Stratos: self-hostable billing & self-service portal for OpenStack

We've been building Stratos and just open-sourced it under AGPL-3.0. It's the layer that turns a raw OpenStack cloud into something you can hand to users and actually bill for. The gap it fills OpenStack already meters usage (Ceilometer/Gnocchi) and can even rate it (CloudKitty). But CloudKitty deliberately stops at "what would this cost" - no invoices, no payments, no taxes, no promotions, no customer-facing portal. So most operators bolt their own thing on top or pay for a closed-source product like Fleio