Continuous Integration for Monorepos

Monorepos, which are large code repositories encompassing multiple projects, often challenge conventional continuous integration due to their complex workflows and frequent updates. Semaphore uniquely supports monorepos by introducing the change_in function, which allows for change-based execution by skipping pipeline jobs for code that hasn't been altered, reducing unnecessary resource expenditure. This function enables targeted execution within a monorepo by monitoring specific files or folders for changes and updating only the relevant parts of the pipeline. The article provides a detailed guide on setting up monorepo workflows using Semaphore, illustrating with examples from the semaphore-demo-monorepo project, which includes services written in different programming languages. It also discusses the use of change_in for automatic promotions and parametrized promotions to optimize pipeline efficiency and maintain a unified release process across multiple projects within a monorepo.