The 12 Factor App

This talk recaps the 12 Factor App methodology, which is a set of best practices for building scalable, maintainable, and portable web applications.

Introduction

• The Twelve-Factor App is a methodology for building software-as-a-service (SaaS) applications that ensures consistency, scalability, and ease of deployment across different environments.

I. Codebase

• Single Codebase:
  • One codebase tracked in version control, deployed in multiple environments.
  • If multiple codebases exist, the system is considered distributed rather than a single app.

II. Dependencies

• Explicit Declaration:
  • Dependencies must be explicitly declared and isolated.
  • The app should not rely on system-wide packages or tools, ensuring portability and consistency.

III. Config

• Environment-Based Configuration:
  • Configuration, including database and service handles, should be stored in the environment, making it easy to manage different deployment environments.

IV. Backing Services

• Treat as Attached Resources:
  • There should be no distinction between local and third-party services; all are treated as attached resources.

V. Build, Release, Run

• Separation of Stages:
  • The build, release, and run stages should be strictly separated to allow for rollbacks and better release management.

VI. Processes

• Stateless Processes:
  • The app runs as one or more stateless processes, with each process type handling different workloads.

VII. Port Binding

• Export Services via Port Binding:
  • The app should expose services by binding to a port and listening for requests, enabling seamless integration with web servers.

VIII. Concurrency

• Scale via Process Model:
  • Scale the app by assigning workloads to different process types, managed by the operating system’s process manager.

IX. Disposability

• Fast Startup and Graceful Shutdown:
  • The app should be disposable, capable of starting or stopping on short notice to ensure robustness.

X. Dev/Prod Parity

• Maintain Similar Environments:
  • Development, staging, and production environments should be kept as similar as possible to minimize gaps in time, personnel, and tools.

XI. Logs

• Treat Logs as Event Streams:
  • Logs should be treated as continuous event streams, with no concern for their routing or storage by the app itself.

XII. Admin Processes

• Run as One-Off Processes:
  • Administrative tasks should be run as one-off processes in the same environment as the app, using the same code and configuration.

For more details, visit 12factor.net.