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Who is This Post for?

Although I assume you have some initial knowledge about AWS, I’ll try to explain all the used resources briefly and provide links to the related AWS documentation for further information. Also, if you’re new to Terraform, don’t worry! You can use this post as an entry point. Just follow the process with me and check the provided links to Terraform documentation if you need to dive deeper into the concepts.

Why Terraform?

Because I love it! It’s so simple and developer-friendly but powerful, modular, flexible, and extendable. I’ve spent hundreds of hours configuring and deploying cloud resources on AWS using CDK and CloudFormation. But in my personal opinion, Terraform shines in the IaC muddy ground! Terraform’s declarative approach means you describe the desired state of your infrastructure, and it figures out how to make it happen.

What is an AMI?

An Amazon Machine Image (AMI) is essentially a blueprint for an EC2 instance. It includes everything needed to launch a server: the operating system, installed software, configurations, and optional application code. Instead of setting up a fresh instance manually each time, you can use an AMI to deploy identical instances quickly and reliably. Think of it like making a pizza at home.

Why Build a Custom AMI?

When launching an EC2 instance, you have three main options: Start from scratch – Use a bare Linux AMI, launch an instance, SSH in, and manually install and configure everything. This gives you full control but is tedious and time-consuming.

What is Packer?

Packer, created by HashiCorp, is a tool that automates machine image creation. Instead of manually setting up an instance and then taking a snapshot, Packer does everything for you. You define a template (in JSON or HCL), and Packer spins up a temporary server, installs and configures everything, then saves the final golden image as an AMI.