By Sebastian Stadil —

Terraform Module Creation with Cookiecutter

Terraform has become a de facto standard for Infrastructure as Code (IaC), allowing teams to define and manage infrastructure with code. A key best practice in Terraform is the use of modules—reusable components that encapsulate sets of resources. While modules promote consistency and reduce boilerplate, creating high-quality, standardized modules can be a challenge. This is where tools like Cookiecutter, and specifically the TerraformInDepth/terraform-module-cookiecutter, come into play.

The Challenge: Consistent Module Development

As organizations scale their Terraform usage, the number of custom modules often grows. Without a standardized approach, this can lead to:

  • Inconsistent structures: Different developers might organize files and directories differently.
  • Varying quality: Lack of automated checks for linting, security, and testing.
  • Increased maintenance overhead: Non-standard modules are harder to understand, update, and share.

These issues can negate many of the benefits that modules are intended to provide.

Enter Cookiecutter for Terraform Modules

Cookiecutter is a command-line utility that creates projects from project templates. The TerraformInDepth/terraform-module-cookiecutter is a specialized template designed to generate Terraform modules incorporating a comprehensive set of best practices from the ground up. Associated with the Terraform in Depth book, this template aims to codify expert knowledge into a practical tool.

Key Features and Integrated Tooling

The TerraformInDepth/terraform-module-cookiecutter isn't just about a directory structure; it bundles a suite of tools and configurations to enforce quality, security, and consistency:

Feature Category

Tool(s)

Purpose

Security Scanning

Checkov, Trivy

Identify security vulnerabilities and misconfigurations in IaC.

Quality Control

TFLint

Lint Terraform code for errors, best practices, and potential issues.

Formatting & Validation

Terraform/OpenTofu fmt & validate

Ensure consistent code style and syntactic correctness.

CI Integration

GitHub Actions Workflows

Automate checks (linting, scanning, testing) on code changes.

Git Hooks

Pre-Commit Framework

Run local checks before commits to catch issues early.

Version Management

tenv

Manage Terraform and OpenTofu versions for consistency.

Testing

Terratest, Terraform Testing Framework

Provide frameworks for unit and integration tests for the module.

This integrated approach helps "shift left" the detection of issues, ensuring modules are built to a high standard from their inception.

Generating Your First Standardized Module

Getting started is straightforward. First, ensure you have Python and Cookiecutter installed:

# Example using pip
pip install cookiecutter

Then, run the cookiecutter command to generate a module from the template:

cookiecutter gh:TerraformInDepth/terraform-module-cookiecutter

You'll be prompted for details like module_name, terraform_provider, github_owner, and versions for Go, Terraform, and OpenTofu. These inputs customize the generated module, which will include:

  • Standard Terraform files (main.tf, variables.tf, outputs.tf)
  • An examples/ directory
  • A tests/ directory (with Terratest and native test setups)
  • .github/workflows/ for CI
  • .pre-commit-config.yaml
  • A Makefile for common tasks
  • Version management files (e.g., .terraform-version)

Activating Best Practices Day-to-Day

Once your module is generated, you can immediately benefit from the integrated tooling.

  1. CI Pipeline: Pushing your module to a GitHub repository will trigger the pre-configured GitHub Actions, automating validation, linting, security scanning, and testing.

Manual Checks: You can also run tools manually, often via Makefile targets provided in the generated module:

# Example: Run TFLint (actual command might be `make lint` or similar)
tflint --recursive

# Example: Run Checkov (actual command might be `make scan-security` or similar)
checkov -d .

Install Pre-Commit Hooks: Navigate to your new module directory and run:

pre-commit install

This will run configured checks (like terraform fmt, tflint, checkov) automatically before each commit.

The Bigger Picture: Managing Modules at Scale

Creating standardized, high-quality modules with tools like the TerraformInDepth/terraform-module-cookiecutter is a significant step forward. However, as your library of modules grows and they are consumed by multiple teams and projects, managing them effectively becomes the next challenge. This is where platforms like Scalr can provide immense value.

Scalr helps organizations manage their IaC journey by offering:

  • A centralized module registry: Making it easy to discover, version, and share your standardized modules.
  • Policy enforcement (OPA): Ensuring that modules are used in compliance with organizational standards and security policies.
  • Environment management and drift detection: Providing visibility and control over how and where your infrastructure (defined by these modules) is deployed.
  • Collaboration and RBAC: Facilitating teamwork and secure access to infrastructure configurations.

By combining standardized module creation with a robust IaC management platform, organizations can truly scale their infrastructure automation efforts reliably and securely.

Conclusion

The TerraformInDepth/terraform-module-cookiecutter provides an excellent foundation for building robust, secure, and maintainable Terraform modules. It accelerates development by embedding best practices and automation directly into the module creation process. While such templates address the "how-to-build" aspect, pairing them with a comprehensive management platform like Scalr addresses the "how-to-govern-and-scale" aspect, leading to a more mature and efficient Infrastructure as Code practice.