我想要的是

在 terraform 中，我有一张地图service_map：

variable "service_map" {
  type        = map
  description = "Map of some services and their ports."
  default     = {
    "dns"    = "53"
    "web"    = "443"
    "ssh"    = "22"
    "proxy"  = ""
  }
}

要在 AWS 上创建 LB 侦听器，我想调用资源aws_lb_listener，循环遍历地图service_map，跳过所有没有值的项目（在本例中，仅跳过proxy）：

resource "aws_lb_listener" "listeners" {
  for_each          = var.service_map
  load_balancer_arn = aws_lb.all_lbs[each.key].arn
  port              = each.value
  protocol          = each.key != "dns" ? "TCP" : "TCP_UDP"
  default_action {
    type             = "forward"
    target_group_arn = …