Picking EC2 instance types

It’s common to want to test infrastructure code that deploys EC2 instances into AWS. There are many different instance types, but not all instance types are available in all regions or availability zones (AZs). For example, t3.micro is sometimes available only in newer AZs, while t2.micro is sometimes only available in older AZs. If you are testing code that needs to deploy a “small” instance across many regions, this can make it tricky to know which region to pick.

To help work around this problem, Terratest includes GetRecommendedInstanceTypeContext, a Go function that helps you pick a recommended instance type.

GetRecommendedInstanceTypeContext

GetRecommendedInstanceTypeContext takes in an AWS region and a list of EC2 instance types and returns the first instance type in the list that is available in all Availability Zones (AZs) in the given region. If there’s no instance available in all AZs, this function exits with an error.

Example usage:

ctx := t.Context()

aws.GetRecommendedInstanceTypeContext(t, ctx, "eu-west-1", []string{"t2.micro", "t3.micro"})
aws.GetRecommendedInstanceTypeContext(t, ctx, "ap-northeast-2", []string{"t2.micro", "t3.micro"})