Dependabot does not support Terragrunt's `tfr://` protocol for private Terraform registries

[salsiy]

Is there an existing issue for this?

• I have searched the existing issues

Package ecosystem

terraform

Package manager version

Terragrunt is used as a wrapper

Language version

Terragrunt v0.85.1 / Terraform v1.9.0

Manifest location and content before the Dependabot update

File:** live/dev-account/eu-west-1/nlb/terragrunt.hcl

terraform {
  source = "tfr://registry.example.com/namespace/module/provider?version=1.0.0"
}

inputs = {
  # ... configuration
}

dependabot.yml content

version: 2
registries:
  private-registry:
    type: terraform-registry
    url: https://registry.example.com
    token: ${{ secrets.REGISTRY_TOKEN }}

updates:
  - package-ecosystem: "terraform"
    directories:
      - "/live/dev-account/*/*"
    registries:
      - private-registry
    schedule:
      interval: "daily"

Updated dependency

N/A - Dependabot fails to parse the source before it can detect any dependencies

What you expected to see, versus what you actually saw

Expected:

• Dependabot should successfully parse Terragrunt configurations using the tfr:// protocol
• Dependabot should detect the module version and check for updates from the configured private Terraform registry
• Dependabot should create PRs when newer versions are available

Actual:
Dependabot fails with the following error:

dependency_file_not_evaluatable | {
  "message": "Invalid registry source specified: 'tfr://registry.example.com/namespace/module/provider?version=1.0.0'"
}

Native package manager behavior

terragrunt init
terragrunt plan

Terragrunt successfully:

• Parses the tfr:// source URL
• Connects to the private registry
• Downloads the module
• Executes Terraform commands without issues

Images of the diff or a link to the PR, issue, or logs

Error from Dependabot logs:

updater | 2026/01/02 17:15:41 INFO Results:
Dependabot encountered '1' error(s) during execution

+---------------------------------------------------------------------------------------------------------------+
|                                    Errors                                                                     |
+---------------------------------+-----------------------------------------------------------------------------+
| Type                            | Details                                                                     |
+---------------------------------+-----------------------------------------------------------------------------+
| dependency_file_not_evaluatable | "Invalid registry source specified: 'tfr://registry.example.com/...'"      |
+---------------------------------+-----------------------------------------------------------------------------+

---

Smallest manifest that reproduces the issue

terragrunt.hcl:

terraform {
  source = "tfr://registry.example.com/namespace/module/provider?version=1.0.0"
}