Google Compute Engine instances should be provided with a set of permissions in the form of a serviceAccounts field at the moment of node creation. Missing to do so may block the instance from being able to serve its intended purpose.
PR 110 introduced a serviceAccounts field in the NewInstance class, but the support is incomplete. Some of the wiring is still missing and a way to propagate these values.
This could probably be easily done by extending GCETemplateOptions as previously suggested.
Relates to these comments.