terraform-locals-rds-username-variable-sanitation.tf

locals {
  # we have to fixup the master username before we use it, the AWS API will error out otherwise
  # RDS expects the username to be without hyphens and 16 characters at max. 'rdsadmin' is also
  # a forbidden username, though we don't validate that here.
  db_master_user_unsanitized = "${var.app_db_master_user}"

  # truncate to 16 characters, but deal with the fact that substr() will error out if you ask
  # for more characters than are in the string
  default_master_user_max_length = "16"

  master_user_length       = "${length(local.db_master_user_unsanitized)}"
  master_user_max_length   = "${local.master_user_length < local.default_master_user_max_length ? local.master_user_length : local.default_master_user_max_length}"
  db_master_user_truncated = "${substr(local.db_master_user_unsanitized, 0, local.master_user_max_length)}"

  # remove hyphens from the username
  db_master_user = "${replace(local.db_master_user_truncated, "-", "")}"
}