Maybe I don't understand what you're trying to achieve, but doesn't Gitlab CI fulfill that role? Your versioning system is essentially git. Branching is done trivially, rolling stuff back is running deploy pipeline from older branch or tag.
I'm talking about versioning infrastructure. So let's say you have a setup with a load balancer, three compute VMs and two database instances. You modify the config to make it three compute VMs and three database instances, but suddenly something goes wrong! Can you roll back your infrastructure easily?
