allow import `terraform` block passing locals from child module

[chell0veck]

Describe the enhancement

I'm looking the way to move following section next to root.hcl and import that across all child files.

terraform {
  source = (
    include.root.locals.tf_local_deploy ?
    format(include.root.locals.tf_local_ref,
      include.root.locals.tfmodules_name, local.module_name

    ) :
    format(
      include.root.locals.tf_remote_ref,
      include.root.locals.tfmodules_name, local.module_name, include.root.locals.tfmodules_version
    )
  )
}

Additional context

Here is a common pattern we use across 100-ish modules.

include "root" {
  path   = find_in_parent_folders("root.hcl")
  expose = true
}

include "region" {
  path   = find_in_parent_folders("region.hcl")
  expose = true
}

terraform {
  source = (
    include.root.locals.tf_local_deploy ?
    format(include.root.locals.tf_local_ref,
      include.root.locals.tfmodules_name, local.module_name

    ) :
    format(
      include.root.locals.tf_remote_ref,
      include.root.locals.tfmodules_name, local.module_name, include.root.locals.tfmodules_version
    )
  )
}

locals {
  module_name = "aws-vpc-endpoint"
}

inputs = {
...
}

following way to optimise the block does not allow to pass locals from child module and only works if content of terraform.hcl hardcoded.

include "terraform" {
  path   = find_in_parent_folders("terraform.hcl")
}

Things you might want to address include:

Changing around this block would definitely save a lots of redundant code and will allow to maintain huge projects easier and make code more DRY.

[FlorinAndrei]

Yeah, I wish there was a "dumb include" in Terragrunt, that would just grab code from somewhere else, without interpreting it in place, insert it in the current terragrunt.hcl and now begin to interpolate and interpret it.

That would be great.