How to get a relative path of terragrunt.hcl in an AWS resource's tag?

Question

How can I tag each AWS resource with a relative path of its source/terragrunt.hcl file? Ideally, the solution, if it exists, would also work with a locally/relatively referenced modules (rather than only modules from a git repo).

# In root terragrunt.hcl
locals {
  # ...
  aws_default_tags = jsonencode({  # This is line 48 in the error below.
    ManagedBy = "Terraform"
    TerraformBasePath = path.cwd  # What is a (working) equivalent of this?
  )}
}

generate "provider" {
  # ...
  contents  = <<EOF
provider "aws" {
  # ...
  default_tags {
    tags = jsondecode(<<INNEREOF
${local.aws_default_tags}
INNEREOF
)
  }

}
EOF
}

The error on terragrunt apply, with the root terragrunt.hcl as above:

> terragrunt apply 
ERRO[0000] Not all locals could be evaluated:           
ERRO[0000]      - aws_default_tags [REASON: Can't evaluate expression at 
/project/terragrunt.hcl:48,22-60,5: 
you can only reference other local variables here, 
but it looks like you're referencing something else (path is not defined)] 
ERRO[0000] Could not evaluate all locals in block.      
ERRO[0000] Unable to determine underlying exit code, so Terragrunt
will exit with error code 1

@MarkoE I've added the error. Obviously, one can't use `path` (`"path is not defined"`) but I'm not sure _how then_ to get the .hcl's relative path into an AWS tag. — VanillaDonuts, Oct 18 '22 at 13:38
Does this help: https://terragrunt.gruntwork.io/docs/reference/built-in-functions/#get_terragrunt_dir? — Marko E, Oct 18 '22 at 13:51

score 0 · Accepted Answer · answered Oct 18 '22 at 14:32

Got the relative path added as a tag, by simplifying the 1st snippet in the question:

# In root terragrunt.hcl
locals {
  # ...
# terraform-git-repo = "infrastructure"  # For future use in CD pipeline.
  terraform-git-repo = "/local/path/infra"
}

generate "provider" {
  # ...
  contents  = <<EOF
provider "aws" {
  # ...
  default_tags {
    tags = {
      Terraform-base-path = replace(replace(path.cwd, "${local.terraform-git-repo}", ""), "/.terragrunt-cache/.*/", "")
    }
  }

}
EOF
}

The nested replace functions could use some simplification.

How to get a relative path of terragrunt.hcl in an AWS resource's tag?

1 Answers1