main.tf

variable "aws_account" { default = "" }
variable "aws_region" { default = "" }
variable "aws_access_key" { default = "" }
variable "aws_secret_key" { default = "" }
variable "development_l1" { default = "" }
variable "development_l2" { default = "" }
variable "operations_l1" { default = "" }
variable "operations_l2" { default = "" }

# setup AWS provider
provider "aws" {
  alias = "${var.aws_account}"
  region = "${var.aws_region}"
  access_key = "${var.aws_access_key}"
  secret_key = "${var.aws_secret_key}"
}

# create users
module "users" {
  source = "module"
  users = "${compact(concat(var.operations_l1,",",var.operations_l2,",",var.development_l1,",",var.development_l2))}"
}

module.tf

variable "aws_account" { default = "" }
variable "aws_region" { default = "" }
variable "aws_access_key" { default = "" }
variable "aws_secret_key" { default = "" }
variable "users" { default = "" }
variable "name" { default = "" }


# setup AWS provider
provider "aws" {
  alias = "${var.aws_account}"
  region = "${var.aws_region}"
  access_key = "${var.aws_access_key}"
  secret_key = "${var.aws_secret_key}"
}

resource "aws_iam_user" "user" {
  count = "${length(split(",", var.users))}"
  name  = "${element(split(",", var.users), count.index)}"
}

resource "aws_iam_access_key" "key" {
  count = "${length(split(",", var.users))}"
  user  = "${element(aws_iam_user.user.*.name, count.index)}"
}

variables.tfvars

development_l1 = "devuser1,devuser2"
development_l2 = "devuser3,devuser4"
operations_l1 = "opsuser1"
operations_l2 = "opsuser2,opsuser3"