Root module concept in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the root module in Terraform?

The root module is the main folder where you run Terraform commands. It contains the primary configuration files that define your infrastructure.

beginner

How does Terraform find the root module?

Terraform looks in the current working directory where you run the commands. This directory is the root module.

intermediate

Can the root module call other modules?

Yes, the root module can include other modules to organize and reuse infrastructure code.

beginner

Why is the root module important in Terraform?

It acts like the main blueprint for your infrastructure. All Terraform commands start here, and it controls how other modules fit together.

beginner

What files are typically found in the root module?

Files like main.tf, variables.tf, outputs.tf, and terraform.tfstate are usually in the root module folder.

Where does Terraform look for the root module?

A In the current working directory

B In the cloud provider's console

C In a hidden system folder

D In the user's home directory

Terraform uses the current working directory as the root module location.

What is the main role of the root module?

A To define the main infrastructure configuration

B To store Terraform state files only

C To manage cloud provider credentials

D To run Terraform commands remotely

The root module defines the main infrastructure setup and configuration.

Can the root module include other modules?

A Only if they are in the same folder

B No, modules are separate and cannot be linked

C Yes, to organize and reuse code

D Only if they are from the Terraform registry

The root module can call other modules to organize and reuse infrastructure code.

Which file is NOT typically part of the root module?

A main.tf

B index.html

C variables.tf

D outputs.tf

index.html is not related to Terraform configuration files.

What happens if you run Terraform commands outside the root module directory?

A Terraform will automatically find the root module elsewhere

B Terraform will run but ignore all modules

C Terraform will create a new root module automatically

D Terraform will fail because it can't find configuration files

Terraform needs to run in the root module directory to find configuration files.

Explain what the root module is and why it is important in Terraform.

Think of the root module as the main folder where Terraform looks first.

Describe how the root module interacts with other modules in a Terraform project.

Consider the root module as the main blueprint that includes smaller blueprints.

Practice

1. What is the root module in Terraform?

easy

A. A Terraform provider plugin

B. A special Terraform resource type

C. A remote backend configuration

D. The main folder where Terraform commands are run and resources are defined

Solution

1. Step 1: Understand the root module role

   The root module is the main folder where you write your Terraform code and run commands.

2. Step 2: Differentiate from other concepts

   It is not a resource type, backend, or provider plugin but the main working directory.

3. Final Answer:

   The main folder where Terraform commands are run and resources are defined -> Option D

4. Quick Check:

   Root module = main Terraform folder [OK]

Hint: Root module is your main Terraform folder [OK]

Common Mistakes:

• Confusing root module with provider or backend
• Thinking root module is a resource type
• Assuming root module is a plugin

2. Which command must be run inside the root module folder to initialize Terraform?

easy

A. terraform apply

B. terraform init

C. terraform plan

D. terraform validate

Solution

1. Step 1: Identify the initialization command

   terraform init sets up the working directory by downloading providers and preparing the backend.

2. Step 2: Confirm command location

   This command must be run inside the root module folder where the Terraform files exist.

3. Final Answer:

   terraform init -> Option B

4. Quick Check:

   Initialize Terraform = terraform init [OK]

Hint: Use 'terraform init' to start in root module folder [OK]

Common Mistakes:

• Running terraform apply before init
• Confusing init with plan or validate
• Running commands outside root module folder

3. Given this root module folder structure:

root-module/
  main.tf
  variables.tf
  modules/
    network/
      main.tf

Which statement is true about the root module?

medium

A. It can call the network module inside the modules folder

B. It must be empty to work correctly

C. It cannot use modules from subfolders

D. It only contains variables and no resources

Solution

1. Step 1: Understand root module and submodules

   The root module can call other modules located in subfolders like modules/network.

2. Step 2: Evaluate options

   It can call the network module inside the modules folder correctly states the root module can call the network module. Other options are false.

3. Final Answer:

   It can call the network module inside the modules folder -> Option A

4. Quick Check:

   Root module calls submodules = true [OK]

Hint: Root module can call modules in subfolders [OK]

Common Mistakes:

• Thinking root module cannot use submodules
• Assuming root module must be empty
• Believing root module only has variables

4. You run terraform apply in your root module folder but get an error: "No configuration files found". What is the likely cause?

medium

A. You ran the command outside the root module folder

B. You forgot to run terraform init first

C. Your Terraform version is outdated

D. You have no internet connection

Solution

1. Step 1: Analyze the error message

   "No configuration files found" means Terraform cannot find .tf files in the current folder.

2. Step 2: Identify common cause

   This usually happens if you run terraform apply outside the root module folder where the files exist.

3. Final Answer:

   You ran the command outside the root module folder -> Option A

4. Quick Check:

   Run commands inside root module folder [OK]

Hint: Run commands inside root module folder with .tf files [OK]

Common Mistakes:

• Assuming init missing causes this error
• Blaming Terraform version or internet
• Not checking current folder location

5. You want to organize your Terraform project with a root module that calls two child modules: network and compute. Which folder structure and root module code is correct?

hard

A. root/
main.tf
network.tf
compute.tf

# main.tf does not call modules

B. root/
network/
main.tf
compute/
main.tf

# main.tf calls modules from root folder

C. root/
main.tf
modules/
network/
main.tf
compute/
main.tf

# main.tf calls both modules with module blocks

D. root/
main.tf
modules/
network/
main.tf
compute/
main.tf

# main.tf does not call any modules

Solution

1. Step 1: Understand proper module folder structure

   Child modules should be inside a modules folder under root for clarity and best practice.

2. Step 2: Confirm root module calls child modules

   The root module's main.tf must include module blocks to call network and compute modules.

3. Final Answer:

   Folder with modules subfolder and main.tf calling modules -> Option C

4. Quick Check:

   Root calls modules in modules/ folder [OK]

Hint: Put child modules in modules/ and call them in root main.tf [OK]

Common Mistakes:

• Placing modules outside modules/ folder
• Not calling modules in root main.tf
• Confusing separate folders as root module