Module inputs (variables) in Terraform - Mini Project: Build & Apply

Terraform Module Inputs with Variables

📖 Scenario: You are creating a reusable Terraform module to deploy a simple AWS EC2 instance. To make the module flexible, you will use variables as inputs.

🎯 Goal: Build a Terraform module that accepts input variables for instance_type and ami_id, and uses them to configure an AWS EC2 instance resource.

📋 What You'll Learn

Create variables for instance_type and ami_id with default values

Use the variables in the aws_instance resource configuration

Output the instance ID after deployment

💡 Why This Matters

🌍 Real World

Terraform modules often use variables to make infrastructure reusable and configurable for different environments or projects.

💼 Career

Understanding how to use module inputs is essential for cloud engineers and DevOps professionals to write flexible and maintainable infrastructure as code.

1

Create variables for instance type and AMI ID

Create two variables in Terraform: instance_type with default value t2.micro, and ami_id with default value ami-12345678. Use the variable block syntax.

Terraform

# Define variables for instance_type and ami_id
# Your code here

Need a hint?

Use variable "name" {} blocks with default values.

2

Add provider configuration

Add the AWS provider configuration block with region set to us-east-1. Use the provider "aws" block.

Terraform

variable "instance_type" {
  type    = string
  default = "t2.micro"
}

variable "ami_id" {
  type    = string
  default = "ami-12345678"
}

# Add AWS provider configuration here
# Your code here

Need a hint?

Use provider "aws" { region = "us-east-1" } to set the AWS region.

3

Create the AWS EC2 instance resource using variables

Create an aws_instance resource named example that uses the variables instance_type and ami_id for its instance_type and ami attributes respectively.

Terraform

variable "instance_type" {
  type    = string
  default = "t2.micro"
}

variable "ami_id" {
  type    = string
  default = "ami-12345678"
}

provider "aws" {
  region = "us-east-1"
}

# Create aws_instance resource using variables
# Your code here

Need a hint?

Use var.instance_type and var.ami_id to reference variables inside the resource.

4

Add output for the instance ID

Add an output named instance_id that outputs the id attribute of the aws_instance.example resource.

Terraform

variable "instance_type" {
  type    = string
  default = "t2.micro"
}

variable "ami_id" {
  type    = string
  default = "ami-12345678"
}

provider "aws" {
  region = "us-east-1"
}

resource "aws_instance" "example" {
  instance_type = var.instance_type
  ami           = var.ami_id
}

# Add output for instance ID
# Your code here

Need a hint?

Use output "name" { value = resource.attribute } syntax.