(Disclaimer; I'm an Atlassian employee.)
Bamboo is still the recommended solution for on-premises installations. The requirements and practicalities of OP vs cloud CI are different enough that they warrent different approaches.
That said, Bamboo supports scaling builds using AWS, and has 1st-class support for Docker-based build/test setups. I gave a talk on this at Atlassian's Summit last year if this sounds useful: http://summit.atlassian.com/videos/build/docker-continuous-i...