forked from borgmatic-collective/borgmatic
85 lines
3.0 KiB
Python
85 lines
3.0 KiB
Python
import logging
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import sys
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import warnings
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import pkg_resources
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import pykwalify.core
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import pykwalify.errors
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import ruamel.yaml.error
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def schema_filename():
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'''
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Path to the installed YAML configuration schema file, used to validate and parse the
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configuration.
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'''
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return pkg_resources.resource_filename('borgmatic', 'config/schema.yaml')
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class Validation_error(ValueError):
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'''
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A collection of error message strings generated when attempting to validate a particular
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configurartion file.
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'''
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def __init__(self, config_filename, error_messages):
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self.config_filename = config_filename
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self.error_messages = error_messages
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def parse_configuration(config_filename, schema_filename):
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'''
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Given the path to a config filename in YAML format and the path to a schema filename in
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pykwalify YAML schema format, return the parsed configuration as a data structure of nested
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dicts and lists corresponding to the schema. Example return value:
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{'location': {'source_directories': ['/home', '/etc'], 'repository': 'hostname.borg'},
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'retention': {'keep_daily': 7}, 'consistency': {'checks': ['repository', 'archives']}}
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Raise FileNotFoundError if the file does not exist, PermissionError if the user does not
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have permissions to read the file, or Validation_error if the config does not match the schema.
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'''
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warnings.simplefilter('ignore', ruamel.yaml.error.UnsafeLoaderWarning)
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logging.getLogger('pykwalify').setLevel(logging.CRITICAL)
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try:
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validator = pykwalify.core.Core(source_file=config_filename, schema_files=[schema_filename])
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except pykwalify.errors.CoreError as error:
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if 'do not exists on disk' in str(error):
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raise FileNotFoundError("No such file or directory: '{}'".format(config_filename))
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if 'Unable to load any data' in str(error):
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# If the YAML file has a syntax error, pykwalify's exception is particularly unhelpful.
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# So reach back to the originating exception from ruamel.yaml for something more useful.
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raise Validation_error(config_filename, (error.__context__,))
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raise
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parsed_result = validator.validate(raise_exception=False)
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if validator.validation_errors:
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raise Validation_error(config_filename, validator.validation_errors)
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return parsed_result
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def display_validation_error(validation_error):
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'''
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Given a Validation_error, display its error messages to stderr.
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'''
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print(
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'An error occurred while parsing a configuration file at {}:'.format(
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validation_error.config_filename
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),
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file=sys.stderr,
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)
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for error in validation_error.error_messages:
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print(error, file=sys.stderr)
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# FOR TESTING
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if __name__ == '__main__':
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try:
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configuration = parse_configuration('sample/config.yaml', schema_filename())
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print(configuration)
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except Validation_error as error:
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display_validation_error(error)
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