12 Factor App

This is the classic 12-factor methodology packaged as 51 rules across categories like config management, dependencies, and process architecture. You'd reach for it when containerizing apps, setting up CI/CD, or debugging why your staging environment behaves differently than production. The rules are prioritized from critical (codebase, dependencies, config) down to medium priority (logging, admin processes), which actually helps since not every factor matters equally on day one. Heavy emphasis on the boring fundamentals that actually matter: explicit dependencies, config in environment variables, stateless processes, and treating logs as streams. If you're building anything that needs to scale or run in multiple environments, these patterns will save you from a lot of self-inflicted pain.