Create empty disk for Google Deployment Manager - google-cloud-platform

Question

I am try to creat a compute instance using Googles deployment manager. It has shall get two disk, one based on a boot image and a second that shall be blank. The blank disk will later on be formated and mounted correctly by salt stack. Deployment manager complains with "Source image must be specified." How do I create a second blank disk for a compute instance using deployment manager?
My compute-instance.jinja:
resources:
- type: compute.v1.instance
name: {{ env["deployment"] }}-{{ env["name"] }}
properties:
zone: europe-west1-c
machineType: zones/europe-west1-c/machineTypes/n1-standard-1
disks:
- deviceName: {{ env["deployment"] }}-{{ env["name"] }}
type: PERSISTENT
boot: true
autoDelete: true
initializeParams:
sourceImage: global/images/XXXXXXX
- deviceName: {{ env["deployment"] }}-{{ env["name"] }}-data
type: PERSISTENT
boot: false
autoDelete: true
initializeParams:
diskSizeGb: {{ properties["size"] }}
networkInterfaces:
- network: global/networks/default
accessConfigs:
- name: External NAT
type: ONE_TO_ONE_NAT

Answer 1

Solved by creating a separate resource for the disk using:
- type: compute.v1.disk
name: {{ env["deployment"] }}-{{ env["name"] }}-1-data
properties:
sizeGb: {{ properties["size"] }}
zone: europe-west1-c
Then refer to it from the compute-instance:
- deviceName: {{ env["deployment"] }}-{{ env["name"] }}-1-data
boot: false
autoDelete: true
source: $(ref.{{ env["deployment"] }}-{{ env["name"] }}-1-data.selfLink)

Answer 2

If you must supply the source image, you can create an image of an empty disk.
The downside of this, is that you will start paying (not much tough) for 10gb of image storage when your actually storing nothing.
gcloud compute disks create emptydisk --size 10GB
gcloud compute images create empty-disk-image --source-disk emptydisk
And then use it as the source image
- deviceName: {{ env["deployment"] }}-{{ env["name"] }}-data
type: PERSISTENT
boot: false
autoDelete: true
initializeParams:
sourceImage: projects/your-project-id/global/images/empty-disk-image
diskSizeGb: {{ properties["size"] }}