Root module concept in Terraform - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the root module source.

Terraform

module "network" {
  source = "[1]"
}

Drag options to blanks, or click blank then click option'

Aroot_module

Baws_vpc

Cterraform

D./modules/network

Attempts:

3 left

💡 Hint

Common Mistakes

Using a provider name instead of a path.

Using 'root_module' as source which is not valid.

The root module uses a relative path to include local modules. Here, ./modules/network points to the network module folder.

2fill in blank

medium

Complete the code to declare a variable in the root module.

Terraform

variable "region" {
  type    = string
  default = "[1]"
}

Drag options to blanks, or click blank then click option'

Amodule

Bus-east-1

Cterraform

Droot

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'terraform' or 'module' as a region value.

Leaving the default empty.

The default value for the region variable is a valid AWS region string like us-east-1.

3fill in blank

hard

Fix the error in the root module output block.

Terraform

output "vpc_id" {
  value = module.network.[1]
}

Drag options to blanks, or click blank then click option'

Avpcid

BvpcId

Cvpc_id

DVpcId

Attempts:

3 left

💡 Hint

Common Mistakes

Using camelCase or PascalCase instead of snake_case.

Misspelling the attribute name.

Outputs must match the exact attribute name exposed by the module. Usually, Terraform uses snake_case like vpc_id.

4fill in blank

hard

Fill both blanks to correctly pass a variable from the root module to a child module.

Terraform

module "compute" {
  source = "./modules/compute"
  [1] = var.[2]
}

Drag options to blanks, or click blank then click option'

Aregion

Binstance_type

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing variable names between left and right sides.

Using the wrong variable names.

The root module passes its variable var.region to the child module's region input.

5fill in blank

hard

Fill all three blanks to define an output in the root module that references a child module's output.

Terraform

output "[1]" {
  value = module.compute.[2]
  description = "[3]"
}

Drag options to blanks, or click blank then click option'

Ainstance_id

CID of the compute instance

DCompute instance ID

Attempts:

3 left

💡 Hint

Common Mistakes

Mismatching output names and values.

Leaving description empty or unclear.

The output name and value must match the child module's output. The description explains the output clearly.

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