You should have a look at Scalingo, (disclaimer, I'm the CTO).
We've a git push similar workflow, as well as a github integration to create temporary environment per Pull Request, so potentially per branch. There is a fully-featured command line client, everything you can achieve graphically, you should be able to do it with the CLI. Auto-scaling is coming in the coming months. We're also based in France if data locality/nationality of the provider is important to you.
Would you be ok to exchange a little more in a call, or through emails? We'd be glad to discuss your needs.
You can also give a chance to Scalingo (https://scalingo.com), a French player, Heroku-like, based on 3DS OUTSCALE's infrastructure.
I've tried Google Cloud and found it extremely confusing, especially App Engine. It's poorly documented and deploying an app can take more than 30 minutes for reasons I don't know. I also couldn't figure out the exact pricing and the steps to using your own domain name didn't work. I spent a lot of time on it and eventually gave up. Next I tried Heroku and found it to be much easier to understand and use. Scalingo is an alternative to Heroku, cheaper but they don't nearly have as many add-ons as Heroku.