Python env vars apply to config

apply_env_vars.py

def apply_env_vars(module_name, env_var_prefix='productname', remove_module_prefix='config.'):
    import os
    import sys
    env_var_prefix = '_'.join(
        env_var_prefix.upper().split('.') +
        module_name[len(remove_module_prefix):].upper().split('.')
    ) + '__'
    module = sys.modules[module_name]
    prefix_len = len(env_var_prefix)

    for key in os.environ.keys():
        if key.startswith(env_var_prefix):
            value = os.environ[key]
            key = key[prefix_len:]

            original_value = getattr(module, key, None)
            if original_value is not None:
                value = type(original_value)(value)

            setattr(module, key, value)