archey4/archey/configuration.py

100 lines
3.7 KiB
Python

"""Archey configuration module"""
import os
import sys
import json
from copy import deepcopy
from archey.constants import DEFAULT_CONFIG
from archey.singleton import Singleton
class Configuration(metaclass=Singleton):
"""
Values present in `archey.constants.DEFAULT_CONFIG` dictionary are required.
New optional values may be added with `update_recursive` method.
If a `config_path` is passed during instantiation, it will be loaded.
"""
def __init__(self, config_path=None):
# Deep-copy `DEFAULT_CONFIG` so we have a local copy to safely mutate.
self._config = deepcopy(DEFAULT_CONFIG)
# Let's "save" `STDERR` file descriptor for `suppress_warnings` option
self._stderr = sys.stderr
# If a `config_path` has been specified, (try to) load it directly.
if config_path:
self._load_configuration(config_path)
# If not, load each (optional) configuration file in a "regular" order.
else:
self._load_configuration('/etc/archey4/')
self._load_configuration(os.path.expanduser('~/.config/archey4/'))
self._load_configuration(os.getcwd())
def get(self, key, default=None):
"""
A binding method to imitate the `dict.get()` behavior.
"""
return self._config.get(key, default)
def _load_configuration(self, path):
"""
A method handling configuration loading from a JSON file.
It will try to load any `config.json` present under `path`.
"""
# If a previous configuration file has denied overriding...
if not self.get('allow_overriding'):
# ... don't load this one.
return
# If the specified `path` is a directory, append the file name we are looking for.
if os.path.isdir(path):
path = os.path.join(path, 'config.json')
try:
with open(path) as f_config:
self.update_recursive(self._config, json.load(f_config))
except FileNotFoundError:
return
# For backward compatibility with Python versions prior to 3.5.0
# we use `ValueError` instead of `json.JSONDecodeError`.
except ValueError as value_error:
print('Warning: {0} ({1})'.format(value_error, path), file=sys.stderr)
return
# If the user does not want any warning to appear : 2> /dev/null
if self.get('suppress_warnings'):
# One more if statement to avoid multiple `open` calls.
if sys.stderr == self._stderr:
sys.stderr = open(os.devnull, 'w')
else:
self._close_and_restore_sys_stderr()
@classmethod
def update_recursive(cls, old_dict, new_dict):
"""
A method for recursively merging dictionaries as `dict.update()` is not able to do this.
Original snippet taken from here : <https://gist.github.com/angstwad/bf22d1822c38a92ec0a9>
"""
for key, value in new_dict.items():
if key in old_dict \
and isinstance(old_dict[key], dict) \
and isinstance(value, dict):
cls.update_recursive(old_dict[key], value)
else:
old_dict[key] = value
def _close_and_restore_sys_stderr(self):
"""If modified, close current and restore `sys.stderr` to its original file descriptor"""
if sys.stderr != self._stderr:
sys.stderr.close()
sys.stderr = self._stderr
def __del__(self):
self._close_and_restore_sys_stderr()
def __iter__(self):
"""When used as an iterator, directly yield `_config` elements"""
return iter(self._config.items())