https://blog.gongquiz.com/2022/11/24/%ed%8e%98%ec%9d%bc%ec%84%b8%ec%9d%b4%ed%94%84fail-safe%ea%b5%ac%ec%a1%b0%ec%9d%98-%ea%b0%80%ec%9e%a5-%ed%81%b0-%ed%8a%b9%ec%84%b1%ec%9d%80-%ed%95%ad%ea%b3%b5%ea%b8%b0%ec%b2%b4%ec%a0%95%eb%b9%84/