Scaling out JavaScript Monorepos with Yarn Workspaces

Monorepos are gaining popularity in the JavaScript community due to their ability to host multiple applications within a single repository, enhancing collaboration and simplifying repository management. Tools like Yarn, with its version 2 release in 2020, have introduced features beneficial for monorepos, such as zero installs, plug'n'play dependency management, and workspaces to efficiently manage dependencies across projects. This text explores setting up a monorepo using Yarn workspaces and Semaphore's CI/CD platform, focusing on creating a pipeline that only builds and tests recently changed applications, thus saving time and resources. The setup involves organizing JavaScript applications into workspaces, utilizing Yarn's package management features, and configuring Semaphore for change-based execution to optimize the build process. The guide also covers integrating multiple applications with conditional execution based on changes, ultimately facilitating a streamlined, automated continuous deployment process.