The Twelve-Factor App methodology is a set of best practices for building modern, scalable, and maintainable software applications. It was created by Heroku co-founder Adam Wiggins in 2011 and has since become a widely adopted standard for developing cloud-native applications.
The Twelve-Factor App methodology is designed to help developers build applications that are easy to deploy, scale, and maintain. It provides a set of guidelines that cover everything from codebase organization to deployment strategies. By following these best practices, developers can create applications that are more reliable, scalable, and maintainable.
The Twelve Factors
- Codebase
- Dependencies
- Config
- Backing Services
- Build, release, run
- Processes
- Port binding
- Concurrency
- Disposability
- Dev/prod parity
- Logs
- Admin processes
1. Codebase
Have one place that is the source of truth for your codebase. This is typically a version control system like Git.
The code versioned in the repository should be the same code that is running in production. With features that will be deployed to other environments.
2. Dependencies
Ensure all dependencies are declared and isolated. This means that all dependencies should be explicitly declared and managed in a way that is isolated from other dependencies. This can be done using a package manager like npm or pip or composer.
3. Config
Ensure that your applications config can be changed by enivronment. This means that your application should read its configuration from environment variables rather than hardcoding them in the codebase.
4. Backing Services
Use other services as backing services. This means that your application should treat services like databases, caches, and message queues as attached resources that can be swapped out easily.
5. Build, release, run
Separate the build, release, and run stages of your application. This means that your application should have a clear separation between the build process, the release process, and the run process.
6. Processes
Run your application as one or more stateless processes. This means that your application should be designed to run as one or more stateless processes that can be easily scaled up or down.
This is important in cloud-native applications because it allows you to easily scale your application horizontally by adding more instances of your application.
7. Port binding
Expose services via port binding. This means that your application should expose services via a port binding mechanism that allows other services to connect to it.
8. Concurrency
Scale out via the process model. This means that your application should be designed to scale out by adding more instances of your application rather than scaling up by adding more resources to a single instance.
The ability to add async workers to your application is also important for handling background tasks.
9. Disposability
Maximize robustness with fast startup and graceful shutdown. This means that your application should be designed to start up quickly and shut down gracefully.
Again, this is important in cloud-native applications because it allows you to easily scale your application up or down without causing downtime.
10. Dev/prod parity
Keep development, staging, and production as similar as possible. This means that your application should be designed to run in the same way in development, staging, and production environments.
Docker containers are a great way to achieve this because they allow you to package your application and its dependencies in a consistent way.
11. Logs
Treat logs as event streams that can be easily aggregated and analyzed. Ensure that you can run queries on your logs to identify issues and trends.
12. Admin processes
Run admin/management tasks as one-off processes that can be easily run and then shut down.
By following the Twelve-Factor App methodology, developers can create applications that are more reliable, scalable, and maintainable. This methodology provides a set of best practices that cover everything from codebase organization to deployment strategies.