Creating Your First AWS EC2 Instance

Estimated time: 30 minutes

Overview

Questions

• How do I define a cloud resource in Terraform?
• What is an aws_instance block?
• How does Terraform preview and apply changes?
• How can I safely destroy cloud resources?

Objectives

• Add an EC2 instance resource to main.tf.
• Understand key arguments of the aws_instance block.
• Use terraform plan to preview changes.
• Use terraform apply to create infrastructure.
• Destroy resources safely with terraform destroy.

Adding an EC2 Instance to main.tf

---

We extend our configuration from Episode 2 by adding the aws_instance resource.

Add this block to your main.tf:

resource "aws_instance" "example" {
  ami           = "ami-0adebe3adcec1fa34"   # Rocky Linux 9 AMI
  instance_type = "t3.micro"

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

Understanding the Key Arguments

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• resource "aws_instance" "example"
  Creates an EC2 instance and names it example in the Terraform state.

• ami
  Identifies the Amazon Machine Image. Different AMIs represent different OSes.

• instance_type
  Sets CPU & memory size.

• tags
  Adds human-readable metadata in AWS.

Previewing the Change

---

Run:

BASH

terraform plan

Terraform will show:

• one resource to add
  
• full details of what will be created
  
• no changes to existing resources

This preview step is important—nothing changes until we apply.

Creating the EC2 Instance

---

Apply the plan:

BASH

terraform apply

You will be prompted:

Do you want to perform these actions? Only ‘yes’ will be accepted.

Type:

yes

Within about 20–60 seconds the EC2 instance will launch.

Terraform will output:

• the instance ID
  
• the public DNS
  
• the public IP

These values are now part of Terraform’s state, so it knows the instance exists.

Verifying the Instance in AWS

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Visit your AWS Console:

• EC2 → Instances
  
• Confirm the instance named terraform-example is running

Destroying the Instance (Optional)

---

Terraform can remove everything it created:

BASH

terraform destroy

This is useful while practicing to avoid unnecessary AWS charges.

Challenge

Practice: Change the Instance Type

Modify this line:

instance_type = "t3.micro"

Change it to:

instance_type = "t3.small"

Run:

BASH

terraform plan

What does Terraform tell you it will do?

Show me the solution

Terraform should report an in-place update, changing only the instance type:

instance_type: “t3.micro” -> “t3.small”

No resources are destroyed unless the change requires replacement.

Key Points

• Terraform uses resource blocks to define cloud infrastructure.
• The AWS provider includes many resource types; EC2 is one of them.
• terraform plan previews changes before they occur.
• terraform apply creates or updates cloud resources.
• Terraform maintains state so it always knows what exists.
• terraform destroy safely removes all managed resources.