Packer kms_key_id for ebs volumes

Question

I'm trying to use packer to build an AMI with encrypted EBS volumes (but not an encrypted root volume). The packer documentation says:

kms_key_id (string) - The ID of the KMS key to use for boot volume encryption. https://www.packer.io/docs/builders/amazon-ebs.html#kms_key_id

If I supplied a kms_key_id and mark the desired ebs volumes' ami_ and launch_block_device_mappings as encrypted, will packer use that kms key? Or will a default CMK key be used?

Answer 1

Quickly looking into the code it looks like kms_key_id is only used for the encryption of the boot volume. Other block_device_mappings with "encrypted": true will be encrypted with the default EBS KMS key.