How to deploy a flask application with a config file?

api
|_cofig
  |_config.py
|_app.py

from config.config import config
def create_app(app_environment=None):
    if app_environment is None:
        app = Flask(__name__)
        app.config.from_object(config[os.getenv('FLASK_ENV', 'dev')])
    else:
        app = Flask(__name__)
        app.config.from_object(config[app_environment])

if __name__ == "__main__":
    app = create_app(os.getenv('FLASK_ENV', 'dev'))
    app.run()

import os

class ProdConfig:
    # Database configuration
    API_TOKEN = os.environ.get('PROD_MARKET_STACK_API_KEY_SECRET')


class DevConfig:
    # Database configuration
    API_TOKEN = os.environ.get('API_KEY_SECRET')

class TestConfig:
    # Database configuration
    API_TOKEN = os.environ.get('MARKET_STACK_API_KEY')

config = {
    'dev': DevConfig,
    'test': TestConfig,
    'prod': ProdConfig
}

from flask import current_app
current_app.config['API_TOKEN']`