Terraform: conditionally reference a data source that may or may not exist

hack.tf

variable "yes" { default = true }

data "template_file" "maybe" {
  count    = "${ var.yes == false ? 0 : 1 }"
  template = "YES"
}

output "maybe" {
  value = "${ var.yes == false ? "" : element(concat(data.template_file.maybe.*.rendered, list("")), 0) }" # <-- :_(
}

thanks <3

it'll fail because Terraform will evaluate all variable in ternary operation before use
So if var.yes = true then it'll generate error because data.template_file. maybe is not defined