Variables and Outputs

Variables and Outputs Quiz

Quiz

Question 1 of 27 (0 answered)

Question 1

What is the PRIMARY benefit of using variables in Terraform instead of hardcoded values?

Variables make the code run faster Variables enable reusing the same configuration across multiple environments Variables are required by Terraform to run properly Variables automatically validate input values

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The primary benefit is reusability - you can use the same Terraform code across dev, staging, and production by simply changing variable values, without modifying the code itself.

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The primary benefit is reusability - you can use the same Terraform code across dev, staging, and production by simply changing variable values, without modifying the code itself.

Think about deploying the same infrastructure to different environments.

Question 2

Which of the following are primitive types in Terraform?

string list number bool map

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Primitive types in Terraform are: string, number, and bool. List and map are collection types (complex types).

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Primitive types in Terraform are: string, number, and bool. List and map are collection types (complex types).

Primitive types are the simplest, most basic data types.

Question 3

A variable without a default value is optional and can be omitted when running Terraform.

True False

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Variables without default values are REQUIRED and must be provided either through .tfvars files, command-line flags, or environment variables. Only variables WITH default values are optional.

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Variables without default values are REQUIRED and must be provided either through .tfvars files, command-line flags, or environment variables. Only variables WITH default values are optional.

Consider what happens when Terraform doesn’t know what value to use.

Question 4

To reference a variable named ‘region’ in your Terraform configuration, you would use: _____

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Variables are referenced using the var. prefix followed by the variable name: var.region.

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Variables are referenced using the var. prefix followed by the variable name: var.region.

All variable references start with a three-letter prefix.

Question 5

What will be the final value of instance_type given this precedence chain?

# variables.tf: default = "t2.micro"
# TF_VAR_instance_type = "t2.small"
# terraform.tfvars: instance_type = "t2.medium"
# Command: terraform apply -var="instance_type=t2.large"

What will this code output?

t2.micro t2.small t2.medium t2.large

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Command-line -var flags have the highest precedence and override all other sources. The precedence order is: default < environment vars < .tfvars < -var flags.

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Command-line -var flags have the highest precedence and override all other sources. The precedence order is: default < environment vars < .tfvars < -var flags.

Command-line flags win over all other variable sources.

Question 6

What is the difference between a Map and an Object in Terraform?

Map: Flexible key-value pairs where all values must be the same type. Keys can be any string, and you can add/remove keys dynamically.

Object: Fixed structure with predefined keys where each field can have a different type. Schema enforces required fields.

Example:

Map: map(string) - any keys, all string values
Object: object({name=string, age=number}) - fixed keys, mixed types

Did you get it right?

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Question 7

Arrange these variable value sources from LOWEST to HIGHEST precedence:

Drag to arrange in the correct order (lowest precedence first)

⋮⋮ Default value in variable block

⋮⋮ Environment variables (TF_VAR_*)

⋮⋮ terraform.tfvars file

⋮⋮ -var command-line flag

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Correct precedence order: 1) Default values (lowest), 2) Environment variables, 3) .tfvars files, 4) -var command-line flags (highest).

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Correct precedence order: 1) Default values (lowest), 2) Environment variables, 3) .tfvars files, 4) -var command-line flags (highest).

Question 8

Complete the variable declaration to accept a list of strings:

Fill in the missing type constraint

variable "availability_zones" {
  type = _____
  default = ["us-east-1a", "us-east-1b"]
}

Your answer:

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For a list containing strings, the type constraint is list(string). This ensures the variable only accepts a list where all elements are strings.

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For a list containing strings, the type constraint is list(string). This ensures the variable only accepts a list where all elements are strings.

Question 9

When using for_each with a set variable to create multiple S3 buckets, what advantage does this provide over using count with a list?

Sets are faster to process than lists Sets automatically prevent duplicate values Removing a bucket from the set won’t affect other buckets (unlike count which uses indexes) Sets can contain different data types

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The key advantage is stability: with for_each on sets, resources are keyed by value (e.g., aws_s3_bucket.buckets["app-logs"]). Removing one doesn’t shift indexes like with count, preventing unintended resource destruction/recreation.

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Think about what happens when you remove the middle element from a list vs a set.

