93 lines
3.0 KiB
Python
93 lines
3.0 KiB
Python
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# This file is part of the django-environ.
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#
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# Copyright (c) 2021-2022, Serghei Iakovlev <egrep@protonmail.ch>
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# Copyright (c) 2013-2021, Daniele Faraglia <daniele.faraglia@gmail.com>
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#
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# For the full copyright and license information, please view
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# the LICENSE.txt file that was distributed with this source code.
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"""Docker-style file variable support module."""
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import os
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from collections.abc import MutableMapping
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class FileAwareMapping(MutableMapping):
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"""
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A mapping that wraps os.environ, first checking for the existence of a key
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appended with ``_FILE`` whenever reading a value. If a matching file key is
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found then the value is instead read from the file system at this location.
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By default, values read from the file system are cached so future lookups
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do not hit the disk again.
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A ``_FILE`` key has higher precedence than a value is set directly in the
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environment, and an exception is raised if the file can not be found.
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"""
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def __init__(self, env=None, cache=True):
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"""
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Initialize the mapping.
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:param env:
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where to read environment variables from (defaults to
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``os.environ``)
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:param cache:
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cache environment variables read from the file system (defaults to
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``True``)
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"""
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self.env = env if env is not None else os.environ
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self.cache = cache
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self.files_cache = {}
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def __getitem__(self, key):
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if self.cache and key in self.files_cache:
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return self.files_cache[key]
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key_file = self.env.get(key + "_FILE")
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if key_file:
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with open(key_file) as f:
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value = f.read()
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if self.cache:
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self.files_cache[key] = value
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return value
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return self.env[key]
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def __iter__(self):
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"""
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Iterate all keys, also always including the shortened key if ``_FILE``
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keys are found.
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"""
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for key in self.env:
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yield key
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if key.endswith("_FILE"):
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no_file_key = key[:-5]
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if no_file_key and no_file_key not in self.env:
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yield no_file_key
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def __len__(self):
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"""
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Return the length of the file, also always counting shortened keys for
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any ``_FILE`` key found.
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"""
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return len(tuple(iter(self)))
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def __setitem__(self, key, value):
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self.env[key] = value
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if self.cache and key.endswith("_FILE"):
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no_file_key = key[:-5]
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if no_file_key and no_file_key in self.files_cache:
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del self.files_cache[no_file_key]
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def __delitem__(self, key):
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file_key = key + "_FILE"
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if file_key in self.env:
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del self[file_key]
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if key in self.env:
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del self.env[key]
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return
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if self.cache and key.endswith("_FILE"):
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no_file_key = key[:-5]
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if no_file_key and no_file_key in self.files_cache:
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del self.files_cache[no_file_key]
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del self.env[key]
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