Simple, configuration-driven backup software for servers and workstations
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import logging
import os
import ruamel.yaml
logger = logging.getLogger(__name__)
def load_configuration(filename):
'''
Load the given configuration file and return its contents as a data structure of nested dicts
and lists.
Raise ruamel.yaml.error.YAMLError if something goes wrong parsing the YAML, or RecursionError
if there are too many recursive includes.
'''
yaml = ruamel.yaml.YAML(typ='safe')
yaml.Constructor = Include_constructor
return yaml.load(open(filename))
def include_configuration(loader, filename_node):
'''
Load the given YAML filename (ignoring the given loader so we can use our own), and return its
contents as a data structure of nested dicts and lists.
'''
return load_configuration(os.path.expanduser(filename_node.value))
class Include_constructor(ruamel.yaml.SafeConstructor):
'''
A YAML "constructor" (a ruamel.yaml concept) that supports a custom "!include" tag for including
separate YAML configuration files. Example syntax: `retention: !include common.yaml`
'''
def __init__(self, preserve_quotes=None, loader=None):
super(Include_constructor, self).__init__(preserve_quotes, loader)
self.add_constructor('!include', include_configuration)
def flatten_mapping(self, node):
'''
Support the special case of shallow merging included configuration into an existing mapping
using the YAML '<<' merge key. Example syntax:
```
retention:
keep_daily: 1
<<: !include common.yaml
```
'''
representer = ruamel.yaml.representer.SafeRepresenter()
for index, (key_node, value_node) in enumerate(node.value):
if key_node.tag == u'tag:yaml.org,2002:merge' and value_node.tag == '!include':
included_value = representer.represent_data(self.construct_object(value_node))
node.value[index] = (key_node, included_value)
super(Include_constructor, self).flatten_mapping(node)