Amazon EC2 Instance Metadata Service Now Supports Additional Fields for Improved Automation and Operability
We’ve introduced the following 5 fields to the instance metadata service: region, placement group name, partition number, host ID, and availability zone-ID. You can use these fields after launch or while your instance is running to understand your instance location. This is useful for populating the region for your AWS environment. Additionally, these fields help you identify your instance placement information within an availability zone.
Source:: Amazon AWS