Stacks

A stack in Terragrunt is a collection of related units that can be managed together. Stacks provide a way to:

• Deploy multiple infrastructure components with a single command
• Manage dependencies between units automatically
• Control the blast radius of changes
• Organize infrastructure into logical groups

Terragrunt supports two approaches to defining stacks:

1. Implicit Stacks: Created by organizing units in a directory structure.
2. Explicit Stacks: Defined using terragrunt.stack.hcl files.

Choosing Between Implicit and Explicit Stacks

Use Implicit Stacks When:

• You have a small number of units.
• Each unit is unique and not repeated across environments.
• You don’t mind a high file count.
• You’re just getting started with Terragrunt.
• You need maximum explicitness and transparency.

Use Explicit Stacks When:

• You have multiple environments (dev, staging, prod).
• You want to reuse collections of related infrastructure patterns.
• You have many similar units that differ only in values.
• You want to version collections of infrastructure patterns.
• You’re building infrastructure catalogs or templates.

Tip

Start with implicit stacks to get familiar with the concept, then gradually introduce explicit stacks for reusable patterns as your infrastructure grows.

Examples

For detailed examples, see the Gruntwork Terragrunt Infrastructure Catalog Stack Examples. These have full-featured examples of stacks that deploy real, stateful infrastructure in an AWS account.