Last weekend I built a small CLI tool to compare Spring Boot config files across profiles. Then I ran it against a handful of well-known open-source Spring Boot projects on GitHub. The results were uncomfortable. Not because the code was bad. The code was fine. But in project after project, application-prod.yml quietly diverged from what the developers intended — and none of it would have shown up in a code review or failed a single test. Here's what I found, and why it matters. What is config drift? Spring Boot lets you define configuration per environment using profile files: application.yml ← defaults application-dev.yml ← overrides for development application-staging.yml ← overrides for staging application-prod.yml ← overrides for production Enter fullscreen mode Exit fullscreen mode Config drift happens when a value in one profile diverges from the others in a way that wasn't intentional.…