Hi@akhtar,
You can use the kubernetes_config_map resource in Terraform. This has the capability to create a ConfigMap as shown below.
resource "kubernetes_config_map" "dbconfig" {
   "metadata" {
       name = "dbconfig"
   }
   data = {
       dbconnection = "${var.project_id}:${var.region}:${google_sql_database_instance.master.name}"
   }
}