Demo Sourcing a Module From the Terraform Registry

In this guide, we’ll demonstrate how to source the same S3 bucket module from the Terraform Registry using Terragrunt. Instead of pulling the module from GitHub, we switch to the tfr:/// prefix and pin a specific version. This approach simplifies version management and leverages the official Terraform Registry distribution.

Why Use the Terraform Registry?

terragrunt.hcl Configuration

Create or update your terragrunt.hcl file with the registry source and input variables:

# terragrunt.hcl
terraform {
  source = "tfr:///terraform-aws-modules/s3-bucket/aws?version=4.1.2"
}

inputs = {
  bucket = "my-unique-bucket-name"
  acl    = "private"

  public_access_block = {
    block_public_acls       = true
    block_public_policy     = true
    ignore_public_acls      = true
    restrict_public_buckets = true
  }
}

The syntax breakdown:

• tfr:/// — Registry prefix (two slashes for delimiter + one slash to start address).
• namespace/module_name/provider — Module path on the Terraform Registry.
• ?version=x.y.z — Query parameter to lock the module version.

Initialize and Apply with Terragrunt

Run the following commands to download the module and provision your S3 bucket:

$ terragrunt init
[terragrunt]  INFO: Downloading module...
...

$ terragrunt apply --auto-approve
...
Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Verify the S3 Bucket

Use the AWS CLI to confirm that your bucket exists:

$ aws s3 ls
2023-08-15 12:34:56 my-unique-bucket-name

Links and References

• Terragrunt Documentation
• Terraform Registry: S3 Bucket Module
• AWS CLI S3 Commands