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132 lines
4.5 KiB
132 lines
4.5 KiB
"""Manager to read and modify config data in JSON files."""
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# Copyright (c) Jupyter Development Team.
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# Distributed under the terms of the Modified BSD License.
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import errno
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import glob
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import json
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import os
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import copy
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from traitlets.config import LoggingConfigurable
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from traitlets.traitlets import Unicode, Bool
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def recursive_update(target, new):
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"""Recursively update one dictionary using another.
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None values will delete their keys.
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"""
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for k, v in new.items():
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if isinstance(v, dict):
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if k not in target:
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target[k] = {}
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recursive_update(target[k], v)
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if not target[k]:
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# Prune empty subdicts
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del target[k]
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elif v is None:
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target.pop(k, None)
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else:
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target[k] = v
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def remove_defaults(data, defaults):
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"""Recursively remove items from dict that are already in defaults"""
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# copy the iterator, since data will be modified
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for key, value in list(data.items()):
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if key in defaults:
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if isinstance(value, dict):
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remove_defaults(data[key], defaults[key])
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if not data[key]: # prune empty subdicts
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del data[key]
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else:
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if value == defaults[key]:
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del data[key]
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class BaseJSONConfigManager(LoggingConfigurable):
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"""General JSON config manager
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Deals with persisting/storing config in a json file with optionally
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default values in a {section_name}.d directory.
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"""
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config_dir = Unicode('.')
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read_directory = Bool(True)
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def ensure_config_dir_exists(self):
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"""Will try to create the config_dir directory."""
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try:
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os.makedirs(self.config_dir, 0o755)
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except OSError as e:
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if e.errno != errno.EEXIST:
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raise
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def file_name(self, section_name):
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"""Returns the json filename for the section_name: {config_dir}/{section_name}.json"""
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return os.path.join(self.config_dir, section_name+'.json')
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def directory(self, section_name):
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"""Returns the directory name for the section name: {config_dir}/{section_name}.d"""
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return os.path.join(self.config_dir, section_name+'.d')
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def get(self, section_name, include_root=True):
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"""Retrieve the config data for the specified section.
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Returns the data as a dictionary, or an empty dictionary if the file
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doesn't exist.
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When include_root is False, it will not read the root .json file,
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effectively returning the default values.
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"""
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paths = [self.file_name(section_name)] if include_root else []
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if self.read_directory:
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pattern = os.path.join(self.directory(section_name), '*.json')
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# These json files should be processed first so that the
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# {section_name}.json take precedence.
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# The idea behind this is that installing a Python package may
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# put a json file somewhere in the a .d directory, while the
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# .json file is probably a user configuration.
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paths = sorted(glob.glob(pattern)) + paths
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self.log.debug('Paths used for configuration of %s: \n\t%s', section_name, '\n\t'.join(paths))
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data = {}
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for path in paths:
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if os.path.isfile(path):
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with open(path, encoding='utf-8') as f:
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recursive_update(data, json.load(f))
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return data
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def set(self, section_name, data):
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"""Store the given config data.
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"""
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filename = self.file_name(section_name)
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self.ensure_config_dir_exists()
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if self.read_directory:
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# we will modify data in place, so make a copy
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data = copy.deepcopy(data)
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defaults = self.get(section_name, include_root=False)
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remove_defaults(data, defaults)
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# Generate the JSON up front, since it could raise an exception,
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# in order to avoid writing half-finished corrupted data to disk.
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json_content = json.dumps(data, indent=2)
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f = open(filename, 'w', encoding='utf-8')
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with f:
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f.write(json_content)
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def update(self, section_name, new_data):
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"""Modify the config section by recursively updating it with new_data.
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Returns the modified config data as a dictionary.
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"""
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data = self.get(section_name)
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recursive_update(data, new_data)
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self.set(section_name, data)
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return data
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