teTerragrunt vs. Terraform: A Comparative Analysis of Infrastructure as Code Tools

In the DevOps landscape, numerous tools streamline infrastructure management and deployment. This article delves into two such critical tools: Terraform and Terragrunt.

Terraform is a widely adopted Infrastructure as Code (IaC) tool that enables users to define infrastructure through code rather than manual configuration. It supports automated provisioning, configuration, and deployment of infrastructure across multiple cloud platforms (e.g., AWS, GCP, Azure) as well as other technologies like Kubernetes, Datadog, and VMware.

Terragrunt, by contrast, is a wrapper tool designed to simplify the maintenance and deployment of infrastructure at scale. It provides a streamlined way to manage multiple Terraform modules and deployments, making it easier to handle complex infrastructure setups.

In this article, we will explore each tool individually — examining their purposes, features, and advantages — before comparing their similarities and key differences.

Background

Both Terragrunt and Terraform serve IaC use cases, but they differ fundamentally in their scope and functionality:

• Terraform: A standalone IaC tool that lets you define and manage infrastructure resources and configurations. It uses a declarative language (e.g., HCL, JSON) to describe the desired state of infrastructure and automates the creation, modification, and destruction of resources. Terraform boasts a rich ecosystem and broad support, integrating with various cloud and infrastructure providers.
• Terragrunt: A tool built on top of Terraform to enhance its capabilities. It adds an extra abstraction layer to simplify organizing and managing Terraform code, introducing concepts like modularity, inheritance, and reusability. This allows teams to share and reuse code across multiple Terraform projects, while also offering more robust configuration options and commands for deployment and state management.

Terraform in a Nutshell

Developed by HashiCorp, Terraform is a leading IaC tool whose core function is to enable infrastructure provisioning in a simple, efficient, and declarative manner via reusable code. It automates infrastructure provisioning, configuration, and deployment — whether in cloud environments or on-premises.

One of Terraform’s most valuable features is its cloud-agnosticism: it lets you deploy infrastructure to any cloud environment without learning provider-specific tools. It supports major cloud platforms (Azure, AWS, GCP, VMware) and countless other technologies, making it a versatile choice for multi-cloud strategies.

Another key advantage is Terraform’s ability to manage complex infrastructure. You can define infrastructure as a set of declarative templates, which can be version-controlled, reviewed, and modified over time. This ensures changes are made securely and predictably, maintaining consistency across your infrastructure.

Terraform also benefits from a vast ecosystem of third-party modules and plugins, developed and maintained by a global community of developers and DevOps professionals. These extensions expand Terraform’s functionality and enable integration with hundreds of tools and services.

Note: Newer versions of Terraform are licensed under the BUSL (Business Source License), but all versions prior to 1.5.x remain open-source. OpenTofu — a fork of Terraform 1.5.6 — serves as an open-source alternative, preserving all of Terraform’s popular features while introducing improvements. It is widely regarded as the future of the Terraform ecosystem for teams prioritizing true open-source IaC tools.

Terragrunt in a Nutshell

Developed by Gruntwork, Terragrunt is an open-source wrapper tool for Terraform. Its primary goal is to reduce repetition in Terraform code and simplify code structure, making it easier to manage and maintain at scale. Built around the DRY (Do Not Repeat Yourself) principle, Terragrunt minimizes redundancy by centralizing module management and standardizing remote state handling.

A key advantage of Terragrunt is its ability to manage Terraform configurations across multiple modules. This enables seamless code reuse across infrastructure components, reducing the time and effort required to create and maintain IaC code. Teams can define reusable code as shared modules, which can be leveraged across different projects.

Another critical feature is Terragrunt’s remote state management. It provides a secure way to store and share state files across multiple environments, ensuring infrastructure remains consistent and up-to-date — even as changes are made by different team members or across environments.

Why Use Terragrunt?

With Terraform alone, it is easy to write code for infrastructure limited to a single environment. However, for projects requiring multiple environments (e.g., development, staging, production), Terraform often forces teams to duplicate code with minor environment-specific tweaks — leading to significant redundancy.

For example, consider a typical Terraform project structure for deploying an Azure Storage Account across environments. Folders for int (integration), staging, and prod would each contain identical files: storage-account.tf, variables.tf, and outputs.tf. To deploy to each environment, you would copy-paste code and adjust variables manually—a process prone to error.

With Terraform, deploying to the int environment requires:

1. Navigate to the environment folder: cd /int
2. Preview changes: terraform plan
3. Apply changes: terraform apply

This workflow must be repeated for every environment.

Terragrunt eliminates this redundancy by using .hcl configuration files and centralizing Terraform code in a modules folder:

• .hcl files reference the underlying Terraform modules (stored in modules).
• Environment-specific input values are defined directly in .hcl files, avoiding code duplication.

