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author | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
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committer | Matt A. Tobin <mattatobin@localhost.localdomain> | 2018-02-02 04:16:08 -0500 |
commit | 5f8de423f190bbb79a62f804151bc24824fa32d8 (patch) | |
tree | 10027f336435511475e392454359edea8e25895d /taskcluster/taskgraph/util/templates.py | |
parent | 49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff) | |
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Add m-esr52 at 52.6.0
Diffstat (limited to 'taskcluster/taskgraph/util/templates.py')
-rw-r--r-- | taskcluster/taskgraph/util/templates.py | 155 |
1 files changed, 155 insertions, 0 deletions
diff --git a/taskcluster/taskgraph/util/templates.py b/taskcluster/taskgraph/util/templates.py new file mode 100644 index 000000000..97620fa75 --- /dev/null +++ b/taskcluster/taskgraph/util/templates.py @@ -0,0 +1,155 @@ +# This Source Code Form is subject to the terms of the Mozilla Public +# License, v. 2.0. If a copy of the MPL was not distributed with this +# file, You can obtain one at http://mozilla.org/MPL/2.0/. + +from __future__ import absolute_import, print_function, unicode_literals + +import os + +import pystache +import yaml +import copy + +# Key used in template inheritance... +INHERITS_KEY = '$inherits' + + +def merge_to(source, dest): + ''' + Merge dict and arrays (override scalar values) + + Keys from source override keys from dest, and elements from lists in source + are appended to lists in dest. + + :param dict source: to copy from + :param dict dest: to copy to (modified in place) + ''' + + for key, value in source.items(): + # Override mismatching or empty types + if type(value) != type(dest.get(key)): # noqa + dest[key] = source[key] + continue + + # Merge dict + if isinstance(value, dict): + merge_to(value, dest[key]) + continue + + if isinstance(value, list): + dest[key] = dest[key] + source[key] + continue + + dest[key] = source[key] + + return dest + + +def merge(*objects): + ''' + Merge the given objects, using the semantics described for merge_to, with + objects later in the list taking precedence. From an inheritance + perspective, "parents" should be listed before "children". + + Returns the result without modifying any arguments. + ''' + if len(objects) == 1: + return copy.deepcopy(objects[0]) + return merge_to(objects[-1], merge(*objects[:-1])) + + +class TemplatesException(Exception): + pass + + +class Templates(): + ''' + The taskcluster integration makes heavy use of yaml to describe tasks this + class handles the loading/rendering. + ''' + + def __init__(self, root): + ''' + Initialize the template render. + + :param str root: Root path where to load yaml files. + ''' + if not root: + raise TemplatesException('Root is required') + + if not os.path.isdir(root): + raise TemplatesException('Root must be a directory') + + self.root = root + + def _inherits(self, path, obj, properties, seen): + blueprint = obj.pop(INHERITS_KEY) + seen.add(path) + + # Resolve the path here so we can detect circular references. + template = self.resolve_path(blueprint.get('from')) + variables = blueprint.get('variables', {}) + + # Passed parameters override anything in the task itself. + for key in properties: + variables[key] = properties[key] + + if not template: + msg = '"{}" inheritance template missing'.format(path) + raise TemplatesException(msg) + + if template in seen: + msg = 'Error while handling "{}" in "{}" circular template' + \ + 'inheritance seen \n {}' + raise TemplatesException(msg.format(path, template, seen)) + + try: + out = self.load(template, variables, seen) + except TemplatesException as e: + msg = 'Error expanding parent ("{}") of "{}" original error {}' + raise TemplatesException(msg.format(template, path, str(e))) + + # Anything left in obj is merged into final results (and overrides) + return merge_to(obj, out) + + def render(self, path, content, parameters, seen): + ''' + Renders a given yaml string. + + :param str path: used to prevent infinite recursion in inheritance. + :param str content: Of yaml file. + :param dict parameters: For mustache templates. + :param set seen: Seen files (used for inheritance) + ''' + content = pystache.render(content, parameters) + result = yaml.load(content) + + # In addition to the usual template logic done by mustache we also + # handle special '$inherit' dict keys. + if isinstance(result, dict) and INHERITS_KEY in result: + return self._inherits(path, result, parameters, seen) + + return result + + def resolve_path(self, path): + return os.path.join(self.root, path) + + def load(self, path, parameters=None, seen=None): + ''' + Load an render the given yaml path. + + :param str path: Location of yaml file to load (relative to root). + :param dict parameters: To template yaml file with. + ''' + seen = seen or set() + + if not path: + raise TemplatesException('path is required') + + path = self.resolve_path(path) + + if not os.path.isfile(path): + raise TemplatesException('"{}" is not a file'.format(path)) + + content = open(path).read() + return self.render(path, content, parameters, seen) |