Enforcing Modularity in Rails Apps with Packwerk - Shopify

This post introduces Packwerk, a new open-source tool for enforcing code boundaries in Rails applications. It details the problem of low cohesion and high coupling in large Rails monoliths, explores existing boundary enforcement solutions (private_constant, gems, tests, Modulation), and explains why a custom solution was necessary. Packwerk enforces dependency and privacy violations by analyzing constant references between packages.