Many FOSS project maintainers are operating extensive CI systems to ensure quality, stability, and rapid delivery of their software. Homebrew, the package manager beloved by macOS developers, is one such project. In this session, we’ll dive into the evolution of Homebrew’s CI pipelines for pull request validations, integration testing, and full regression tests for releases.

Each tier of CI and test automation comes with its own unique challenges. With a variety of pull requests coming in across the Homebrew and Workbrew repositories, CI pipelines need to be fast and efficient. While a pull request may look simple on the surface, complexity often arises in the testing phase, as a modification may need to be tested against everything that runs on a particular package. We’ll explore how Homebrew balances scalability and reliability across its CI landscape by utilizing open source virtualization and orchestration technology tailored to developers on macOS.