The Twelve-Factor App

The Twelve-Factor App is a set of rules for building web apps and services that run well on cloud platforms. Engineers at Heroku wrote it in 2011 after watching thousands of apps deploy, and it still describes what platforms like Kubernetes expect from your code today.

An app that follows the twelve factors:

• deploys the same way everywhere, from a laptop to production;
• scales by running more copies, not by buying a bigger server;
• survives restarts, because no process holds anything it can't lose;
• lets you ship often, because development and production barely differ.

#One app, all twelve factors

Here is a single web app, from the laptop it's written on to the database it talks to. Pick a factor to see which parts of the app it's about, or press Play all to go through them in order.

1Codebase2Dependencies3Config4Backing services5Build, release, run6Processes7Port binding8Concurrency9Disposability10Dev/prod parity11Logs12Admin processes

1.Codebase

One app lives in one repository. Every environment runs a build of that same code, just at different commits.

Read Codebase

#The factors, one page each

The numbers are the order the methodology lists them in. You don't have to read them in order, but the first five build on each other.

#Check yourself

Two services share one git repository. Which factor does that break?Think of the answer, then click to flip

The original text is at 12factor.net.