Each operator is tracking the current state (status) of custom resource (CR) in K8s cluster (in this case this will be MariaDB operator resource) and compares to the desired state(specification) of custom resource.
All of that can be programmed.
Besides that each specification field can be configured to be required/optional

• Start by creating following *required* specifications:
  1. size - total number of servers (primary + replicas) Note: design decision was to go with Master/Slave replication (default will be 3)
  2. rootpwd - root password (no defaults)
  3. username - create replication user during the booting of server (could be default?)
  4. password - password for user that is create during container initialization (could be default?)
  5. database - custom database to be replicated (this could be optional?) (default would be test_mariadb)

• *Optional* specifications:
  1. data storage size - size of data directory
  2. port - exposed port for the service (default 3306)

• Track the current state by specifying
  1. current replicas - number of replicas being created
  2. database state - state of database - running/error

Set the custom format to represent the custom resource MariaDB.