How does the Google Apps Marketplace SSO requirement work? - google-apps-marketplace

Question

We're trying to figure out how to submit to the marketplace, but are not sure what we need to do to alter our existing signup flow to accomodate the SSO requirement
Our app was not originally built to be a marketplace app so our signup flow is built for individual users. We are already following the OAuth2 flow as outlined on this documentation page. However, its not clear to me how this works for an entire org when installing from the context of a marketplace app.
Does the admin grant access to all the individual scopes we currently request for the entire org at once? Is there need for some sort of service account or something since we currently are requesting offline access? I'd like to understand what changes we need to make to our server's signup flow in or whether it is just a scope / manifest mismatch.
We currently request the following scopes from an individual user when signing up.
['email', 'profile' ,'https://mail.google.com/', 'https://www.googleapis.com/auth/calendar'],
Exact questions are...
What (if anything) do we need to do to alter our current individual-focused signup flow to accommodate a Google Apps Admin signing up their whole domain?
What scopes do we need to in our Google Apps Admin listing and how do they relate to the scopes we currently request from individuals?

Answer 1

There are not so many changes if you are already using three legged OAuth2.
The first change would be in you project in the developer console. There you need to enable the Marketplace SDK and make the necessary configurations. Here you will add the scopes that your app will request and those are the scopes that the admin will see when installing the app.
The admin will see the scopes your app is requesting, and he will decide if it's ok to install the application in the domain. If it is approved, then yes, the admin would grant access to the entire domain.
Offline access is part of the Oauth flow, after you receive the refresh token, you can continue refreshing the access token without having the user to grant access again.
It is not necessary to have a service account. The service account has two purposes:
To manage information related to the application. In this case the service account can have access to it's own drive to store and retrieve information that is related to the app functionality.
Impersonation of users. When using domain delegation of authority, you can use a service account to impersonate any user in a domain and act on it's behalf to make API calls.
To deploy your app, you also have to create a new project in the Chrome Web Store, with a manifest for Marketplace.
To answer your questions:
It's not necessary that you modify your current oauth flow. The admin will install the app in the domain, but when a user access to the app, the process for authentication is the same as individual.
The scopes in your Marketplace SDK configuration should match the scopes your app will use. This is mostly for security reasons, it wouldn't be safe if you install an app with some scopes and then the app uses different scopes.
You can try your app before actually deploying it by adding trusted testers in the chrome web store dashboard or in the Console API configuration. This way you can check if your flows and all the configurations were done correctly.
Hope this helps. Let me know if you have more questions.