resource "test_instance" "first_many" {
  count = 2
}

resource "test_instance" "one" {
  image = test_instance.first_many[0].id
}

resource "test_instance" "splat_of_one" {
  image = test_instance.one.*.id[0]
}

resource "test_instance" "second_many" {
  count           = length(test_instance.first_many)
  security_groups = test_instance.first_many[count.index].id
}