Variable declaration syntax in Terraform - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Terraform variable declaration

Which of the following Terraform variable declarations correctly defines a string variable with a default value?

A variable region { type = string default = us-west-1 }

B variable "region" { type = string default = "us-west-1" }

C variable "region" { type = string default = us-west-1 }

D variable "region" { type = "string" default = "us-west-1" }

💡 Hint

Remember that string values must be quoted and the type keyword expects a type identifier without quotes.

In Terraform, variable names must be quoted strings. The type attribute expects a type identifier without quotes. The default value for a string must be quoted. Option B follows all these rules correctly.

❓ Configuration

intermediate

Correct syntax for list variable declaration

Which option correctly declares a Terraform variable named availability_zones as a list of strings with two default values?

A variable "availability_zones" { type = list(string) default = ["us-east-1a", "us-east-1b"] }

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

C variable "availability_zones" { type = list(string) default = us-east-1a, us-east-1b }

D variable availability_zones { type = list(string) default = ["us-east-1a", "us-east-1b"] }

💡 Hint

Check how the list type and default values are formatted.

Option A correctly uses list(string) as the type and provides a list of quoted strings as the default value. Variable names must be quoted strings. Option A misses the type parameter for list elements and lacks quotes around values. Option A misses quotes around the variable name. Option A has an invalid default value format.

❓ Architecture

advanced

Choosing variable types for infrastructure parameters

You want to declare a Terraform variable to accept a map of strings representing tags for AWS resources. Which declaration is correct?

A variable tags { type = map(string) default = { Environment = prod, Owner = team } }

B variable "tags" { type = map default = { "Environment" = "prod", "Owner" = "team" } }

C variable "tags" { type = map(string) default = { Environment = "prod", Owner = "team" } }

D variable "tags" { type = map(string) default = ["Environment" = "prod", "Owner" = "team"] }

💡 Hint

Remember the syntax for maps and quoting keys and values.

Option C correctly declares a variable named "tags" with type map(string) and a default map with quoted string values. Option C misses the type parameter for map elements. Option C misses quotes around the variable name and values. Option C uses square brackets which is invalid for maps.

❓ security

advanced

Declaring sensitive variables in Terraform

Which Terraform variable declaration correctly marks a variable as sensitive to avoid showing its value in logs?

A variable "db_password" { type = string sensitive = true }

B variable "db_password" { type = string sensitive = "true" }

C variable "db_password" { type = string sensitive = yes }

D variable "db_password" { type = string sensitive = 1 }

💡 Hint

Check the correct boolean syntax for the sensitive attribute.

Option A correctly sets sensitive = true as a boolean without quotes. Options B, C, and D use invalid boolean representations causing syntax errors.

❓ service_behavior

expert

Effect of variable default on module behavior

Given a Terraform module with a variable declared as:

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

What will be the value of instance_count if the module is called without specifying this variable?

A 0

B It will cause a runtime error due to missing variable

C null

D 3

💡 Hint

Check how Terraform handles variables with default values when not overridden.

When a variable has a default value, Terraform uses that value if no override is provided. So instance_count will be 3. It will not be 0 or null, and no error occurs.