This GIST shows how to use configparser to interpolate env variables within

config.py

import configparser
import os

class CustomEnvInterpolation(configparser.BasicInterpolation):
    """Interpolation which expands environment variables in values."""

    def before_get(self, parser, section, option, value, defaults):
        super().before_get(parser, section, option, value, defaults)

        if not os.environ.get('MY_ENV'):
            os.environ['MY_ENV'] = 'default'
        return os.path.expandvars(value)

config = configparser.ConfigParser(interpolation=CustomEnvInterpolation())

def load_config():
    config.read('settings.cfg')


load_config()

print(os.environ.get('MY_ENV'))
print(config['settings']['environ'])

settings.cfg

[settings]
name = kyalo
environ = ${MY_ENV}