Passing Outputs Between Terraform Modules with Terragrunt

As Terraform projects start to grow, it's important to organize infrastructure components into separate Terraform state files. This greatly reduces the blast radius for changes made to the infrastructure. This strategy is a popular concept within the Terraform community and is also referred to as "Terraservices." The infrastructure that frequently changes like EC2, ECS, or EKS services should stay separate from infrastructure that rarely changes, like VPC configurations. Also, sensitive services like RDS should have their state file. You don't want to be resizing an EC2 instance in the same Terraform configuration that contains code for the MYSQL database. Splitting up components can become very hard to manage with Terraform alone, which is why Terragrunt becomes an important tool when managing infrastructure that has been split up into Terraservices.

In this lab, you will use Terragrunt to split up an environment into separate states and pass data between each component.

Learning objectives

Upon completion of this lab, you will be able to:

• Understand how to deploy Terraform resources with Terragrunt
• Learn how to pass data between modules using Terragrunt
• Understand the concept of reducing the blast radius with separate Terraform states

Intended audience

This lab is intended for:

• Individuals familiar with using Terraform and how to deploy resources
• Individuals interested in learning how to use Terragrunt to increase Terraform's effectiveness
• Enterprises looking to scale their Terraform codebase

Prerequisites

You should be familiar with:

• Cloud Services
• DevOps
• Basic understanding of Terraform modules and variables
• Basic understanding of Terragrunt and keeping remote state DRY

The following course and lab can be used to fulfill the prerequisites:

• Introduction to DevOps
• Creating Reusable Infrastructure with Terraform Modules
• Using Terraform Remote State
• Keeping Terraform Remote State DRY with Terragrunt

Updates

January 9th, 2024 - Lab updated to utilize CodeTour IDE

June 17th, 2021 - Updated the instance type created by Terraform