Use Case: A MySQL instance will be running on production with required databases. I need to configure this running container as a master and spin up one more MySQL instance as a slave.

Challenges: Facing issues in configuring running MySQL instance as a master. The issue is not able to create replication user and not able to append the master/slave configuration to my.cnf file. The reason is,

1. To create replication user or to execute any custom SQL commands in container, we have to place initdb.sql with required SQL commands inside docker-entrypoint-initdb.d. So when container starting it execute the file present in docker-entrypoint-initdb.d and executes it, if the database had not created, if the database had created already it skips executing this .sql file residing in docker-entrypoint-initdb.d. This is the root for failing to configure master because MySQL is running with databases in production. So I cannot take this solution to configure as MySQL.
2. After facing this issue we planned to put the configuration SQL commands in .sh and keep in docker-entrypoint-initdb.d and execute them by patching the deployment. In this scenario we are facing some permission issues when executing the .sh files.

I need to configure replication(master-slave) for MySQL instance(s) in kubernetes world. I gone through the lot of posts to understand how to implement this. Nothing worked out as I am expecting and as I explained above. Along with this I found a custom image(bitnami/mysql) which supports setting up the replication, which I don't want use because finally I would not be able to implement this in production env.

So it will be very grateful if anyone helps me by suggesting any approach to solve this problem.

Thank you very much in advance.!!!