Large number inputs get changed by terragrunt

[e-r-holt]

Describe the bug

Numbers reaching into 17~19 digits get changed by terragrunt before making it to terraform for planning

Steps To Reproduce

1. Create a module that passes one input to an output value

   
   variable "some_number" {
   type = number
   }

output "that_number" { value = var.some_number }

2. Reference the module with a number input ~19 digits
```hcl
terraform {
  source = "module/"
}
inputs = {
  some_number = 111111111111111111
}

3. Run a plan. Output:

   10:56:04.786 STDOUT tofu: Initializing the backend...
   10:56:04.788 STDOUT tofu: Initializing provider plugins...
   10:56:04.789 STDOUT tofu: OpenTofu has been successfully initialized!
   10:56:04.789 STDOUT tofu: 
   10:56:04.789 STDOUT tofu: You may now begin working with OpenTofu. Try running "tofu plan" to see
   10:56:04.789 STDOUT tofu: any changes that are required for your infrastructure. All OpenTofu commands
   10:56:04.789 STDOUT tofu: should now work.
   10:56:04.789 STDOUT tofu: If you ever set or change modules or backend configuration for OpenTofu,
   10:56:04.789 STDOUT tofu: rerun this command to reinitialize your working directory. If you forget, other
   10:56:04.789 STDOUT tofu: commands will detect it and remind you to do so if necessary.
   10:56:04.823 STDOUT tofu: Changes to Outputs:
   10:56:04.823 STDOUT tofu:   + that_number = 111111111111111100
   10:56:04.823 STDOUT tofu: You can apply this plan to save these new output values to the OpenTofu
   10:56:04.823 STDOUT tofu: state, without changing any real infrastructure.
   10:56:04.823 STDOUT tofu: 
   10:56:04.823 STDOUT tofu: ─────────────────────────────────────────────────────────────────────────────
   10:56:04.823 STDOUT tofu: Note: You didn't use the -out option to save this plan, so OpenTofu can't
   10:56:04.823 STDOUT tofu: guarantee to take exactly these actions if you run "tofu apply" now.

   Expected behavior

The number is passed to tofu unchanged, and output should match input

Nice to haves

• [ ] Terminal output
• [ ] Screenshots

Versions

• Terragrunt version: terragrunt version v0.68.4
• OpenTofu/Terraform version:OpenTofu v1.8.3 on linux_amd64
• Environment details (Ubuntu 20.04, Windows 10, etc.): below

  linux_amd64
  NAME="Ubuntu"
  VERSION="20.04.6 LTS (Focal Fossa)"

  Additional context

Numbers of this size need to be passed between modules as dependencies for ID references. An example, unique_id's of GCP service accounts.

[e-r-holt]

I also tried storing the value in a var-file, since this issue seems similar, and somebody there suggested var-file values would be a good workaround.

I was not successful with that solution

[e-r-holt]

How neat! I've proven this doesn't happen when you use tofu directly, but it still happens when you store the value in a tofu local.

me@workstation:~/src/test$ tofu plan
var.some_number
  Enter a value: 114229903950591386351

Changes to Outputs:
  + that_number = 114229903950591386351

You can apply this plan to save these new output values to the OpenTofu state, without changing any real infrastructure.