Workflow based VM provisioning for Openstack

List, 1. Does anybody using the workflow based front end tools for VM requisition, approval and provisioning for automating the requests from various users ? (The users can be or cannot be from backend AD/LDAP) 2. Or do we need to code from scratch to integrate such a mechanism(Do Horizon dashboard need to be customized for this workflow based approval and auto provisioning and de provisioning of VMs ? ) . Where to start ? Pls guide me on how to achieve this functionality for openstack IaaS cloud infrastructure. ( we are using Ussuri version). Thanks in advance, Krish