feat: `enable_nested_virtualization` on ephemeral instance

[guiadco]

Description

Actually, the Google Compute Builder is only able to create a image with nested licenses to build a Google Compute image but in my case, I need to use Packer in Packer to create a legacy image (qcow2) inside the Google Compute Builder.

But we get this error:

qemu-system-x86_64: failed to initialize KVM

The Google Compute Builder doesn't be able to use the enable_nested_virtualization on ephemeral instance.

Use Case(s)

• for factory image builder, It could be interesting to activate this option to be able to craft legacy image like raw or qcow2 instead of creating a custom image with the license activated:
  • And after using terraform to start a new VM with this image to be able to craft the artifacts wanted
  • Or using the special image with the Google Compute Builder.

It force to maintain a special image apart this section whereas Google Compute Engine have a recommended option for that.

Potential configuration

It could be great to use like terraform:

  advanced_machine_features {
    enable_nested_virtualization = true
  }

Potential References

• https://cloud.google.com/build/docs/building/build-vm-images-with-packer
• https://cloud.google.com/compute/docs/instances/nested-virtualization/enabling

Recommended. Enable nested virtualization directly on a new or existing VM by setting the enableNestedVirtualization field to true while creating the VM or by updating the VM. 

This is the recommended method because it doesn't require that you create a custom image or use the special license key.