Resource block syntax in Terraform - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Configuration

intermediate

Identify the correct resource block syntax for creating an AWS S3 bucket

Which resource block correctly defines an AWS S3 bucket named "my_bucket" with versioning enabled?

A

resource "aws_s3_bucket" "my_bucket" {
  bucket = "my_bucket"
  versioning = true
}

B

resource aws_s3_bucket my_bucket {
  bucket = "my_bucket"
  versioning = true
}

C

resource "aws_s3_bucket" "my_bucket" {
  name = "my_bucket"
  versioning = {
    enabled = true
  }
}

D

resource "aws_s3_bucket" "my_bucket" {
  bucket = "my_bucket"
  versioning {
    enabled = true
  }
}

💡 Hint

Remember that nested blocks like versioning require a block syntax, not just an attribute assignment.

Option D correctly uses the resource block syntax with the nested versioning block and the enabled attribute set to true. Option D misses quotes and uses incorrect versioning syntax. Option D uses name instead of bucket attribute. Option D incorrectly assigns versioning as a boolean instead of a block.

❓ service_behavior

intermediate

Effect of missing required attribute in resource block

What happens if you define an AWS EC2 instance resource block without specifying the required attribute "ami"?

Terraform

resource "aws_instance" "example" {
  instance_type = "t2.micro"
}

A Terraform will ignore the missing attribute and create the instance with instance_type only.

B Terraform will create the instance with a default AMI automatically.

C Terraform plan will fail with an error about missing required attribute "ami".

D Terraform will create the instance but it will be stopped by default.

💡 Hint

Think about how Terraform validates resource blocks before applying.

The ami attribute is required for aws_instance. Terraform validates resource blocks and will fail the plan phase if required attributes are missing. It does not provide defaults or partial creations.

❓ Architecture

advanced

Correct resource block to create a VPC with CIDR block and enable DNS support

Which resource block correctly creates an AWS VPC with CIDR block "10.0.0.0/16" and enables DNS support?

A

resource "aws_vpc" "main" {
  cidr = "10.0.0.0/16"
  enable_dns = true
}

B

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  enable_dns_support = true
}

C

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  dns_support = true
}

D

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  enable_dns_hostnames = true
}

💡 Hint

Check the exact attribute names required by the AWS VPC resource.

Option B uses the correct attribute names cidr_block and enable_dns_support. Option B uses incorrect attribute names. Option B uses dns_support which is invalid. Option B enables DNS hostnames but not DNS support.

❓ security

advanced

Resource block to create a security group allowing inbound HTTP traffic

Which resource block correctly creates an AWS security group allowing inbound HTTP (port 80) traffic from anywhere?

A

resource "aws_security_group" "web_sg" {
  name = "web_sg"
  ingress {
    from_port = 80
    to_port = 80
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }
}

B

resource "aws_security_group" "web_sg" {
  name = "web_sg"
  ingress = [{
    from_port = 80
    to_port = 80
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }]
}

C

resource "aws_security_group" "web_sg" {
  name = "web_sg"
  ingress {
    port = 80
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }
}

D

resource "aws_security_group" "web_sg" {
  name = "web_sg"
  ingress {
    from_port = 80
    to_port = 80
    protocol = "tcp"
    cidr_block = "0.0.0.0/0"
  }
}

💡 Hint

Remember the correct attribute names and types for ingress rules.

Option A correctly uses the ingress block with from_port, to_port, protocol, and cidr_blocks as a list. Option A incorrectly assigns ingress as a list directly. Option A uses port which is invalid. Option A uses cidr_block instead of cidr_blocks list.

✅ Best Practice

expert

Correct way to reference another resource's attribute in a resource block

Given a resource "aws_vpc" "main" with attribute "id", which resource block correctly references this VPC ID when creating a subnet?

Terraform

resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
}

resource "aws_subnet" "subnet1" {
  vpc_id = ???
  cidr_block = "10.0.1.0/24"
}

A vpc_id = aws_vpc.main.id

B vpc_id = "aws_vpc.main.id"

C vpc_id = ${aws_vpc.main.id}

D vpc_id = $aws_vpc.main.id

💡 Hint

Terraform 0.12+ allows direct references without interpolation syntax.

Option A uses the correct direct reference syntax. Option A treats the reference as a string literal. Option A uses deprecated interpolation syntax which is invalid without quotes. Option A uses invalid shell-style variable syntax.