variable "foo" { default = "bar" description = "bar" } variable "groups" { } provider "aws" { access_key = "foo" secret_key = "bar" } provider "do" { api_key = "${var.foo}" } resource "aws_security_group" "firewall" { count = 5 } resource aws_instance "web" { ami = "${var.foo}" security_groups = [ "foo", "${aws_security_group.firewall.foo}", "${element(split(\",\", var.groups)}", ] network_interface = { device_index = 0 description = "Main network interface" } } resource "aws_instance" "db" { security_groups = "${aws_security_group.firewall.*.id}" VPC = "foo" depends_on = ["aws_instance.web"] } output "web_ip" { value = "${aws_instance.web.private_ip}" }