Question 10

Which validation functions can be used in variable validation blocks?

contains() - check if value exists in list can() - test if expression succeeds regex() - match string patterns length() - check string/list length All of the above

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All of these functions (and more) can be used in validation blocks. Common patterns include: contains() for allowed values, can(regex()) for pattern matching, length() for size constraints, and can() to safely test expressions.

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Validation blocks support a wide range of Terraform functions.

Question 11

Setting sensitive = true on a variable encrypts the value in the state file.

True False

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FALSE. The sensitive flag only hides the value in console output and logs. It does NOT encrypt the value - sensitive values are still stored in plain text in the state file. Use external secret management (AWS Secrets Manager, Vault) for true security.

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Think about where Terraform actually stores resource data.

Question 12

To mark a variable as sensitive and hide its value in Terraform output, set _____ = true

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The sensitive attribute when set to true prevents Terraform from showing the variable value in plan and apply output, displaying <sensitive> instead.

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The sensitive attribute when set to true prevents Terraform from showing the variable value in plan and apply output, displaying <sensitive> instead.

The attribute name describes what kind of data it protects.

Question 13

Given this configuration, how many subnets will be created?

variable "availability_zones" {
  default = ["us-east-1a", "us-east-1b", "us-east-1c"]
}

resource "aws_subnet" "public" {
  count = length(var.availability_zones)
  availability_zone = var.availability_zones[count.index]
  cidr_block = "10.0.${count.index}.0/24"
}

What will this code output?

1 subnet 2 subnets 3 subnets 4 subnets

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3 subnets will be created. length(var.availability_zones) returns 3 (number of items in the list), so count = 3. Each iteration creates one subnet in a different AZ: us-east-1a, us-east-1b, us-east-1c.

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Count the number of items in the availability_zones list.

Question 14

What is the correct way to access a module’s output value in the root module?

output.module_name.output_name module.output_name.module_name module.module_name.output_name var.module_name.output_name

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Module outputs are accessed using module.<module_name>.<output_name>. For example, if you have module "vpc" with output "vpc_id", you reference it as module.vpc.vpc_id.

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Module outputs are accessed using module.<module_name>.<output_name>. For example, if you have module "vpc" with output "vpc_id", you reference it as module.vpc.vpc_id.

The syntax starts with the keyword ‘module’.

Question 15

What is the purpose of output values in Terraform?

Output values serve four main purposes:

Display information after terraform apply (e.g., IP addresses, URLs)
Share data between root and child modules
Query infrastructure state using terraform output
Provide values to external systems (via -json flag)

Example:

output "instance_ip" {
  value = aws_instance.web.public_ip
}

Query with: terraform output instance_ip

Did you get it right?

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Question 16

Complete the validation block to ensure the environment is one of: dev, staging, or prod

Fill in the missing condition

variable "environment" {
  type = string
  
  validation {
    condition     = _____
    error_message = "Environment must be dev, staging, or prod."
  }
}

Your answer:

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The contains() function checks if a value exists in a list. Syntax: contains(list, value). This validates that var.environment is one of the allowed values.

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The contains() function checks if a value exists in a list. Syntax: contains(list, value). This validates that var.environment is one of the allowed values.

Question 17

Which statements about complex types are TRUE?

A map(object({…})) combines flexible keys with structured values A list(object({…})) maintains order and enforces a consistent schema An object can have fields of different types (string, number, bool) A map requires all values to be the same type All of the above

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All statements are true. Complex types combine basic types: map of objects gives flexibility + structure, list of objects gives order + schema, objects allow mixed types per field, and maps enforce same type for all values.

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Complex types build on the rules of their component types.

Question 18

When using *.auto.tfvars files, Terraform loads them automatically in alphabetical order without needing the -var-file flag.

True False

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TRUE. Files matching *.auto.tfvars or *.auto.tfvars.json are automatically loaded by Terraform in alphabetical order, without requiring explicit -var-file flags.

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TRUE. Files matching *.auto.tfvars or *.auto.tfvars.json are automatically loaded by Terraform in alphabetical order, without requiring explicit -var-file flags.

The ‘.auto.’ in the filename is a hint about its behavior.

Question 19

Which approach is BEST PRACTICE for storing database passwords in Terraform?

Set sensitive = true in the variable block and store in terraform.tfvars Store in environment variables with TF_VAR_ prefix Fetch from external secret management system (AWS Secrets Manager, Vault) at runtime Encrypt the terraform.tfvars file with GPG

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Best practice is to fetch secrets from external secret management at runtime using data sources. This keeps secrets out of your code, state files, and git. The sensitive flag only hides display output but doesn’t encrypt storage.

