How do you reference the Volume IDs associated with ebs_block_device blocks?

The correct way to reference the Volume IDs associated with ebs_block_device blocks in Terraform is by using aws_instance.example.ebs_block_device.[*].volume_id. This syntax employs the splat operator ([*]), which allows you to collect values from a list of objects—in this case, from the ebs_block_device block associated with the specified aws_instance.

The ebs_block_device block is a list of attachments that are associated with the instance; each attachment can have a unique volume_id property. By using the splat syntax, you effectively obtain a list of all the volume_id values for each EBS block device, making it easy to reference all associated volume IDs at once.

Other options do not accurately represent how to reference these IDs. For instance, using aws_instance.example.volume_ids assumes a property that does not exist within the resource's schema. Likewise, naming conventions or property paths in options like instance.ebs_devices[*].volume_id and aws_instance.example.ebs.[*].vol_id do not directly correspond to the Terraform resource definitions regarding EBS block devices. Hence, they would lead to errors if used in a Terraform configuration.