Terraform Code Hygiene: Automate Quality Checks with TFLint and FMT

Infrastructure as Code (IaC) has revolutionized cloud provisioning, with Terraform emerging as a dominant tool for managing cloud infrastructure. However, maintaining code quality and consistency becomes crucial as teams grow and codebases expand. This is where automated quality checks with TFLint and Terraform FMT come into play.

In this guide, you'll learn how to integrate TFLint and terraform fmt into your development pipeline to enforce Terraform code standards, reduce human error, and increase productivity.

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Why Code Hygiene Matters in Terraform

Terraform configurations can become large and complex over time. Without consistent formatting and proper linting:

• Syntax errors can go unnoticed.
  
  

• Inefficient or deprecated patterns may be used.
  
  

• Collaborative development becomes error-prone.
  
  

Automating linting and formatting ensures your Terraform code remains readable, maintainable, and production-ready.

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TFLint: Terraform Linter for Best Practices

What Is TFLint?

TFLint is a powerful linter specifically designed for Terraform. It detects potential errors, enforces best practices, and supports plugin-based rule expansion for providers like AWS, Azure, and Google Cloud.

Key Features

• Detect unused declarations
  
  

• Catch typos in provider-specific attributes.
  
  

• Enforce naming conventions and security best practices.
  
  

• Integrate with CI/CD pipeline.s
  
  

Installation

brew install tflint  # For macOS

# Or use:

curl -s https://raw.githubusercontent.com/terraform-linters/tflint/master/install_linux.sh | bash

Usage

Run TFLint in your project root:

tflint

To use provider-specific rules:

tflint --init

Customize rules with a .tflint.hcl config file.

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terraform fmt: Enforce Standard Formatting

Terraform includes a built-in formatter terraform fmt, which automatically aligns code to canonical style.

Benefits

• Prevents style-related code review debates
  
  

• Ensures team-wide consistency
  
  

• Easy to automate as a pre-commit hook or CI/CD step
  
  

Usage

Format all Terraform files in the current directory:

terraform fmt

To format recursively:

terraform fmt -recursive

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Automating with GitHub Actions

Here's a sample GitHub Actions workflow to enforce TFLint and terraform fmt:

name: Terraform Lint & Format

on: [push, pull_request]

jobs:

  lint-and-format:

    runs-on: ubuntu-latest

    steps:

    - name: Checkout repo

      uses: actions/checkout@v2

    - name: Set up Terraform

      uses: hashicorp/setup-terraform@v2

    - name: Install TFLint

      run: |

        curl -s https://raw.githubusercontent.com/terraform-linters/tflint/master/install_linux.sh | bash

    - name: Run TFLint

      run: tflint --init && tflint

    - name: Check terraform fmt

      run: terraform fmt -check -recursive

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Optional: Add Pre-Commit Hooks

To enforce checks before code even hits the repository:

Install pre-commit.

Create a .pre-commit-config.yaml:

repos:

  - repo: https://github.com/antonbabenko/pre-commit-terraform

    rev: v1.70.0

    hooks:

      - id: terraform_fmt

      - id: terraform_tflint

Run:

pre-commit install

Now, every git commit will automatically format and lint your code.

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Final Thoughts

Maintaining clean and consistent Terraform code is vital for infrastructure reliability and team efficiency. Automating quality checks using TFLint and Terraform FMT helps enforce best practices, improve collaboration, and reduce costly production bugs.

Embrace code hygiene—your future self (and team) will thank you.