Rendering template file

main.tf

data "template_file" "batch_policy_template" {
  template = "${file("${path.module}/batch_ecs_instance_policy.json.tpl")}"
  vars = {
    bucket_name = "${module.email_storage.name}"
  }
}
resource "aws_iam_role_policy" "test_policy" {
  name = "test_policy"
  role = "${aws_iam_role.aws_batch_service_role.id}"
  policy = "${data.template_file.batch_policy_template.rendered}"
}