Disk size is larger than image size when creating Compute Engine VM in Google Cloud Deployment Manager Template

I'm using a Google Cloud Deployment Manager Template to create a Compute Engine VM instance in Google Cloud. However, I'm encountering a warning during the deployment process: "Disk size: '60 GB' is larger than image size: '10 GB'." The deployment is completed successfully, but I want to understand the implications of this warning and how to address it.

Here is my Deployment Manager template code:

def generate_config(context):
    COMPUTE_URL_BASE = "https://www.googleapis.com/compute/v1/projects"
    SOURCE_IMAGE=f"{COMPUTE_URL_BASE}/debian-cloud/global/images/family/debian-11"
    DISK_SIZE=60
    
    VM_MACHINE_TYPE = "g1-small"
    REGION = "europe-west2-b"
    PROJECT_ID = context.env["project"]
    VPC_NETWORK="default"
    SUBNETWORK="default"


    VM = {
        "name": "dinesh-vm",
        "type": "compute.v1.instance",
        "properties": {
            "zone": REGION,
            "machineType": f"zones/{REGION}/machineTypes/{VM_MACHINE_TYPE}",
            "disks": [{
                "boot": True,
                "autoDelete": True,
                "initializeParams": {
                    "sourceImage": SOURCE_IMAGE,
                    "diskSizeGb": DISK_SIZE,
                },
            }],
            "networkInterfaces": [{
                "network": f"{COMPUTE_URL_BASE}/{PROJECT_ID}/global/networks/{VPC_NETWORK}",
                "subnetwork": f"{COMPUTE_URL_BASE}/{PROJECT_ID}/regions/europe-west2/subnetworks/{SUBNETWORK}",
                "accessConfigs": [{
                    "name": "External NAT",
                    "networkTier": "PREMIUM",
                    "type": "ONE_TO_ONE_NAT",
                }],
            }]
        }
    }
    return {"resources": [VM]}

During the deployment process, I receive the following warning:

dineshsonachalam@macbook compute_engine % gcloud deployment-manager deployments create dinesh-vm --template vm.py
The fingerprint of the deployment is b'ZmY2S4OqjswQhQfT_=='
Waiting for create [operation-1684]...done.                                                                       
WARNING: Create operation operation-1674932237 completed with warnings:
---
code: EXTERNAL_API_WARNING
data:
- key: disk_size_gb
  value: '60'
- key: image_size_gb
  value: '10'
message: "Disk size: '60 GB' is larger than image size: '10 GB'. You might need to\
  \ resize the root repartition manually if the operating system does not support\
  \ automatic resizing. See https://cloud.google.com/compute/docs/disks/add-persistent-disk#resize_pd\
  \ for details."

NAME       TYPE                 STATE      ERRORS  INTENT
dinesh-vm  compute.v1.instance  COMPLETED  []
dineshsonachalam@macbook compute_engine % 

I would like to understand the implications of this warning and how I can address it.
Any guidance or insights would be greatly appreciated. Thank you!

Edit:

It seems like if you're using a public image, Compute Engine automatically resizes the boot disks.

dineshsonachalam@macbook Desktop % gcloud compute images list | grep -i "debian"
NAME                                                  PROJECT              FAMILY                             DEPRECATED  STATUS
debian-10-buster-v20230510                            debian-cloud         debian-10                                      READY
debian-11-bullseye-v20230509                          debian-cloud         debian-11                                      READY

Reference: https://cloud.google.com/compute/docs/disks/resize-persistent-disk

If automatic resizing is supported, why am I still receiving the warning?

This is just a warning and we can ignore it as per your discretion. If you create a disk larger than the size of the image in GCP, the usable space will only be equal to the size of the image. For example, if you create a disk of 30GB using one of the default images in GCP, which has a size of 10GB, the usable space will still only be 10GB. By following this official doc1 and Doc2 you can resize the disk size. To avoid the warning, you can revise your template to use disk size >= 200GB

> As per @Johnhanley comments The Debian images support automatic
> resizing of the root file system. You can Go through the blog By
> John Hanley on October 27th, 2018 in Debian, Google