It can be. By default it is local. But it has protobufs interfaces (IIRC), so a distributed build farm would generate the grpc endpoints for their implementat

It can be. By default it is local. But it has protobufs interfaces (IIRC), so a distributed build farm would generate the grpc endpoints for their implementation and then you tell bazel on the command line (or via .bazelrc) the address of the build farm it can use. There's a couple of projects that implement the distributed/grpc part, the main one is https://github.com/bazelbuild/bazel-buildfarm https://github.com/bazelbuild/bazel-buildfarm