The Twelve-Factor App methodology is a set of best practices designed to enable applications to be built with portability and resilience when deployed on the web. It was first proposed by engineers at Heroku, a cloud-based platform as a service (PaaS) provider, and has since been adopted by many organizations developing software-as-a-service apps.
These principles are designed to enable applications to be built with portability, resilience, and scalability, making them ideally suited for deployment in the cloud. This methodology provides a high degree of automation, minimizing the time and cost of setup, scaling, and management of applications.
Definition of Twelve-Factor App
The Twelve-Factor App methodology is a manifesto that outlines twelve best practices for building modern, scalable, maintainable software-as-a-service apps. These twelve factors can be broadly categorized into three areas: codebase, dependencies, and configurations.
The methodology emphasizes the use of declarative formats, clean contract with the underlying operating system, treating backing services as attached resources, strict separation of build, release, and run stages, processes, port binding, concurrency, disposability, dev/prod parity, logs, and admin processes.
Codebase
The first factor in the Twelve-Factor App methodology is having one codebase tracked in revision control with many deploys. This means that there should be exactly one codebase for a deployed service with the codebase being used for many deployments.
This approach enables developers to make changes to the codebase at any time, yet it allows any version of the code to be built and deployed. It also allows every developer to have a local copy of the entire codebase, enabling them to work independently and submit changes through the version control system.
Dependencies
The second factor involves explicitly declaring and isolating dependencies. This means that a Twelve-Factor App should never rely on the implicit existence of system-wide packages. Instead, it declares all dependencies, completely and exactly, via a dependency declaration manifest.
This approach ensures that no implicit dependencies "leak in" from the surrounding system. The app's isolation from its environment ensures that it is portable and can be deployed consistently in any environment.
Explanation of Twelve-Factor App
The Twelve-Factor App methodology is a conceptual framework for building software that promotes best practices in modern application development. It is particularly relevant in the context of cloud computing, where applications need to be scalable, portable, and resilient.
Each of the twelve factors represents a segment of recommendations and represents a standard that should be met in order to ensure optimal application performance. While these factors can be applied to software development in general, they are particularly well-suited to cloud-native and serverless architectures.
Configurations
The third factor involves storing configurations in the environment. This means that an app's configuration, everything that is likely to vary between deploys, should be stored in the environment, not in the app itself.
This approach enables the app to be a true "twelve-factor" app, and it can be open-sourced at any time, without compromising any credentials.
Backing Services
The fourth factor involves treating backing services as attached resources. This means that a Twelve-Factor App makes no distinction between local and third-party services. To the app, both are attached resources, accessed via a URL or other locator/credentials stored in the configuration.
This approach enables the app to be easily moved between different environments, as the resources it needs can be attached and detached at will.
History of Twelve-Factor App
The Twelve-Factor App methodology was first proposed by Adam Wiggins, the co-founder of Heroku, in 2011. The methodology was developed in response to the growth of cloud computing and the need for a set of best practices for developing applications that could leverage the advantages of the cloud.
The methodology has since been widely adopted by many organizations and has influenced the design of many cloud-native applications. It has also influenced the development of microservices architecture, which shares many of the same principles.
Impact on Software Development
The Twelve-Factor App methodology has had a significant impact on how modern software is developed. Its emphasis on factors such as codebase, dependencies, and configurations has led to more modular, scalable, and maintainable applications.
By following these principles, developers can build applications that are optimized for the cloud, making them more resilient and scalable. This has made the methodology particularly popular among organizations building software-as-a-service (SaaS) applications.
Adoption by Major Tech Companies
Many major tech companies have adopted the Twelve-Factor App methodology for developing their applications. Companies like Netflix, Amazon, and Google have all used the methodology to some extent, particularly in their cloud services.
The methodology's principles align well with these companies' focus on providing highly scalable, reliable services. By following the Twelve-Factor App methodology, these companies can ensure that their applications are designed to take full advantage of the cloud.
Use Cases of Twelve-Factor App
The Twelve-Factor App methodology can be used in a variety of scenarios, but it is particularly well-suited to cloud-native applications. These are applications that are designed from the ground up to run in the cloud, taking full advantage of the cloud's scalability and resilience.
The methodology is also well-suited to microservices architectures, where applications are broken down into smaller, independent services that can be developed, deployed, and scaled independently. By following the Twelve-Factor App methodology, developers can ensure that each microservice is well-designed and can operate effectively in the cloud.
Software-as-a-Service (SaaS) Applications
Software-as-a-Service (SaaS) applications are a common use case for the Twelve-Factor App methodology. These are applications that are delivered over the internet, typically on a subscription basis.
By following the Twelve-Factor App methodology, developers can ensure that their SaaS applications are scalable, resilient, and easy to maintain. This can lead to improved user experience, lower costs, and increased revenue.
Microservices Architectures
Microservices architectures are another common use case for the Twelve-Factor App methodology. In a microservices architecture, an application is broken down into smaller, independent services that can be developed, deployed, and scaled independently.
By following the Twelve-Factor App methodology, developers can ensure that each microservice is well-designed and can operate effectively in the cloud. This can lead to more scalable, resilient applications that are easier to maintain and update.
Examples of Twelve-Factor App
There are many examples of applications that have been built using the Twelve-Factor App methodology. These range from small, independent projects to large-scale applications developed by major tech companies.
In all cases, the Twelve-Factor App methodology has been used to guide the design and development of the application, ensuring that it is scalable, resilient, and easy to maintain.
Heroku
Heroku, the company that first proposed the Twelve-Factor App methodology, is a prime example of its application. Heroku's platform as a service (PaaS) allows developers to build, run, and operate applications entirely in the cloud.
By following the Twelve-Factor App methodology, Heroku ensures that all applications deployed on its platform are designed to take full advantage of the cloud's scalability and resilience.
Netflix
Netflix, the world's leading streaming entertainment service, is another example of a company that uses the Twelve-Factor App methodology. Netflix's streaming service is built on a microservices architecture, with each microservice following the principles of the Twelve-Factor App methodology.
This approach has allowed Netflix to build a highly scalable, resilient service that can handle the demands of over 200 million subscribers worldwide.
Conclusion
The Twelve-Factor App methodology is a set of best practices for developing modern, scalable, maintainable software-as-a-service apps. By following these principles, developers can build applications that are optimized for the cloud, making them more resilient, scalable, and easy to maintain.
Whether you're a developer looking to build a new application or an organization looking to modernize your existing applications, the Twelve-Factor App methodology provides a proven framework for success.