Packer-Cn/website/source/partials/builder/amazon/common/_BlockDevice.html.md

These will be attached when booting a new instance from your AMI. Your options here may vary depending on the type of VM you use.

Example use case:

The following mapping will tell Packer to encrypt the root volume of the build instance at launch using a specific non-default kms key:

"launch_block_device_mappings": [{
		"device_name": "/dev/sda1",
		"encrypted": true,
		"kms_key_id": "1a2b3c4d-5e6f-1a2b-3c4d-5e6f1a2b3c4d"
}]

Documentation for Block Devices Mappings can be found here: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/block-device-mapping-concepts.html

These mappings give you control over either the volumes generated for the Packer build via launch_block_device_mappings, or the volumes that Packer will save with the artifact AMI via ami_block_device_mappings.