Horizon dashboard query

Hi everyone! I need a guide or advice or anything. I am administering a private cloud in openstack. As I am using the Horizon dashboard for the VM provisioning and administering activities. But the users are sending requests in mail and creating the VMs for them. can we make workflow automation for the request and approval and provisioning automatically in the Horizon dashboard on approval? Has anyone already done /have idea on these kinds of solutions for your openstack cloud ??. Is there some kind of documentation that could help me?. Any guidance much appreciated, where to start, what to refer and which tool/programming language best if I need to code from scratch. thanks in advance. Krish