I don't think what you are describing is possible, but if you start from scratch, I believe you can create an image from the running instance, and then create an Autoscaling group, with instances based on that. These should be helpful:

https://docs.openstack.org/developer/heat/template_guide/ (https://docs.openstack.org/developer/...) http://superuser.openstack.org/articles/simple-auto-scaling-environment-with-heat/ (http://superuser.openstack.org/articl...) https://github.com/openstack/heat-templates/blob/master/hot/autoscaling.yaml (https://github.com/openstack/heat-tem...)