Resources
Core Idea
The twelve-factor app is a checklist for building services that deploy cleanly: one codebase, config outside code, stateless disposable processes, and dev/prod parity.
- State and config: declare dependencies, keep settings out of the code, treat backing services as attached resources.
- Process model: expose the app by port binding, scale by adding processes, start fast and shut down gracefully.
- Ops hygiene: separate build, release, and run; keep dev and prod alike; treat logs as event streams; run admin tasks as one-off processes.
- Codebase:
Have one place to keep all your code, and manage it using version control like Git Hooks. - Dependencies:
List all the things your app needs to work properly, and make sure they’re easy to install. - Config:
Keep important settings like database credentials separate from your code, so you can change them without rewriting code. - Backing Services:
Use other services (like databases or payment processors) as separate components that your app connects to. - Build, Release, Run:
Make a clear distinction between preparing your app, releasing it, and running it in production. - Processes:
Design your app so that each part doesn’t rely on a specific computer or memory. It’s like making LEGO blocks that fit together. - Port Binding:
Let your app be accessible through a network port, and make sure it doesn’t store critical information on a single computer. - Concurrency:
Make your app able to handle more work by adding more copies of the same thing, like hiring more workers for a busy restaurant. - Disposability:
Your app should start quickly and shut down gracefully, like turning off a light switch instead of yanking out the power cord. - Dev/Prod Parity:
Ensure that what you use for developing your app is very similar to what you use in production, to avoid surprises. - Logs:
Keep a record of what happens in your app so you can understand and fix issues, like a diary for your software. - Admin Processes:
Run special tasks separately from your app, like doing maintenance work in a workshop instead of on the factory floor.