Disclosure: I work at Zipline Games building out our cloud platform. We also have a cross platform game engine that lets you develop in lua. The engine is focused on mobile games so it runs on android, iOs and Chrome native client.

The cloud portion would make an excellent compliment to this since we host a mongo database for you, allow you to write and run your own lua code so you can develop your backend logic in the same language you build your game in. We also provide a set of RESTfull services for common game needs.

Check it out at http://getmoai.com/