Spring Boot Done Right: Lessons From a 400-Module Codebase

Most Spring Boot tutorials show you a controller, a service, a repository, and call it a day. That’s fine for a TODO app. But what happens when your application grows to 400 modules, gets deployed at thousands of organizations worldwide, and needs to let operators swap out nearly any component without touching your source code? That’s the problem Apereo CAS solves every day. CAS — the Central Authentication Service — is an identity and single sign-on platform that’s been running in production for over 20 years. Its current incarnation is a Spring Boot 3.