#!/usr/bin/env python # Copyright (C) 2013 Hewlett-Packard. # # 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. # Provides local yaml parsing classes and extend yaml module """Custom application specific yamls tags are supported to provide enhancements when reading yaml configuration. These allow inclusion of arbitrary files as a method of having blocks of data managed separately to the yaml job configurations. A specific usage of this is inlining scripts contained in separate files, although such tags may also be used to simplify usage of macros or job templates. The tag ``!include`` will treat the following string as file which should be parsed as yaml configuration data. Example: .. literalinclude:: /../../tests/localyaml/fixtures/include001.yaml The tag ``!include-raw`` will treat the following file as a data blob, which should be read into the calling yaml construct without any further parsing. Any data in a file included through this tag, will be treated as string data. Example: .. literalinclude:: /../../tests/localyaml/fixtures/include-raw001.yaml The tag ``!include-raw-escape`` treats the given file as a data blob, which should be escaped before being read in as string data. This allows job-templates to use this tag to include scripts from files without needing to escape braces in the original file. Example: .. literalinclude:: /../../tests/localyaml/fixtures/include-raw-escaped001.yaml """ import codecs try: from collections import OrderedDict except ImportError: from ordereddict import OrderedDict import functools import logging import re import os import yaml from yaml.constructor import BaseConstructor logger = logging.getLogger(__name__) class OrderedConstructor(BaseConstructor): """The default constructor class for PyYAML loading uses standard python dictionaries which can have randomized ordering enabled (default in CPython from version 3.3). The order of the XML elements being outputted is both important for tests and for ensuring predictable generation based on the source. This subclass overrides this behaviour to ensure that all dict's created make use of OrderedDict to have iteration of keys to always follow the order in which the keys were inserted/created. """ def construct_yaml_map(self, node): data = OrderedDict() yield data value = self.construct_mapping(node) if isinstance(node, yaml.MappingNode): self.flatten_mapping(node) else: raise yaml.constructor.ConstructorError( None, None, 'expected a mapping node, but found %s' % node.id, node.start_mark) mapping = OrderedDict() for key_node, value_node in node.value: key = self.construct_object(key_node, deep=False) try: hash(key) except TypeError as exc: raise yaml.constructor.ConstructorError( 'while constructing a mapping', node.start_mark, 'found unacceptable key (%s)' % exc, key_node.start_mark) value = self.construct_object(value_node, deep=False) mapping[key] = value data.update(mapping) class LocalLoader(OrderedConstructor, yaml.Loader): """Subclass for yaml.Loader which handles the local tags 'include', 'include-raw' and 'include-raw-escaped' to specify a file to include data from and whether to parse it as additional yaml, treat it as a data blob or additionally escape the data contained. These are specified in yaml files by "!include path/to/file.yaml". Constructor access a list of search paths to look under for the given file following each tag, taking the first match found. Search path by default will include the same directory as the yaml file and the current working directory. Loading:: # use the load function provided in this module import local_yaml data = local_yaml.load(open(fn)) # Loading by providing the alternate class to the default yaml load from local_yaml import LocalLoader data = yaml.load(open(fn), LocalLoader) # Loading with a search path from local_yaml import LocalLoader import functools data = yaml.load(open(fn), functools.partial(LocalLoader, search_path=['path'])) """ def __init__(self, *args, **kwargs): # make sure to pop off any local settings before passing to # the parent constructor as any unknown args may cause errors. self.search_path = set() if 'search_path' in kwargs: for p in kwargs.pop('search_path'): logger.debug("Adding '{0}' to search path for include tags" .format(p)) self.search_path.add(os.path.normpath(p)) if 'escape_callback' in kwargs: self._escape = kwargs.pop('escape_callback') super(LocalLoader, self).__init__(*args, **kwargs) # Add tag constructors self.add_constructor('!include', self._include_tag) self.add_constructor('!include-raw', self._include_raw_tag) self.add_constructor('!include-raw-escape', self._include_raw_escape_tag) # constructor to preserve order of maps and ensure that the order of # keys returned is consistent across multiple python versions self.add_constructor(yaml.resolver.BaseResolver.DEFAULT_MAPPING_TAG, type(self).construct_yaml_map) if isinstance(self.stream, file): self.search_path.add(os.path.normpath( os.path.dirname(self.stream.name))) self.search_path.add(os.path.normpath(os.path.curdir)) def _find_file(self, filename): for dirname in self.search_path: candidate = os.path.expanduser(os.path.join(dirname, filename)) if os.path.isfile(candidate): logger.info("Including file '{0}' from path '{0}'" .format(filename, dirname)) return candidate return filename def _include_tag(self, loader, node): filename = self._find_file(loader.construct_yaml_str(node)) with open(filename, 'r') as f: data = yaml.load(f, functools.partial(LocalLoader, search_path=self.search_path )) return data def _include_raw_tag(self, loader, node): filename = self._find_file(loader.construct_yaml_str(node)) try: with codecs.open(filename, 'r', 'utf-8') as f: data = f.read() except: logger.error("Failed to include file using search path: '{0}'" .format(':'.join(self.search_path))) raise return data def _include_raw_escape_tag(self, loader, node): return self._escape(self._include_raw_tag(loader, node)) def _escape(self, data): return re.sub(r'({|})', r'\1\1', data) def load(stream, **kwargs): return yaml.load(stream, functools.partial(LocalLoader, **kwargs))