Auto Scaling groups should use multiple instance types in multiple Availability Zones

Severity: Medium

Resource Types: AWS::AutoScaling::AutoScalingGroup

Description

This control checks whether an Amazon EC2 Auto Scaling group uses multiple instance types. The control fails if the Auto Scaling group has only one instance type defined.

You can enhance availability by deploying your application across multiple instance types running in multiple Availability Zones. Security Hub recommends using multiple instance types so that the Auto Scaling group can launch another instance type if there is insufficient instance capacity in your chosen Availability Zones.

Remediation

For detailed instructions on how to modify the metadata response hop limit for an existing launch configuration, see Modify instance metadata options for existing instances in the Amazon EC2 User Guide for Linux Instances and Modify instance metadata options for existing instances in the Amazon EC2 User Guide for Windows Instances.