I wonder how / if Bazel will integrate wit Google Cloud Build. IMO that should be an end goal for a tool like Bazel. At a first glance, they are (highly) incompatible. 1. Bazel's statefulness is a core feature while GCB is stateless. 2. They both need to control things holistically to work (or you lose advantages otherwise).

So in order to benefit from the two, it would likely require GCB to work with Bazel natively and also to have some powerful state abstractions in order to optimize builds in a distributed fashion.