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Think about where secrets should actually be stored and managed.

Question 20

What will happen when you run terraform apply with this configuration?

variable "project_name" {
  type = string
  # No default value
}

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = var.project_name
  }
}

What will this code output?

Terraform will use an empty string for project_name Terraform will prompt for the project_name value Terraform will skip creating the VPC Terraform will generate a random project_name

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Terraform will prompt you to enter a value for project_name because it’s a required variable (no default). You can provide it interactively, via -var flag, environment variable, or .tfvars file.

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Terraform will prompt you to enter a value for project_name because it’s a required variable (no default). You can provide it interactively, via -var flag, environment variable, or .tfvars file.

Required variables must be provided somehow.

Question 21

To set a Terraform variable via environment variable, use the prefix _____

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Environment variables for Terraform must use the TF_VAR_ prefix. For example, to set variable region, use: export TF_VAR_region="us-east-1"

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Environment variables for Terraform must use the TF_VAR_ prefix. For example, to set variable region, use: export TF_VAR_region="us-east-1"

The prefix is three characters followed by an underscore.

Question 22

Explain the difference between count and for_each when creating multiple resources.

count:

Creates resources indexed by number: [0], [1], [2]
Order matters; removing middle item shifts indexes
Can cause unintended resource destruction/recreation
Use for: simple, fixed-count resources

for_each:

Creates resources keyed by value: ["web"], ["app"]
No index shifting; remove by name
Safer for dynamic resource sets
Works with: sets and maps
Use for: resources that change dynamically

Example impact: With count, removing [1] makes [2] become [1] → destroys & recreates. With for_each, removing ["app"] only removes that one resource.

Did you get it right?

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Question 23

In a map of objects variable, what does each.key represent when used with for_each?

The index number of the current iteration The map key (e.g., ‘web’, ‘app’, ‘db’) The entire object value The first field of the object

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each.key represents the map key in a for_each loop. For instances = {web = {...}, app = {...}}, each.key would be “web” or “app”. Use each.value to access the object fields.

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each.key represents the map key in a for_each loop. For instances = {web = {...}, app = {...}}, each.key would be “web” or “app”. Use each.value to access the object fields.

Think about the structure: map has keys and values.

Question 24

Complete the object type definition for an instance configuration:

Fill in the missing type structure

variable "instance_config" {
  type = _____
  
  default = {
    instance_type = "t2.micro"
    ami = "ami-12345"
    monitoring = true
  }
}

Your answer:

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An object type requires defining the schema with field names and their types: object({instance_type = string, ami = string, monitoring = bool}). Field order doesn’t matter, but all fields must be defined.

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Question 25

Which are valid ways to provide variable values to Terraform? (Select all that apply)

terraform.tfvars file (automatically loaded) Command-line: -var=“key=value” Environment variable: TF_VAR_key=value Custom file: terraform apply -var-file=“custom.tfvars” All of the above

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All of these are valid methods to provide variable values. Terraform supports multiple input methods with different precedence levels, giving flexibility in how you configure your infrastructure.

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All of these are valid methods to provide variable values. Terraform supports multiple input methods with different precedence levels, giving flexibility in how you configure your infrastructure.

Terraform provides multiple ways to set variables for flexibility.

Question 26

The ‘any’ type should be preferred over specific types like ‘string’ or ’number’ because it provides more flexibility.

True False

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FALSE. While ‘any’ is more flexible, specific types are preferred because they provide type safety, better validation, and clearer documentation. Only use ‘any’ when the type truly varies based on input or when building generic modules.

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Consider the trade-off between flexibility and safety/clarity.

Question 27

Arrange these file organization elements in the recommended structure:

Drag to arrange in logical order for a Terraform project

⋮⋮ variables.tf (declarations)

⋮⋮ terraform.tfvars (common values)

⋮⋮ main.tf (resources)

⋮⋮ outputs.tf (output definitions)

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Recommended organization: 1) variables.tf for declarations, 2) terraform.tfvars for values, 3) main.tf for resources, 4) outputs.tf for outputs. This separation makes code easier to navigate and maintain.

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Last updated on January 6, 2026

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