Google Apps Marketplace declare scopes multiple times?

Question

I'm trying to build a Google Apps Marketplace App using the new APIs only available through OAuth2. We already have an app using the old APIs, but I'm having trouble figuring out how to have the same flow with OAuth2.

In our old app, the domain administrator would install the app and give it permissions. Then, we could just make requests using our app's id/secret without user interaction. (2-legged OAuth)

How would I do this with OAuth2? None of the flows described here sound like what I'm looking for.

Answer 1

I'm also having hard times to find out to get this new OAuth2 login up and running. You will have to use service accounts to make requests on behalf of the user. Documentation is here: https://developers.google.com/accounts/docs/OAuth2ServiceAccount

I did not yet manage to get the flow working without each user being prompted again, but this most likely is because I need offline access:

Google Apps Marketplace SDK + Domain-wide OAuth 2 SSO