Part 1: The Updated Template

Explanation

You already have a stack running from Lab 1.0 with a single EC2 instance. In this lab you will replace that template with a richer one that adds:

• A Parameter — so you can pass a custom value at deploy time
• An Elastic IP — a static public IP address attached to the instance
• Two Security Groups — one for SSH access, one for web traffic
• An updated EC2 instance — now referencing the security groups above

The file you will use is 1-ec2-with-sg-eip.yaml. Open it in your editor and read through it before uploading. Notice:

• The Parameters section at the top defines a SecurityGroupDescription input
• The EC2 instance now has a SecurityGroups property that references the two groups defined below it
• The !Ref function connects resources together — e.g. the Elastic IP references the instance

Key Concepts

• Parameters let you make templates reusable. Instead of hardcoding a value, you define a placeholder and provide the real value at deploy time.
• !Ref on a resource returns its ID or name depending on the resource type — this is how resources link to each other inside a template.
• Adding new resources to an existing template does not mean rebuilding everything from scratch — CloudFormation calculates only what changed.

Part 2: Start the Update

1. Open the CloudFormation Console and click on your running stack (EC2InstanceDemo).
2. Click Update in the top-right.