The Twelve-Factor App

1. I. Codebase

   One codebase tracked in revision control, many deploys.

2. II. Dependencies

   Explicitly declare and isolate dependencies.

3. III. Config

   Store config in the environment.

4. IV. Backing services

   Treat backing services as attached resources.

5. V. Build, release, run

   Strictly separate build and run stages.

6. VI. Processes

   Execute the app as stateless processes.

7. VII. Port binding

   Export services via port binding.

8. VIII. Concurrency

   Scale out via the process model.

9. IX. Disposability

   Fast startup and graceful shutdown.

10. X. Dev/prod parity

    Keep development, staging and production similar.

11. XI. Logs

    Treat logs as event streams.

12. XII. Admin processes

    Run admin tasks as one-off processes.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.