The twelve factors


In the modern era, software is commonly delivered as a service: called web apps, or software-as-a-service. The twelve-factor app is a methodology for building software-as-a-service apps that:

  • Use declarative formats for setup automation, to minimize time and cost for new developers joining the project;
  • Have a clean contract with the underlying operating system, offering maximum portability between execution environments;
  • Are suitable for deployment on modern cloud platforms, obviating the need for servers and systems administration;
  • Minimize divergence between development and production, enabling continuous deployment for maximum agility;
  • And can scale up without significant changes to tooling, architecture, or development practices.

The twelve-factor methodology can be applied to apps written in any programming language, and which use any combination of backing services (database, queue, memory cache, etc).

The Twelve Factors


One codebase tracked in revision control, many deploys


Explicitly declare and isolate dependencies


Store config in the environment

Backing services

Treat backing services as attached resources

Build, release, run

Strictly separate build and run stages


Execute the app as one or more stateless processes

Port binding

Export services via port binding


Scale out via the process model


Maximize robustness with fast startup and graceful shutdown

Dev/prod parity

Keep development, staging, and production as similar as possible


Treat logs as event streams

Admin processes

Run admin/management tasks as one-off processes