🚀 Creating an EC2 Instance from Scratch with Terraform

 By Raees Qazi | DevOps Engineer | Learner | Mentor | Creator

Today, we’re going to create an EC2 instance from scratch using Terraform. We’ll go step-by-step and learn how to:

✅ Generate an SSH key
 ✅ Create a key pair, VPC, and security group
 ✅ Launch an EC2 instance
 ✅ Use interpolation to extract values
 ✅ Control instance state (stop/start) with Terraform

Let’s get started — in the simplest and most practical way possible.

✅ Prerequisites

Before jumping into code, make sure:

• You have already created the Terraform provider file
• Terraform is initialized (terraform init)
• AWS CLI is configured with an IAM user

All set? Great! Let’s begin.

🔑 Step 1: Generate SSH Key Pair

ssh-keygen
# Name it: terra-key-auto

This will generate two files:

• terra-key-auto (private key)
• terra-key-auto.pub (public key)

We’ll use these to access our EC2 machine.

✍️ Step 2: Write ec2.tf File

Let’s write all our resources step by step in one file:

# ec2.tf
# 1. Create SSH Key Pair in AWS
resource "aws_key_pair" "my_ssh_key" {
  key_name   = "terra-key-auto"
  public_key = file("/home/ubuntu/terra-key-auto.pub") # Path to your public key
}
# 2. Use Default VPC
resource "aws_default_vpc" "default" {}
# 3. Create Security Group
resource "aws_security_group" "my_sg" {
  name        = "TWS-SG"
  description = "this is a sooper se ooper upper security group"
  vpc_id      = aws_default_vpc.default.id
  ingress {
    from_port   = 22
    to_port     = 22
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
    description = "this is for ssh access"
  }
  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
    description = "this is for http access"
  }
  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
    description = "this is for outside world requests from instance"
  }
}
# 4. Launch EC2 Instance
resource "aws_instance" "my_instance" {
  ami             = "ami-xxxxxxxxxxxxxxxxx"      # Replace with valid AMI ID
  instance_type   = "t2.micro"
  key_name        = aws_key_pair.my_ssh_key.key_name
  security_groups = [aws_security_group.my_sg.name]
  tags = {
    Name = "My-Auto-server"
  }
}
# 5. Control EC2 Instance State (Stop by default)
resource "aws_ec2_instance_state" "my_state" {
  instance_id = aws_instance.my_instance.id
  state       = "stopped"
}

📘 Explanation

• aws_key_pair uploads your public SSH key to AWS so you can log into EC2 securely.
• aws_default_vpc lets you use the default networking setup.
• aws_security_group allows:
• SSH access on port 22
• HTTP access on port 80
• All outbound traffic for internet access
• aws_instance launches your virtual machine.
• aws_ec2_instance_state controls the instance’s state (stopped or running).
• Interpolation is used like this:
• key_name = aws_key_pair.my_ssh_key.key_name
• This pulls a value from one resource to use in another — that’s interpolation!

🚀 Deploy Infrastructure

Once your code is ready, run:

terraform plan
terraform apply

And… ✨ Jaddo is in front of you!
 Your EC2 instance is created, and the public IP is ready to be used.

🔁 Change Instance State (From Stopped to Running)

Want to start the instance?

Simply go to this block:

resource "aws_ec2_instance_state" "my_state" {
  instance_id = aws_instance.my_instance.id
  state       = "stopped"  # change this to "running"
}

Change stopped to running and run:

terraform apply

💥 Now your instance is running.

🙌 Wrap Up

In this blog, we learned how to:

✅ Generate and use SSH keys
 ✅ Create VPC and security groups
 ✅ Launch and control EC2 instances using Terraform
 ✅ Use interpolation for dynamic value extraction

Everything from scratch, in a way that’s easy to understand.

If this helped you — please share and follow for more DevOps goodness!

By Raees Qazi
 DevOps Engineer | Learner | Mentor | Creator