AWS CloudFormation: Create a VPC with EC2 Instance

AWS CloudFormation, an Infrastructure as Code service, includes a template made up of nine sections. Although made up of nine sections, the Resources section is the only one required. For this project we will be using Mappings, Resources, and Outputs. I’ve broken my template down to explain what is going on in each section, but if you want to jump straight to the full CloudFormation Template feel free to skip to the end.

Mappings

The Mappings section is basically a lookup table using key: value relationships. In this template the Amazon Machine Image is being mapped to its respective Region. Because I only have two Regions mapped, the Template is restricted to these two regions and would fail if launched outside of these Regions.

Resources

The Resources section includes all the AWS resources that you want to create in the stack.

1. For VPC, the template is assigning a CIDR of 10.0.0.0/16, Enabling DNS, and giving the VPC a tag of Name: LUIT Project.
2. For InternetGateway, the template is creating the IGW and assigning a tag of Name: LUIT Project.
3. For InternetGatewayAttachment, the template is attaching the IGW to the VPC. This is the first time in the template that we are using the intrinsic function Ref, which returns the value of the specified parameter or resource. As an example for this template for InternetGatewayId, we are referencing the InternetGateway Logical Id and for the VpcId, we are referencing the VPC Logical Id.

4. For PublicSubnet1, the template is creating a public subnet.

• For VpdId it’s using the Ref function to reference the VPC.
• For AvailabilityZone it’s using the Select function to select a single object from a list. In this case it is returning the first Availability Zone using the GetAZ function.