To deploy the Storage Account to the dev environment with Terragrunt:

1. Navigate to the dev folder: cd /dev
2. Preview changes: terragrunt plan
3. Apply changes: terragrunt apply

Terragrunt also offers the run-all flag to deploy resources across all environments with one command:

1. Navigate to the root Terragrunt folder: cd /terragrunt
2. Deploy to all environments: terragrunt run-all apply

This capability not only reduces code duplication but also streamlines environment configuration management.

Terragrunt is widely adopted for use cases like:

• Managing multiple AWS accounts
• Handling dependencies between Terraform modules
• Automating Kubernetes cluster deployments

Gruntwork’s official documentation outlines additional use cases, and a recommended folder structure is available in this GitHub repository.

Terragrunt vs. Terraform: A Detailed Comparison

While both tools serve IaC needs, their design goals and capabilities differ significantly. Below is a breakdown of their similarities and differences.

Key Similarities

1. Declarative Syntax: Both tools use declarative syntax to define infrastructure. Instead of specifying step-by-step procedures, you describe the desired end state of infrastructure, and the tool handles the implementation.
2. HashiCorp Configuration Language (HCL): Both rely on HCL for configuration — a human-readable language that simplifies defining resources, variables, and outputs.
3. Cloud Provider Support: Both support a wide range of cloud providers (AWS, Azure, GCP, etc.), enabling multi-cloud infrastructure management with a single toolset.
4. Modularity: Both support modularity, allowing teams to reuse code across projects and simplify complex infrastructure management.
5. Active Community: Both tools have large, active user communities that provide support, resources, and examples to help teams adopt best practices.
6. Version-Controlled Infrastructure: Both enable infrastructure management in version-controlled environments, supporting collaboration and change traceability.

Key Differences

CategoryTerraformTerragruntPurposeA standalone IaC tool for building and configuring infrastructure.A wrapper tool built on Terraform to simplify scaling and maintenance.ScopeOperates at the resource level (e.g., creating a single VM or S3 bucket).Operates at the deployment level (manages multiple Terraform modules).ConfigurationUses .tf files for all configurations.Uses .hcl files (in addition to Terraform’s .tf files) for advanced features like dependency management and remote state setup.Dependency ManagementHandles resource-level dependencies via the depends_on keyword (explicit/implicit).Simplifies module-level dependencies, ensuring modules are provisioned in the correct order.Remote State ManagementRequires separate state files for each environment (stored manually or via backends like S3).Centralizes state file management for all environments in a single .hcl file.Project StructureRedundant .tf files for each environment.Eliminates redundancy via a modules folder and environment-specific .hcl files.Command ExecutionRequires switching between environment folders to apply changes.Supports single-command deployment across all environments (via run-all).

Is Terragrunt Better Than Terraform Workspaces?

Terraform includes a workspaces feature to reduce code redundancy and support multi-environment deployments. Each workspace has its own state file, which helps isolate environment-specific configurations.

For example, to create a dev workspace and provision resources with Terraform:

1. Create the workspace: terraform workspace new dev
2. Preview changes: terraform plan
3. Apply changes: terraform apply

This creates a dedicated state file for the dev workspace. However, this workflow must be repeated for every environment (e.g., staging, prod).

While Terraform workspaces are useful for local development and testing, they are not recommended for production-grade deployments. HashiCorp’s official documentation explicitly advises against using workspaces to manage multiple production environments.

Terragrunt offers several advantages over workspaces for production:

• Single-command deployment: Deploy to all environments with terragrunt run-all apply, eliminating the need to switch folders.
• Enhanced visibility: Centralized .hcl files make it easier to track environment-specific configurations.
• Better control: Standardized module management reduces errors and ensures consistency across deployments.

For large-scale, complex infrastructure deployments, Terragrunt is the more reliable choice.

Conclusion

Terraform and Terragrunt are both essential tools in the IaC ecosystem, but they serve distinct roles:

• Terraform is the foundational IaC tool for defining and provisioning infrastructure, offering cloud-agnosticism and a rich ecosystem.
• Terragrunt enhances Terraform by simplifying multi-module management, reducing code redundancy, and streamlining multi-environment deployments.

While Terraform workspaces work for small-scale or local use cases, Terragrunt is superior for production-grade, complex infrastructure — thanks to its centralized configuration, module dependency management, and single-command deployment capabilities.

For teams looking to scale their IaC practices, combining Terraform (for resource provisioning) with Terragrunt (for governance and scalability) is a powerful strategy.

About Me

My technical insights and resources are centralized on the following platforms, focusing on cloud-native, DevOps, Kubernetes, AIOps, GenAI,and related technologies:

• Personal Website: https://redhatxl.github.io (a hub for my technical notes, tutorials, and project updates)，https://kaliarch-web.pages.dev/
• GitHub: https://github.com/redhatxl (hosts representative projects like awesome-kubernetes-notes, kubectl-img, and k8s-prometheus-grafana)
• Certification Profile: https://www.credly.com/users/redhatxl (showcases authoritative certifications including AWS Certified DevOps Professional, Azure Solutions Architect Expert, and HashiCorp Terraform Certified Associate)