key in rendered_data:
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del rendered_data[last_key]
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elif last_key not in rendered_data:
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# If the key does not exist in `rendered_data`, this is a
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# validation error.
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raise errors.MissingDocumentKey(
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child=child_data, parent=rendered_data, key=last_key)
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elif method == 'merge':
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if last_key in rendered_data and last_key in child_data:
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# If both entries are dictionaries, do a deep merge. Otherwise
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# do a simple merge.
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if (isinstance(rendered_data[last_key], dict)
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and isinstance(child_data[last_key], dict)):
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utils.deep_merge(
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rendered_data[last_key], child_data[last_key])
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else:
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rendered_data.setdefault(last_key, child_data[last_key])
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elif last_key in child_data:
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rendered_data.setdefault(last_key, child_data[last_key])
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else:
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# If the key does not exist in the child document, this is a
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# validation error.
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raise errors.MissingDocumentKey(
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child=child_data, parent=rendered_data, key=last_key)
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elif method == 'replace':
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if last_key in rendered_data and last_key in child_data:
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rendered_data[last_key] = child_data[last_key]
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elif last_key in child_data:
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rendered_data.setdefault(last_key, child_data[last_key])
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elif last_key not in child_data:
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# If the key does not exist in the child document, this is a
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# validation error.
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raise errors.MissingDocumentKey(
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child=child_data, parent=rendered_data, key=last_key)
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return overall_data
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def _find_layering_policy(self):
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"""Retrieve the current layering policy.
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:raises LayeringPolicyMalformed: If the `layerOrder` could not be
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found in the LayeringPolicy or if it is not a list.
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:raises LayeringPolicyNotFound: If system has no layering policy.
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"""
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# TODO(fmontei): There should be a DB call here to fetch the layering
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# policy from the DB.
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for doc in self.documents:
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if doc.to_dict()['schema'] == self.LAYERING_POLICY_SCHEMA:
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self.layering_policy = doc
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break
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if not hasattr(self, 'layering_policy'):
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raise errors.LayeringPolicyNotFound(
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schema=self.LAYERING_POLICY_SCHEMA)
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# TODO(fmontei): Rely on schema validation or some such for this.
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try:
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self.layer_order = list(self.layering_policy['data']['layerOrder'])
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except KeyError:
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raise errors.LayeringPolicyMalformed(
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schema=self.LAYERING_POLICY_SCHEMA,
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document=self.layering_policy)
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if not isinstance(self.layer_order, list):
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raise errors.LayeringPolicyMalformed(
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schema=self.LAYERING_POLICY_SCHEMA,
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document=self.layering_policy)
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def _calc_document_children(self):
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"""Determine each document's children.
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For each document, attempts to find the document's children. Adds a new
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key called "children" to the document's dictionary.
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.. note::
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A document should only have exactly one parent.
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If a document does not have a parent, then its layer must be
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the topmost layer defined by the `layerOrder`.
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:returns: Ordered list of documents that need to be layered. Each
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document contains a "children" property in addition to original
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data. List of documents returned is ordered from highest to lowest
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layer.
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:rtype: list of deckhand.engine.document.Document objects.
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:raises IndeterminateDocumentParent: If more than one parent document
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was found for a document.
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:raises MissingDocumentParent: If the parent document could not be
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found. Only applies documents with `layeringDefinition` property.
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"""
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layered_docs = list(
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filter(lambda x: 'layeringDefinition' in x['metadata'],
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self.documents))
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# ``all_children`` is a counter utility for verifying that each
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# document has exactly one parent.
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all_children = collections.Counter()
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def _get_children(doc):
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children = []
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doc_layer = doc.get_layer()
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try:
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next_layer_idx = self.layer_order.index(doc_layer) + 1
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children_doc_layer = self.layer_order[next_layer_idx]
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except IndexError:
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# The lowest layer has been reached, so no children. Return
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# empty list.
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return children
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for other_doc in layered_docs:
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# Documents with different schemas are never layered together,
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# so consider only documents with same schema as candidates.
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if (other_doc.get_layer() == children_doc_layer
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and other_doc.get_schema() == doc.get_schema()):
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# A document can have many labels but should only have one
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# explicit label for the parentSelector.
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parent_sel = other_doc.get_parent_selector()
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parent_sel_key = list(parent_sel.keys())[0]
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parent_sel_val = list(parent_sel.values())[0]
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doc_labels = doc.get_labels()
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if (parent_sel_key in doc_labels and
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parent_sel_val == doc_labels[parent_sel_key]):
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children.append(other_doc)
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return children
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for layer in self.layer_order:
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docs_by_layer = list(filter(
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(lambda x: x.get_layer() == layer), layered_docs))
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for doc in docs_by_layer:
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children = _get_children(doc)
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if children:
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all_children.update(children)
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doc.to_dict().setdefault('children', children)
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all_children_elements = list(all_children.elements())
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secondary_docs = list(
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filter(lambda d: d.get_layer() != self.layer_order[0],
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layered_docs))
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for doc in secondary_docs:
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# Unless the document is the topmost document in the
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# `layerOrder` of the LayeringPolicy, it should be a child document
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# of another document.
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if doc not in all_children_elements:
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raise errors.MissingDocumentParent(document=doc)
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# If the document is a child document of more than 1 parent, then
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# the document has too many parents, which is a validation error.
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elif all_children[doc] != 1:
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raise errors.IndeterminateDocumentParent(document=doc)
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return layered_docs
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