Default values in Terraform - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Configuration

intermediate

What is the default value of the variable 'instance_type'?

Given this Terraform variable declaration, what is the default value of instance_type?

variable "instance_type" {
  type    = string
  default = "t2.micro"
}

A ""

B "t2.micro"

C null

D "t3.medium"

💡 Hint

Look at the default attribute inside the variable block.

The default attribute sets the default value for the variable if no value is provided during deployment. Here, it is set to "t2.micro".

❓ service_behavior

intermediate

What happens if a variable with no default is not provided?

Consider this Terraform variable declaration without a default value:

variable "region" {
  type = string
}

What happens if you run terraform apply without providing a value for region?

A Terraform prompts the user to input a value for 'region'.

B Terraform throws a syntax error and stops.

C Terraform automatically assigns the provider's default region.

D Terraform uses an empty string as the default value.

💡 Hint

Think about how Terraform handles required variables without defaults.

If a variable has no default value and no value is provided, Terraform will prompt the user to enter a value during execution.

❓ Architecture

advanced

How does default value affect module reuse?

You have a Terraform module with a variable environment that has a default value "dev". You want to reuse this module for production without changing the module code.

Which approach correctly overrides the default value when calling the module?

Terraform

<pre>module "app" {
  source = "./app_module"
  # How to override environment?
}</pre>

A Rename the variable in the module to "prod".

B Change the default value inside the module variable to "prod".

C Set an environment variable named TF_VAR_environment to "prod" before running Terraform.

D Add <code>environment = "prod"</code> inside the module block.

💡 Hint

Think about how to pass values to modules to override defaults.

To override a module variable's default, you pass the new value in the module block. Changing the module code or renaming variables is not needed.

❓ security

advanced

What risk arises from default sensitive variable values?

A Terraform variable is declared as sensitive with a default value containing a password:

variable "db_password" {
  type      = string
  sensitive = true
  default   = "defaultPass123"
}

What is the main security risk of this setup?

A The password will be encrypted automatically, so no risk exists.

B Terraform will ignore the sensitive flag and print the password always.

C The default password may be exposed if the code is shared publicly.

D Terraform will fail to apply because sensitive variables cannot have defaults.

💡 Hint

Consider what happens if code with default secrets is stored in public repositories.

Storing default sensitive values like passwords in code risks exposure if the code is shared or leaked, even if marked sensitive.

🧠 Conceptual

expert

What is the output of this Terraform expression with default values?

Given the following Terraform locals and variables:

variable "count" {
  type    = number
  default = 3
}

locals {
  total = var.count + 2
}

What is the value of local.total if no value is provided for count?

A 5

B 3

C 2

D null

💡 Hint

Remember how default values are used when no input is given.

The variable count defaults to 3. The local total adds 2 to this, resulting in 5.