Check all required settings have been provided

def check_required(self):
        """ Check all required settings have been provided
        """
        die = False
        for key, value in self.spec.items():
            if not getattr(self, key.upper()) and value['required']:
                print(f"{key} is a required setting. "
                      "Set via command-line params, env or file. "
                      "For examples, try '--generate' or '--help'.")
                die = True
        if die:
            sys.exit(1)