Terraform count on aws_instance resource

main.tf

variable "instances" {}
variable "flavor" {}
variable "ami" {}
variable "ami_list" {}

resource "aws_instance" "default" {
  count = "${var.instances}"
  ami = "${var.ami}"
  instance_type = "${var.flavor}"
}

resource "aws_instance" "varied" {
  count = "${var.instances}"
  ami = "${element(split(",", var.ami_list), count.index)}"
  instance_type = "${var.flavor}"
}