The Twelve Factors App is a methodology that a web application should follow to be able to easily deploy and scale on today’s SAAS platform like Heroku. This methodolgy is announced by the Heroku Founder Adam Wiggins. The content is the based on their experience of deploying millions of applications.

When I first saw this declaration, I just feel that this might be extract from rails and herokus best practices, but actually this declaration is more then practices but a methodology to improve the maintainbility and scalability of web application. so I like to share Heroku engineer’s slide about 12 factors app:

The Twelve-Factor App

I. Codebase

One codebase tracked in revision control, many deploys

II. Dependencies

Explicitly declare and isolate dependencies

III. Config

Store config in the environment

IV. Backing Services

Treat backing services as attacked resources

V. Build, release, run

Strictly separate build and run stages

VI. Processes

Execute the app as one or more stateless processes

VII. Port binding

Export services via port binding

Concurrency

Scale out via the process model

IX. Disposability

Maximize robustness with fast startup and graceful shutdown

X. Dev/prod parity

Keep development, staging, and production as similar as possible

XI. Logs

Treat logs as event streams

XII. Admin processes

Run admin/management tasks as one-off processes