If your project's repository is hosted on GitHub, you can use Travis CI for your automated builds. Travis CI (https://travis-ci.org) is an open source hosted continuous integration system, and is free to use for public repositories. There is a paid plan for private repositories, but in this book we will only look at the free option.
Travis detects when a new commit is pushed to the repository and starts a new build automatically. By default, Travis builds all branches, not just the master branch. It also builds pull requests automatically; a useful feature for open source projects.
Because of how Travis works internally, you cannot configure the build server itself. Instead, you need to create a configuration file that contains all the information that Travis needs to build your app or library.