Dependency inversion with modules in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is dependency inversion in Terraform modules?

Dependency inversion means designing modules so that higher-level modules do not depend on lower-level modules directly. Instead, they depend on abstractions or inputs, allowing flexibility and easier changes.

beginner

Why use dependency inversion with Terraform modules?

It helps keep modules reusable and independent. Changes in one module won't break others because dependencies are managed through inputs and outputs, not hard-coded references.

intermediate

How do Terraform modules communicate dependencies without tight coupling?

Modules communicate using input variables and output values. One module outputs data, and another module receives it as input, avoiding direct internal references.

intermediate

Example: How to invert dependency between a network module and an instance module?

The network module outputs subnet IDs. The instance module takes subnet IDs as input variables. The root module connects them by passing outputs to inputs, not by the instance module calling the network module directly.

advanced

What is a benefit of dependency inversion when scaling Terraform projects?

It allows teams to work on modules independently, reduces errors from tight coupling, and makes it easier to replace or upgrade modules without affecting the whole infrastructure.

What does dependency inversion in Terraform modules primarily promote?

A Loose coupling between modules

B Direct module calls inside other modules

C Hard-coded resource IDs

D Ignoring module outputs

Dependency inversion promotes loose coupling by using inputs and outputs instead of direct references.

How do Terraform modules share data without tight dependency?

A Using output values and input variables

B By importing each other's code

C By hardcoding resource names

D By running scripts inside modules

Modules share data through outputs and inputs, which keeps them independent.

Which Terraform component connects module outputs to inputs?

A Backend

B Provider

C Resource block

D Root module

The root module orchestrates passing outputs from one module as inputs to another.

What is a risk of not using dependency inversion in Terraform modules?

A Modules automatically update

B Modules run faster

C Modules become tightly coupled and hard to maintain

D Modules use fewer variables

Without dependency inversion, modules depend directly on each other, making maintenance difficult.

Which practice aligns with dependency inversion in Terraform?

A Hardcoding subnet IDs inside instance module

B Passing subnet IDs as input variables to instance module

C Calling network module inside instance module

D Ignoring module outputs

Passing subnet IDs as inputs keeps modules independent and flexible.

Explain how dependency inversion improves Terraform module design.

Think about how modules avoid direct references and rely on data passed in.

Describe a simple example of dependency inversion between two Terraform modules.

Consider network and instance modules sharing subnet IDs.