How to instantiate contents of rendered template_file? - amazon-web-services

Question

I have a template file that I use to on a list:
variable "users" {
type = "list"
default = [
"blackwidow",
"hulk",
"marvel",
]
}
// This will loop through the users list above and render out code for
// each item in the list.
data "template_file" "init" {
template = file("user_template.tpl")
count = length(var.users)
vars = {
username = var.users[count.index]
bucketid = aws_s3_bucket.myFTP_Bucket.id
}
}
The template file has multiple aws resources like
- "aws_transfer_user"
- "aws_s3_bucket_object"
- "aws_transfer_ssh_key"
etc... In fact it can have more stuff than just that. It also has some terraform variables in there too.
This data template works great in rendering out the contents of the template file, substituting in the names of my users.
But that's all terraform does.
Terraform doesn't instantiate the rendered content of the template file. It just merely keeps it as a string and keeps it in memory. Kind of like the C preprocessor doing substitution, but not 'including' the file.
Kind of frustrating. I'd like Terraform to instantiate the contents of my rendered template file. How do I do this?

Answer 1

The template_file data source (along with the templatefile function that has replaced it for Terraform 0.12) are for string templating, not for modular Terraform configuration.
To produce a set of different resource instances per item in a collection, we use resource for_each:
variable "users" {
type = set(string)
default = [
"blackwidow",
"hulk",
"marvel",
]
}
resource "aws_transfer_user" "example" {
for_each = var.users
# ...
}
resource "aws_transfer_user" "example" {
for_each = var.users
# ...
}
resource "aws_s3_bucket_object" "example" {
for_each = var.users
# ...
}
resource "aws_transfer_ssh_key" "example" {
for_each = aws_transfer_user.example
# ...
}
Inside each of those resource blocks you can use each.key to refer to each one of the usernames. Inside the resource "aws_transfer_ssh_key" "example" block, because I used aws_transfer_user.example as the repetition expression, you can also use each.value to access the attributes of the corresponding aws_transfer_user object. That for_each expression also serves to tell Terraform that aws_transfer_ssh_key.example depends on aws_transfer_user.example.