Terragrunt - Simplify and Scale Your Infrastructure with Ease

In the world of infrastructure as code (IaC), managing complex infrastructure efficiently and consistently can be a daunting task. However, with the advent of tools like Terragrunt, this process has become significantly easier. Terragrunt, an open-source tool developed by Gruntwork, is designed to enhance and simplify the usage of Terraform, an industry-leading IaC tool. In this blog post, we will explore the benefits of Terragrunt and provide examples of how it can streamline your infrastructure management workflow.

What is Terragrunt?

Terragrunt is a thin wrapper tool that extends the functionality of Terraform, providing additional features and solving common challenges faced when working with Terraform code. It acts as a powerful orchestration layer, allowing for seamless configuration and deployment management of multiple Terraform modules, remote state storage, and cross-account deployments. Terragrunt simplifies the management of complex infrastructure environments and helps teams adhere to best practices.

Benefits of Terragrunt

Modular Configuration

Terragrunt introduces a modular approach to Terraform configuration, allowing you to organize and reuse code effectively. It enables the creation of reusable modules that encapsulate infrastructure components, making it easier to manage and maintain configurations across multiple environments.

DRY (Don’t Repeat Yourself)

Terragrunt promotes code reusability and reduces duplication by enabling the extraction of common configuration elements into shared modules. This approach ensures consistency and reduces the likelihood of errors or inconsistencies across deployments.

Remote State Management

Terragrunt simplifies the management of Terraform’s remote state. It supports backend configurations like Amazon S3, Azure Blob Storage, or HashiCorp Consul, which provide a centralized and version-controlled store for Terraform state files. This feature helps maintain state integrity and enables seamless collaboration among team members.

Dependency Management

With Terragrunt, you can define and manage dependencies between different Terraform modules. This feature ensures that dependent modules are deployed in the correct order, avoiding potential resource conflicts and increasing the reliability of your deployments.

Encrypted Variables

Terragrunt offers a built-in encryption feature that allows you to securely store sensitive information such as access keys, secrets, or API tokens. By encrypting variables, you can protect sensitive data and ensure secure deployments without exposing confidential information in your configuration files.

Example

Suppose you are working on a project that requires deploying a web application to different environments: development, staging, and production. Each environment requires its own set of resources, such as a virtual network, load balancer, and database.

To start, you would create a folder structure for your project:

my-project/
├── environments/
│   ├── dev/
│   ├── stage/
│   └── prod/
├── modules/
└── terragrunt.hcl

Define Terraform Modules:

In the modules/ directory, you would create reusable Terraform modules representing the infrastructure components required by your web application. For example, you might have modules for a virtual network, a load balancer, and a database.

Configure Environments:

In the environments/ directory, you would create separate folders for each environment (dev/, stage/, and prod/). Within each environment folder, you would define a terragrunt.hcl file to configure the environment-specific settings.

For example, let’s look at the dev/terragrunt.hcl file:

terraform {
  source = "../modules"
}

inputs = {
  environment = "dev"
  vpc_name    = "my-dev-vpc"
  lb_name     = "dev-load-balancer"
  db_name     = "dev-database"
}

Here, we define the source as ../modules, indicating that the modules are located in the parent directory. We also specify environment-specific input variables, such as the environment name, VPC name, load balancer name, and database name.

Similarly, you would create stage/terragrunt.hcl and prod/terragrunt.hcl files with the appropriate input variable values for each environment.

Terragrunt Configuration:

In the root of your project, you would have a terragrunt.hcl file that configures Terragrunt and defines common settings shared across all environments.

include {
  path = "environments/*"
}

In this example, we use the include block to specify a wildcard path pattern (environments/*) to include all environment-specific configurations. This allows Terragrunt to automatically apply the configurations for each environment when executed.

Deploying Infrastructure: To deploy the infrastructure for a specific environment, navigate to the respective environment directory and run Terragrunt commands.

For instance, to deploy the development environment, you would go to the dev/ directory and execute Terragrunt commands:

cd environments/dev && \
terragrunt init && \
terragrunt plan && \
terragrunt apply

Terragrunt will handle the initialization, planning, and applying of Terraform configurations using the specified input variables. It will also manage the state files for each environment, ensuring isolation and consistent deployments.

You can repeat the same process for the staging and production environments by navigating to the corresponding directories (environments/stage and environments/prod) and running the Terragrunt commands.

Conclusion

By leveraging Terragrunt, you can easily manage and deploy infrastructure across different environments while maintaining consistency and reducing duplication. Terragrunt’s modular approach, remote state management, and dependency handling simplify the management of complex infrastructure deployments.