secrets.py

"""
Expands `${MY_VAR}` variables in a given dictionary from `os.environ` and
local INI-like file.
"""

import os


def load_secrets(filename):
    """
    Load secrets file in INI-like format and return dictionary of the items.
    """
    secrets = {}

    with open(filename) as f:
        for line in f.readlines():
            line = line.strip()
            if line.startswith('#'):
                continue

            if '=' in line:
                key, value = line.split('=')
                secrets[key.strip()] = value.strip()
    return secrets


def load_secret_settings(settings, secrets_file):
    """
    For given `settings` dict and secret file it loads the secrets,
    puts them into `os.environ` and expands `settings` values from the environ.

    Usage of the settings values to be expanded:
        SOME_KEY = ${MY_ENV_VAR}
    """
    if os.path.isfile(secrets_file):
        for key, value in load_secrets(secrets_file).items():
            os.environ[key] = value

    return dict((key, os.path.expandvars(value)) for
                key, value in settings.items())