Terraform Best Practices for Your Infrastructure as Code (IaC) Workflow

Terraform is a powerful tool for managing infrastructure as code (IaC), but to maximize its effectiveness and maintainability, it’s important to follow established best practices. Below are key recommendations to help you write better, more secure, and more reliable Terraform code.

1. Use Remote State

Always store your Terraform state in a remote, shared location (like AWS S3, Google Cloud Storage, or Terraform Cloud). This supports collaboration, provides state locking to prevent conflicts, and enables backups for disaster recovery.

2. Leverage Modules

Build and use modules to encapsulate and reuse infrastructure components.

Use community modules when possible, but review their code to understand what they do.

Document modules thoroughly, specifying inputs and outputs for clarity and ease of use.

3. Structure Your Project for Maintainability

Keep your code organized: Use separate files for variables (variables.tf), outputs (outputs.tf), and resources (main.tf).

Break down large projects into reusable, well-defined modules.

Consider monorepo vs. polyrepo strategies based on your team size and project complexity.

4. Secure Your Terraform Workflow

Implement a secrets management strategy (e.g., use environment variables, HashiCorp Vault, or cloud-native secret managers).

Automate security scans (e.g., with checkov, tflint, or tfsec) and enforce policy as code (e.g., OPA, Sentinel).

Restrict access to production apply operations—only allow CI/CD pipelines or service accounts to apply changes in production.

5. Automate and Test

Automate linting and validation (terraform fmt, terraform validate, tflint).

Test your Terraform code using tools like Terratest or InSpec.

Enforce peer review on Terraform plans before merging or applying changes.

6. Follow Style and Structure Guidelines

Use consistent naming conventions for resources and variables.

Tag resources for easier management and tracking.

Limit expression complexity—use local values to break up complex logic.

Use the lifecycle block to protect critical resources (e.g., prevent accidental deletion).

7. Manage State and Configuration Carefully

Avoid manual state changes—treat state as immutable and always use versioning/backups.

Use workspaces or stacks to manage multiple environments (dev, staging, prod).

Be cautious with terraform_remote_state—it exposes the entire state, so consider using parameter stores or Consul for sensitive data.

8. Documentation and Collaboration

Document your code and modules with clear comments and READMEs.

Share reusable modules across your organization to standardize infrastructure.

9. Continuous Improvement

Refactor and review your Terraform code regularly.

Stay updated with new features and community best practices.

Example Project Structure

project/

├── modules/

│ └── network/

│ ├── main.tf

│ ├── variables.tf

│ └── outputs.tf

├── environments/

│ ├── dev/

│ │ ├── main.tf

│ │ ├── variables.tf

│ │ └── terraform.tfvars

│ └── prod/

│ ├── main.tf

│ ├── variables.tf

│ └── terraform.tfvars

├── main.tf

├── variables.tf

└── outputs.tf

Final Thoughts

Adopting these Terraform best practices will help you build robust, scalable, and maintainable infrastructure as code. Whether you’re a beginner or an advanced user, focusing on organization, security, automation, and documentation will set you up for success