Open source software, where code is freely available for modification
and redistribution, is a powerful method for producing high-quality
software. In the area of build-engineering, where developers work to
build and deploy complex software, there are a plethora of open-source
tools. Why? Building software at scale is a hard problem. In 2015, the
number of lines of code that spans Google's web services was estimated
at 2 billion lines of code. This is in a single repository, with 25,000
active developers. What do you do to manage this complexity? How do you
approach trying to build software faster at this scale?
We present an overview of what open source software is and why it is important. As an example, we describe Codethink's open source efforts around the REAPI (remote execution API) which is an open source API for building binaries in a remote system. Finally, we'll discuss future directions, including how anyone can get involved in our open source projects!