conf.json

{"id": 1}

conf.py

# coding: utf-8

import json


def load_conf(conf_file="conf.json"):
	with open(conf_file) as conf:
		try:
			return json.load(conf)
		except ValueError:
			return {}


def save_conf(data, conf_file="conf.json"):
	conf = load_conf(conf_file)
	conf.update(data)
	with open(conf_file, "w") as file_:
		json.dump(conf, file_)


if __name__ == '__main__':

	from tempfile import NamedTemporaryFile

	with NamedTemporaryFile() as temp:
		save_conf({'id': 1}, conf_file=temp.name)

		data = load_conf(temp.name)

		assert data == {'id': 1}