Internal module resource access

Terraform
1

So, I’m refactoring some legacy code, which which there was a project with multiple tf files, and turning it into a module being called by a driver project.

so say there’s a driver module on the “driver” directory:

driver/main.tf

module "old_module" {
  source = "../old-module-dir"

param1 = var.old-value1
}

old-value1 represents a value that used to be a local or a var in the old module, that’s now being populated by the driver before calling it.

In old-module-dir there are two files in question:

aws-hosts.tf:

locals {
   sgs = {
     "tag" = aws_security_group.one.id
   }

(stuff happens)

in aws-net.tf:

resource "aws_security_group" "one" {
  stuff that does create the sg if I apply
}

If I apply it, I get an error from aws-hosts that

"tag" = aws_security_group.one

A managed resource "aws_security_group" "consul-server-ap-southwest-1" has not been declared in old_module.

If I comment out the bit in aws-hosts.tf, I’ll get a module.old_module.aws_security_group.one will be created

If I reference it that way I get a `no module call named “old_module” is declared in old_module.

So how the heck do I write a reference to the resource that the module I’m in is creating?