protoc

https://github.com/Tripwire/protoc-gem

This gem includes protoc, the protobuf compiler, binaries for Linux, Mac, and Windows. It installs a executable shim called `protoc` that picks the right one to run on your platform. You can use this gem to ensure that you have a protoc of the version you need. By using this gem, you will not need to manually install the right protoc on your hosts. The pre-built linux protoc binaries are not compatible with all systems. For this reason the protobuf source code is included in this gem, and a new protoc binary is built upon gem installation when the pre-built one does not function.