Count for multiple instances in Terraform - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Configuration

intermediate

Count Usage for Multiple Instances

Given the Terraform resource below, how many instances will be created?

Terraform

resource "aws_instance" "example" {
  count         = 3
  ami           = "ami-123456"
  instance_type = "t2.micro"
}

A 0

B 1

C 3

D Depends on the AWS account limits

💡 Hint

The count argument defines how many copies of the resource are created.

The count argument set to 3 means Terraform will create 3 instances of the aws_instance resource.

❓ Architecture

intermediate

Dynamic Count with Variable

If the variable "instance_count" is set to 5, how many instances will this Terraform code create?

Terraform

variable "instance_count" {
  type    = number
  default = 5
}

resource "aws_instance" "example" {
  count         = var.instance_count
  ami           = "ami-123456"
  instance_type = "t2.micro"
}

A 5

B 1

C 0

D Depends on the AWS region

💡 Hint

The count uses the variable value directly.

The count is set to the variable instance_count which is 5, so 5 instances will be created.

❓ service_behavior

advanced

Count with Conditional Expression

What is the number of instances created by this Terraform resource if var.create_instances is false?

Terraform

variable "create_instances" {
  type    = bool
  default = false
}

resource "aws_instance" "example" {
  count         = var.create_instances ? 4 : 0
  ami           = "ami-123456"
  instance_type = "t2.micro"
}

A 4

B Terraform will throw an error

C 1

D 0

💡 Hint

The count uses a conditional expression based on the boolean variable.

Since var.create_instances is false, the count evaluates to 0, so no instances are created.

❓ security

advanced

Count with Sensitive Variable

If the variable "instance_count" is marked sensitive and set to 2, how many instances will Terraform create?

Terraform

variable "instance_count" {
  type      = number
  sensitive = true
  default   = 2
}

resource "aws_instance" "example" {
  count         = var.instance_count
  ami           = "ami-123456"
  instance_type = "t2.micro"
}

A 2

B 1

C Terraform will not create any instances because the variable is sensitive

D Terraform will throw a sensitive variable error

💡 Hint

Sensitive variables hide values in logs but do not affect resource creation.

Sensitive variables only hide their values in output and logs; they do not affect the count behavior. Terraform creates 2 instances.

✅ Best Practice

expert

Count with Complex Expression

What is the count value and number of instances created by this resource if var.env is "prod"?

Terraform

variable "env" {
  type    = string
  default = "prod"
}

resource "aws_instance" "example" {
  count = var.env == "prod" ? 5 : 2
  ami           = "ami-123456"
  instance_type = "t2.micro"
}

A count = 2, creates 2 instances

B count = 5, creates 5 instances

C count = 0, creates 0 instances

D Terraform throws an error due to invalid count expression

💡 Hint

The count uses a conditional expression comparing the environment variable.

Since var.env is "prod", the count expression evaluates to 5, so Terraform creates 5 instances.