Who owns calendars created by service account via Google Calendar API and how can they be shared?

Question

Let's say I have a Google account [email protected] with project project-1 (configured as Google App Engine application in Google Developer Console) and a service account with e-mail address [email protected] that belong to it.

I know how to use this service account to create a calendar and manipulate its entries programmatically: I use the Google APIs Client Library (Java version, with service account´s credentials) to invoke Google Calendar API inside my Google App Engine application and it does just that. However any such created calendars seem to be distinctly owned by the service account, not by my englobing Google account. I conclude this from the following observations:

• When I view my Google account's calendar in the Google Calendar UI, none of the programmatically created calendars show up under My calendars.
• When I try to access such a calendar by issuing Other calendars | Add a friend´s calendar and with the service account´s email-address, I can send off the request, but it never gets answered (presumably because the service account's e-mail address isn't a "real" e-mail address).
• When I'm creating calendars programmatically, I don't set CalendarListEntry#hidden, so the default false should apply.

So my question is this: How can I access calendars and calendar entries that were created programmatically with Google Calendar API (and a Java client in my case) in the normal Google Calendar Web UI. E.g., can the service account share its calendars with its owning Google account, or can I directly manipulate the Google account's calendars with its service account credentials in the UI.

I realize there are some previous questions on the same topic, but they haven't helped to solve the mystery for me so far.

Answer 1

You will have to programmatically share the calendar created by the service account. The calendars are owned by the service account.

What you tried :

• the calendars don't show up in your account because you have no right to access them, even though you are the appengine admin.
• entering the e-mail address of the service account does not show up the calendar in the UI because the e-mail address of the service account is not the e-mail address of the calendar. One service account could create multiple calendars.

Share the calendar programmatically with your account, log the calendar unique id and then enter it in the UI.

Answer 2

According to the (outdated) documentation, you have to call .setServiceAccountUser("[email protected]") and the event will show up on that user's Calendar.

https://developers.google.com/identity/protocols/OAuth2ServiceAccount#authorizingrequests

Delegate domain-wide authority
If you have delegated domain-wide access to the service account and you want to impersonate a user account, specify the email address of the user account with the setServiceAccountUser method of the GoogleCredential factory. For example:

GoogleCredential credential = new GoogleCredential.Builder()
    .setTransport(httpTransport)
    .setJsonFactory(JSON_FACTORY)
    .setServiceAccountId(emailAddress)
    .setServiceAccountPrivateKeyFromP12File(new File("MyProject.p12"))
    .setServiceAccountScopes(Collections.singleton(SQLAdminScopes.SQLSERVICE_ADMIN))
    .setServiceAccountUser("[email protected]")
    .build();

It has to be a service account for a GSuite domain, and you have to enable GSuite Domain-wide Delegation.