Why dynamic blocks reduce repetition in Terraform - See It in Action

Why dynamic blocks reduce repetition

📖 Scenario: You are managing cloud infrastructure using Terraform. You need to create multiple similar nested blocks inside a resource configuration. Writing each block manually causes repetition and makes the code harder to maintain.

🎯 Goal: Learn how to use dynamic blocks in Terraform to reduce repetition by generating multiple nested blocks from a list variable.

📋 What You'll Learn

Create a list variable with exact values

Create a resource with repeated nested blocks

Use a dynamic block to generate nested blocks from the list

Complete the resource configuration with dynamic blocks

💡 Why This Matters

🌍 Real World

Cloud engineers often need to create multiple similar nested blocks in Terraform configurations. Dynamic blocks help reduce manual repetition and errors.

💼 Career

Understanding dynamic blocks is essential for writing clean, maintainable Terraform code in real-world cloud infrastructure projects.

1

Create a list variable with subnet names

Create a Terraform variable called subnet_names with the exact list ["subnet-a", "subnet-b", "subnet-c"].

Terraform

# Your code here

Need a hint?

Use variable block with type = list(string) and default set to the exact list.

2

Create a resource with repeated nested blocks manually

Create a Terraform resource aws_vpc named main with three nested subnet blocks. Each subnet block should have a name attribute set to "subnet-a", "subnet-b", and "subnet-c" respectively.

Terraform

variable "subnet_names" {
  type    = list(string)
  default = ["subnet-a", "subnet-b", "subnet-c"]
}

# Your code here

Need a hint?

Write three subnet blocks inside the aws_vpc resource with the exact name values.

3

Use a dynamic block to generate subnets

Replace the three manual subnet blocks inside aws_vpc.main with a single dynamic block named subnet that iterates over var.subnet_names and sets name = subnet.value inside the block.

Terraform

variable "subnet_names" {
  type    = list(string)
  default = ["subnet-a", "subnet-b", "subnet-c"]
}

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

  # Your code here
}

Need a hint?

Use dynamic "subnet" with for_each = var.subnet_names and set name = subnet.value inside content.

4

Complete the resource configuration with dynamic blocks

Ensure the aws_vpc.main resource has the cidr_block set to "10.0.0.0/16" and uses the dynamic "subnet" block iterating over var.subnet_names with name = subnet.value inside content.

Terraform

variable "subnet_names" {
  type    = list(string)
  default = ["subnet-a", "subnet-b", "subnet-c"]
}

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

  # Your code here
}

Need a hint?

Verify the resource has cidr_block and the dynamic "subnet" block with correct iteration and content.