What is missing?

Current implementation is missing support for assigning system roles and subsequently querying such assignments:

• /v3/system - system roles API
  • api calls
• /v3/role_assignments - generic querying function supports filtering by system scope
  • schema
  • api call
  • implementation

If this is accepted, I will send PR for it.

Currently, we're missing this functionality in OpenStack Terraform provider. There's already an issue but, obviously, it requires gophercloud implementation first.