[SOLVED] How to change the existing cluster and instance admin username which is controlled by terraform?

How to change the existing cluster and instance admin username which is controlled by terraform?

Currently I have an existing Aurora PostgreSQL cluster running in Serverless v2 mode created by terraform.

    # AWS Aurora Cluster
resource "aws_rds_cluster" "aurora_cluster" {
  tags                            = var.tags
  cluster_identifier              = "my-db-${var.environment}"
  engine                          = "aurora-postgresql"
  engine_mode                     = "provisioned"
  engine_version                  = var.engine_version
  db_subnet_group_name            = aws_db_subnet_group.subnet_group.name
  database_name                   = "my-db"
  manage_master_user_password     = true
  master_username                 = "postgres"
  port                            = 5432
  storage_encrypted               = true
  vpc_security_group_ids          = [aws_security_group.allow_db_connection.id]
  apply_immediately               = true
  skip_final_snapshot             = true
  availability_zones              = var.availability_zones
  enabled_cloudwatch_logs_exports = [
    "postgresql"
  ]
  backup_retention_period = "7"

  serverlessv2_scaling_configuration {
    max_capacity = 10.0
    min_capacity = 1.0
  }
}


# AWS Aurora Instance
resource "aws_rds_cluster_instance" "aurora_instance" {
  tags                 = var.tags
  cluster_identifier   = "my-db-${var.environment}"
  identifier           = "my-db-${var.environment}"
  instance_class       = var.instance_class
  availability_zone    = var.availability_zone
  engine               = aws_rds_cluster.aurora_cluster.engine
  engine_version       = aws_rds_cluster.aurora_cluster.engine_version
  db_subnet_group_name = aws_db_subnet_group.subnet_group.name
}

AWS security hub is showing me following issues for it: RDS Database Clusters should use a custom administrator username RDS database instances should use a custom administrator username

I want to change it from "postgres" to custom name for cluster and instance. What should be the steps for it? I dont think we can simply modify the value of existing cluster. Should i create the new one ? take the snapshot of the exiting cluster and restore it ? but then restored snapshot will be new DB cluster i think.

Can someone help me with the process ?

Solution