fifteen-factor-applisted

# Fifteen-Factor App Methodology ## Overview The Fifteen-Factor App methodology extends the original Twelve-Factor App principles (created by Heroku in 2012) with three additional factors essential for modern cloud-native applications: API First, Telemetry, and Security. This methodology provides architectural principles and guidelines for building software-as-a-service applications that are: - **Performant** - Optimised for speed and efficiency - **Scalable** - Designed for horizontal scaling without significant changes - **Manageable** - Easy to deploy, monitor, and maintain - **Resilient** - Robust against failures with graceful degradation ## When to Apply This Methodology Apply the Fifteen-Factor principles during: 1. **Architecture Planning** - When designing new applications or microservices 2. **PRP/PRD Creation** - When documenting technical requirements and specifications 3. **Code Reviews** - When evaluating whether implementations follow best practices 4. **Migration Planning** - When modernising legacy applications for cloud deployment 5. **Technical Debt Assessment** - When identifying architectural improvements ## The Fifteen Factors at a Glance | Factor | Principle | Key Concept | |--------|-----------|-------------| | I. Codebase | One codebase, many deploys | Single repo per app, version controlled | | II. Dependencies | Explicitly declare and isolate | No implicit system-wide packages | | III. Config | Store in environment | Never hardcode configur