Stackdriver Provisioning: GCE Service Account

Hello -
I’m attempting to follow the doc example listed here:
http://docs.grafana.org/features/datasources/stackdriver/#configure-the-datasource-with-provisioning
for provisioning a datasource using a GCE service account as authentication. I’m using Ansible and can successfully use a JWT (key file) however I would like to switch to using a GCE Service Account. API access is enabled, Service Account has correct perms, assigned to instance, etc. When I use the example, e.g.

test_data_source:

  - {
    name: Stackdriver,
    type: stackdriver,
    access: proxy,
    jsonData: {
      authenticationType: gce
    },
  }

I simply get the following error in the Grafana ‘edit datasource’

Stackdriver: Unauthorized: 401. Request is missing required authentication credential. Expected OAuth 2 access token, login cookie or other valid authentication credential. See https://developers.google.com/identity/sign-in/web/devconsole-project.

Is there something in the doc that is implied that I am missing? Any help would be appreciated.

I realized this was fixed in 5.4.0-beta1: https://github.com/grafana/grafana/issues/13669