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Terragrunt HCL Format (hclfmt) enforces a consistent style for Terragrunt’s HashiCorp Configuration Language (HCL) files. Built on top of terraform fmt, it applies Terraform’s formatting conventions while understanding Terragrunt’s hierarchical configuration structure. Using terragrunt hclfmt helps teams maintain clean, readable code and minimize version-control noise.
The image describes the purpose of "Terragrunt hclfmt," highlighting its use for formatting HCL files, enforcing consistent formatting, being equivalent to 'terraform fmt,' and maintaining a clean and readable codebase.

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Integration and Workflow

Integrate terragrunt hclfmt into your development lifecycle to automate formatting:
  • Embed in Git pre-commit hooks to catch style issues before code review.
  • Run in CI/CD pipelines to enforce formatting across all branches.
  • Leverage the underlying terraform fmt compatibility for seamless adoption.
The image illustrates the integration of Terragrunt hclfmt with Terragrunt.hcl, highlighting its connection with Terraform.
Best Practices:
  • Add terragrunt hclfmt to your .pre-commit-config.yaml so developers never miss a formatting step.
  • Include formatting checks in your pipeline as a gating job.
  • Keep your Terragrunt modules consistent by running hclfmt after merging feature branches.
The image is about automating the formatting process using CI/CD pipelines and Git pre-commit hooks, with a "Best Practices" button at the bottom.

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Core Benefits

Using terragrunt hclfmt delivers:
BenefitDescription
Consistent FormattingUniform HCL style for Terragrunt and Terraform files.
Easier CollaborationReduces discussions over indentation and layout.
Cleaner DiffsRemoves non-functional changes from version control.
The image highlights the benefits of "Terragrunt hclfmt," including improved code readability, easier collaboration, and reduced version control noise.

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Example Usage

Here’s how to format a simple terragrunt.hcl that defines a VPC module with inputs for name and cidr: Unformatted terragrunt.hcl: 
terraform {
  source = "tfr://terraform-aws-modules/vpc/aws//?version=5.8.1"
}

inputs = {
  name = "Kodekloud-VPC-2"
  cidr = "10.0.0.0/16"
}
Run the formatter: 
cd ~/workspace
terragrunt hclfmt
Terminal output: 
INFO[0000] /config/workspace/terragrunt.hcl was updated
After formatting, the file adheres to style guidelines: 
terraform {
  source = "tfr://terraform-aws-modules/vpc/aws//?version=5.8.1"
}

inputs = {
  name = "Kodekloud-VPC-2"
  cidr = "10.0.0.0/16"
}
This workflow ensures that every Terragrunt HCL file in your repository remains consistent, reducing merge conflicts and speeding up code reviews.
Integrating terragrunt hclfmt early in your CI/CD process saves time and enforces standards across teams.
Always run terragrunt hclfmt before committing changes. Unformatted HCL may cause pipeline failures or inconsistent diffs.

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