Why ${path.module} points to the current directory ".", but not to the module directory?

Question

I have used the following code:

module "instance" {
  for_each               = var.worker_private_ip
  source                 = "../../modules/ec2"
  env                    = var.env
  project_name           = var.project_name
  ami                    = var.ami
  instance_type          = var.instance_type
  subnet_id              = module.vpc.subnet_id
  vpc_security_group_ids = [module.security_group.security_group_id]
  private_ip             = each.value
  key_name               = var.public_key_name
  user_data              = file("${path.module}/startup.sh.tpl")
}

When I send terraform plan/apply command, I receive an error

path.module is "."

│ Invalid value for "path" parameter: no file exists at "./startup.sh.tpl";

So, terraform searching for file in current directory, but I expect for searching in (../../modules/ec2/)

I have startup.sh.tpl file in module folder and if I set user_data to:

user_data              = file("../../modules/ec2/startup.sh.tpl")

everything is fine, also if I move sciprt to current directory everything ok too, plan and apply commands are correct

What am I doing wrong? Why ${path.module} points to the current directory ".", but not to ../../modules/ec2/?

Answer 1

From the docs:

path.module is the filesystem path of the module where the expression is placed.

This means that it will return the relative path between your project's root folder and the location where path.module is used.

For example:

• if you are using it in a .tf file which is inside your ../../modules/ec2/ folder, it will return ../../modules/ec2;
• if your are using it inside your main.tf (or any .tf file) in your project's root folder, it will return .

In your case, if the user data is inside the module, probably there would be need for it to make it as an input.