Today, Amazon released their all-new CodeCommit service as part of the Amazon Web Services family. CodeCommit is a Git repository hosting service built for scalability and reliability, helping to securely store encrypted versions of your code, binaries, and configuration related to your products and cloud infrastructure.
They've put together a guide on integrating AWS CodeCommit with Review Board that you can follow if you're wanting to give this service a try. It'll walk you through deploying a Review Board server, setting up access to CodeCommit, linking your repository, and posting changes for review.
Currently, setup requires maintaining an in-sync clone of your repository on the Review Board server. We're aiming to work with the CodeCommit team to help bring direct support for hosted CodeCommit repositories to a future release of Review Board and RBCommons.