A character vector of scopes to request. Pick from those listed at https://developers.google.com/identity/protocols/oauth2/scopes.

For certain token flows, the "https://www.googleapis.com/auth/userinfo.email" scope is unconditionally included. This grants permission to retrieve the email address associated with a token; gargle uses this to index cached OAuth tokens. This grants no permission to view or send email. It is considered a low value scope and does not appear on the consent screen.

JSON identifying the service account, in one of the forms supported for the txt argument of jsonlite::fromJSON() (typically, a file path or JSON string).

Additional arguments passed to all credential functions.

An optional subject claim. Use for a service account which has been granted domain-wide authority by an administrator. Such delegation of domain-wide authority means that the service account is permitted to act on behalf of users, without their consent. Identify the user to impersonate via their email, e.g. subject = "user@example.com".