Google Cloud Deployment Manager and resources changes

I would like to deploy an application in Google Cloud. It would require the following Google Cloud components:

• Google Container Engine (so I can run an application inside Kubernetes cluster)
• Google Compute Engine persistent disk (attached to the application Kubernetes pods)
• Kubernetes deployment (containing the application running in the pods)

I am evaluating Deployment Manager as a tool for infrastructure as code approach.

Currently I have found following issues:

Changing Container Engine cluster size

Change Container Engine cluster size in my Deployment Manager yaml template cannot be applied with:

gcloud deployment-manager deployments update <deployment-name> --config <deployment-config.yml>

fails with:

{"ResourceType":"container.v1.cluster","ResourceErrorCode":"400","ResourceErrorMessage":{"code":400,"message":"Invalid
JSON payload received. Unknown name \"cluster\": Cannot find
field.","status":"INVALID_ARGUMENT","details":[{"@type":"type.googleapis.com/google.rpc.BadRequest","fieldViolations":[{"description":"Invalid
JSON payload received. Unknown name \"cluster\": Cannot find
field."}]}],"statusMessage":"Bad
Request","requestPath":"https://container.googleapis.com/v1/projects/1013690875001/zones/europe-west1-b/clusters/dev-cluster"}}

Resizing persistent disk size

When I change the disk size in my template and try to apply the change (again with gcloud deployment-manager deployments update command) I am also getting an error:

No method found to update field 'sizeGb' on resource
'my-data-storage' of type 'compute.v1.disk'. The resource may need
to be recreated with the new field.

Question

I would think the operations describe above are ones of the most common one would apply to the environment and I am surprised they are not supported.

Am I misunderstanding how Deployment Manager should be used or it just doesn't provide the features I need? How should I manage such environment changes so they can be tracked in source control (instead of imperative commands like cloud compute disks resize)?