Flask config setup that utilizes a Singleton pattern to always return the same configuration instance when called multiple times. Could allow for other functions or methods to run and modify the config, and have those changes represented later on during app lifetime.

config.py

from os import environ
from logging.config import dictConfig

from werkzeug.security import generate_password_hash


class BaseConfig(object):

    def _config_logger(self):
        """
        Configures the log level for the various run configurations
        :return: None
        """
        pass

    def __init__(self):
        self.MAX_CONTENT_LENGTH = 1e6
        self._config_logger()


class ProdConfig(BaseConfig):

    def _config_logger(self):
        super(ProdConfig, self)._config_logger()
        dictConfig({
            "version": 1,
            "root": {
                "level": "ERROR"
            }})

    def __init__(self):
        super(ProdConfig, self).__init__()

        self.AUTH_TOKEN = environ["AUTH_TOKEN"]
        self.SECRET_KEY = environ["SECRET_KEY"]
        self.QWLB_URL_CREATE = environ["QWLB_URL_CREATE"]
        self.ELQ_URL = environ["ELQ_URL"]
        self.QWLB_API_USER = environ["QWLB_API_USER"]
        self.QWLB_API_PASSWORD = generate_password_hash(
            environ["QWLB_API_PASSWORD"])


class DevConfig(BaseConfig):

    def _config_logger(self):
        super(DevConfig, self)._config_logger()
        dictConfig({
            "version": 1,
            "root": {
                "level": "INFO"
            }})

    def __init__(self):
        super(DevConfig, self).__init__()
        self.DEBUG = True

        self.AUTH_TOKEN = "test"
        self.SECRET_KEY = "test"
        self.QWLB_URL_CREATE = "http://0.0.0.0:8080/test"
        self.ELQ_URL = "http://0.0.0.0:8080/test"
        self.QWLB_API_USER = "test"
        self.QWLB_API_PASSWORD = generate_password_hash("test")


class TestConfig(DevConfig):

    def _config_logger(self):
        super(DevConfig, self)._config_logger()
        dictConfig({
            "version": 1,
            "root": {
                "level": "DEBUG"
            }})

    def __init__(self):
        super(TestConfig, self).__init__()
        self.TESTING = True
        self.DEBUG = False


class GetConfig(object):

    _instance = None

    def __init__(self, namespace):

        if not self._instance:
            if namespace == 'test':
                config = TestConfig
            elif namespace == 'dev' \
                    or namespace == 'qwlb-dev':
                config = DevConfig
            else:
                config = ProdConfig

            self._instance = config()

    def __getattr__(self, name):
        return getattr(self._instance, name)


def get_config():
    return GetConfig(environ['NAMESPACE'])