Object type definition in Terraform - Mini Project: Build & Apply

Terraform Object Type Definition

📖 Scenario: You are setting up a Terraform configuration to manage cloud resources. You want to define a clear structure for a server configuration using an object type. This helps you organize server details like name, CPU count, and memory size.

🎯 Goal: Create a Terraform variable with an object type that defines a server configuration with specific attributes.

📋 What You'll Learn

Define a variable named server_config with an object type

The object must have attributes: name (string), cpu (number), and memory (number)

Assign default values: name as "web-server", cpu as 4, and memory as 8192

💡 Why This Matters

🌍 Real World

Defining object types in Terraform helps organize complex configurations like server setups, making infrastructure code clearer and easier to maintain.

💼 Career

Cloud engineers and DevOps professionals use Terraform object types to create reusable and structured infrastructure modules.

1

Create the initial variable declaration

Create a Terraform variable named server_config with type object having attributes name (string), cpu (number), and memory (number). Do not add default values yet.

Terraform

variable "server_config" {
  type = object({
    name = string
    cpu = number
    memory = number
  })
  # Your code here
}

Need a hint?

Use variable "server_config" {} block and define type = object({...}) with the attributes inside.

2

Add default values to the object variable

Add a default attribute to the server_config variable with values: name as "web-server", cpu as 4, and memory as 8192.

Terraform

variable "server_config" {
  type = object({
    name = string
    cpu = number
    memory = number
  })
  # Add default values here
}

Need a hint?

Use default = { name = "web-server", cpu = 4, memory = 8192 } inside the variable block.

3

Reference the object variable in a resource

Create a Terraform resource aws_instance named example that uses the server_config variable's attributes for instance_type and tags.Name. Use cpu to decide instance type as "t3.medium" if cpu is 2, otherwise "t3.large". Use server_config.name for the tag.

Terraform

resource "aws_instance" "example" {
  # Use server_config variable attributes here
}

Need a hint?

Use a conditional expression for instance_type and reference var.server_config.name for tags.

4

Add memory attribute usage in user_data

Add a user_data attribute to the aws_instance.example resource that echoes the memory size from server_config.memory in megabytes using a shell command.

Terraform

resource "aws_instance" "example" {
  instance_type = var.server_config.cpu == 2 ? "t3.medium" : "t3.large"
  ami           = "ami-0c55b159cbfafe1f0"

  tags = {
    Name = var.server_config.name
  }

  # Add user_data here
}

Need a hint?

Use a heredoc for user_data and include the memory value with interpolation.