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Terragrunt supporting files let you centralize environment-specific and global settings, promoting consistency and reusability across Terraform configurations. By defining variables in dedicated HCL or YAML files, you tailor deployments to specific accounts, regions, and environments without duplication.

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Core Supporting Files

FilePurposeTypical Contents
account.hclAccount-specific detailsaccount_id, account_name
region.hclRegion-specific parametersAWS regions like us-east-1, geolocation
env.hclEnvironment-specific valuesproject_name, tag conventions, parameters
common.hclGlobal defaults shared across all environmentsCompany tags, naming conventions
Supporting files can be written in HCL or YAML. Use HCL for native Terraform/Terragrunt integration, or YAML if you prefer readability and tooling compatibility.
The image shows a diagram of supporting files with four categories: account.hcl, region.hcl, env.hcl, and common.hcl, each associated with specific information like account ID, region, project details, and global tags.
Place these files alongside your Terraform modules: 
live
├── account.hcl
├── region.hcl
├── env.hcl
├── common.hcl
└── modules
    └── app
        └── terragrunt.hcl

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Example Configurations

# example-account.hcl
locals {
  account_id   = "123456789012"
  account_name = "production-account"
}

# example-common.yaml
globals:
  company_name: "AcmeCorp"
  tags:
    - "owner:infra"
    - "compliance:internal"

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Benefits of Supporting Files

  • Reusability: Import shared settings across multiple modules and environments.
  • Maintainability: Update a value in one file and have it propagate everywhere.
  • Consistency: Enforce standard tagging, naming conventions, and defaults.
Avoid committing sensitive data (like credentials or secrets) directly in these files. Use tools like Vault or encrypt secrets with sops.

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References

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