Modules

Modules are the primary way to organise, reuse, and share Terraform configuration. A module is simply a directory containing .tf files. This lesson covers creating modules, using module sources, the Terraform Registry, and module composition patterns.

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What is a Module?

Every Terraform configuration is a module:

• Root module — the directory where you run terraform apply
• Child module — a module called from another module using a module block

project/
├── main.tf              ← root module
├── variables.tf
├── outputs.tf
└── modules/
    └── network/         ← child module
        ├── main.tf
        ├── variables.tf
        └── outputs.tf

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Why Use Modules?

Benefit	Description
Reusability	Write once, use across multiple projects
Organisation	Group related resources into logical units
Encapsulation	Hide implementation details behind a clean interface
Consistency	Enforce standards across your organisation
Testability	Test modules independently

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Creating a Module

Module Structure

A module has the same file structure as any Terraform configuration: