What is 12 Factor App ?

 The "12 Factor App" methodology is a set of best practices designed to guide developers in building scalable, resilient, and maintainable web applications. Originally introduced by engineers at Heroku, these principles have become foundational in modern application development. Let's delve into each factor:

1. Codebase: Each application should have a single codebase tracked in version control, enabling collaboration and ensuring consistency across environments.

2. Dependencies: Explicitly declare and isolate dependencies, such as libraries and frameworks, to maintain consistency and reproducibility across development, staging, and production environments.

3. Config: Store configuration settings, such as database credentials and API keys, as environment variables to facilitate portability and configuration management without modifying code.

4. Backing services: Treat backing services (databases, message queues, caching systems) as attached resources that can be attached or detached dynamically, enabling easy scaling and resilience.

5. Build, release, run: Separate the build, release, and run stages of the application lifecycle, enabling automation, consistency, and reproducibility in deployment processes.

6. Processes: Execute the application as one or more stateless processes that share nothing, facilitating horizontal scalability, fault tolerance, and graceful handling of failures.

7. Port binding: Export services via a well-defined port binding mechanism (e.g., HTTP) to enable easy communication between components and compatibility with modern deployment platforms.

8. Concurrency: Scale out via the process model, allowing multiple instances of the application to run concurrently and handle increased workload without introducing complexity or contention.

9. Disposability: Design applications to be disposable, allowing for quick startup and shutdown, graceful degradation, and seamless replacement of instances to facilitate rapid scaling and fault recovery.

10. Dev/prod parity: Strive for parity between development, staging, and production environments, ensuring consistency in configuration, dependencies, and behavior to minimize issues and improve reliability.

11. Logs: Treat logs as event streams, capturing application output and events in a structured format, facilitating real-time monitoring, analysis, and debugging across distributed systems.

12. Admin processes: Run administrative tasks, such as database migrations and one-time scripts, in a similar environment and with the same tools used in production to minimize discrepancies and ensure reliability.

Adhering to the principles outlined in the 12 Factor App methodology empowers developers to build robust, scalable, and maintainable applications that are well-suited for modern cloud-native environments. By embracing these best practices, teams can streamline development workflows, improve deployment agility, and deliver high-quality software that meets the demands of today's digital landscape.