Output values after apply in Terraform - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

Output value of a computed resource attribute

Given the Terraform configuration below, what will be the output value of instance_ip after applying?

Terraform

resource "aws_instance" "example" {
  ami           = "ami-12345678"
  instance_type = "t2.micro"

  tags = {
    Name = "example-instance"
  }
}

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

A "The public IP address of the instance, e.g., 54.123.45.67"

B "The AMI ID used, e.g., ami-12345678"

C "The instance type, e.g., t2.micro"

D "An empty string because public_ip is not set"

💡 Hint

The output references the public_ip attribute of the aws_instance resource.

The output value references aws_instance.example.public_ip, which is the public IP address assigned to the instance after creation.

❓ Configuration

intermediate

Output value from a map variable

What will be the output of region_name after applying this Terraform configuration?

Terraform

variable "regions" {
  type = map(string)
  default = {
    us_east_1 = "US East (N. Virginia)"
    eu_west_1 = "EU (Ireland)"
  }
}

output "region_name" {
  value = var.regions["eu_west_1"]
}

A "eu_west_1"

B "EU (Ireland)"

C "US East (N. Virginia)"

D "null"

💡 Hint

The output accesses the map variable with key "eu_west_1".

The output value is the string mapped to the key "eu_west_1" in the variable regions, which is "EU (Ireland)".

❓ Architecture

advanced

Output value of a list of resource IDs

After applying the following Terraform code, what will be the output value of subnet_ids?

Terraform

resource "aws_subnet" "example" {
  count = 3
  vpc_id     = "vpc-123456"
  cidr_block = "10.0.${count.index}.0/24"
}

output "subnet_ids" {
  value = aws_subnet.example[*].id
}

A ["subnet-abc123", "subnet-def456", "subnet-ghi789"]

B ["10.0.0.0/24", "10.0.1.0/24", "10.0.2.0/24"]

C "subnet-abc123"

D null

💡 Hint

The output uses the splat operator to collect all subnet IDs.

The output collects the id attribute from all three aws_subnet resources into a list of subnet IDs.

❓ security

advanced

Outputting sensitive values

Consider this Terraform output configuration. What will happen after apply?

Terraform

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

output "database_password" {
  value     = var.db_password
  sensitive = true
}

A The password will be shown in the output after apply.

B The password will be printed in plain text in the Terraform state file only.

C The password will be hidden in the output and not shown in the CLI.

D Terraform will raise an error because sensitive outputs are not allowed.

💡 Hint

Sensitive outputs are designed to hide values in CLI output.

Marking an output as sensitive hides its value from CLI output but still stores it encrypted in the state file.

✅ Best Practice

expert

Output value referencing a resource attribute that may not exist

What will be the output value of bucket_arn after applying this Terraform configuration if the resource aws_s3_bucket.example is conditionally created with count = 0?

Terraform

resource "aws_s3_bucket" "example" {
  count = 0
  bucket = "my-example-bucket"
}

output "bucket_arn" {
  value = aws_s3_bucket.example[0].arn
}

A "" (empty string)

B null

C The ARN string of the bucket, e.g., arn:aws:s3:::my-example-bucket

D A runtime error because the resource does not exist

💡 Hint

Accessing an index of a resource with count=0 causes an error.

Since the resource count is zero, the list aws_s3_bucket.example is empty. Accessing index 0 causes a runtime error.