I will share my experience of resolving issues encountered while operating Kafka.

Issue

One day, I received an urgent contact from CS.

There was an issue where users were unable to register the coupon code

At first, I thought there might be an issue with the coupons, so I examined the error logs.

but for over 2 hours, there was no data for new user registrations.

Background

The current user registration flow is as follows:

1. The account service receives a request for user registration.
2. The account service stores member information and enables automatic login.
3. The account service sends a registration event to the Kafka broker.
4. The Babyface service receives the Kafka event and stores the member data.

The most likely reasons for "member information not being saved in the main DB" were the following two:

1. Data loss in the account service