Twelve-Factor Methodology for Cloud-Native Application Design
Codebase: One Codebase, Many Deployments The first factor emphasizes that an application should have a single codebase tracked in version control, with multiple deploys. This means that the source code for the application is stored in one repository and can be deployed to various environments, such as development, staging, and production. This approach ensures consistency and simplifies version control, making it easier to track changes and manage different versions of the application.
Dependencies: Explicitly Declare and Isolate Dependencies Applications should explicitly declare their dependencies, including libraries and tools, in a manifest file. This allows the application to be self-contained and ensures that all necessary dependencies are included in the deployment. By isolating dependencies, applications avoid conflicts and reduce the risk of errors caused by missing or incompatible libraries.
Config: Store Configuration in the Environment Configuration settings, such as database credentials and API keys, should be stored in environment variables rather than in the codebase. This separation of configuration from code allows for different configurations to be used in different environments without modifying the application code. It also enhances security by keeping sensitive information out of the codebase.
Backing Services: Treat Backing Services as Attached Resources Backing services, such as databases, message queues, and caches, should be treated as external resources that are attached to the application. This means that the application interacts with these services through well-defined interfaces and does not rely on their internal implementation. This approach allows for greater flexibility in swapping out or scaling backing services without affecting the application.
Build, Release, Run: Strictly Separate Build and Run Stages The build, release, and run stages of an application should be strictly separated. The build stage involves compiling the source code and creating artifacts, the release stage involves deploying these artifacts to an environment, and the run stage involves executing the application. This separation ensures that each stage is independent and can be managed separately, allowing for more controlled and predictable deployments.
Processes: Execute the App as One or More Stateless Processes Applications should be designed to run as stateless processes that can be easily scaled and replicated. Stateless processes do not rely on local storage and can handle requests independently. This design simplifies scaling and makes it easier to manage and deploy the application in a distributed environment.
Port Binding: Export Services via Port Binding Applications should export their services by binding to a specific port and listening for incoming requests. This approach allows applications to be accessed over a network and makes it easier to integrate with other services. By using port binding, applications can be easily exposed to the outside world and interact with other components in the system.
Concurrency: Scale Out via the Process Model Applications should be designed to scale out by running multiple processes that handle different tasks concurrently. This approach allows the application to handle increased load by adding more processes rather than relying on a single, monolithic process. Scaling out improves performance and ensures that the application can handle high levels of traffic and workload.
Disposability: Maximize Robustness with Fast Startup and Shutdown Applications should be designed to start up quickly and shut down gracefully. Fast startup times allow for rapid deployment and scaling, while graceful shutdown ensures that ongoing tasks are completed and resources are properly released. This design approach enhances the robustness of the application and improves its ability to handle failures and restarts.
Dev/Prod Parity: Keep Development, Staging, and Production as Similar as Possible Development, staging, and production environments should be as similar as possible to reduce the risk of discrepancies and bugs. By keeping these environments consistent, developers can ensure that the application behaves the same way in all stages of deployment. This approach minimizes the risk of environment-specific issues and simplifies the debugging and testing process.
Logs: Treat Logs as Event Streams Logs should be treated as streams of events that are emitted by the application and can be aggregated and analyzed. Applications should not manage log storage or processing; instead, logs should be forwarded to a centralized logging service for analysis and monitoring. This approach allows for better visibility into the application's behavior and facilitates troubleshooting and performance monitoring.
Admin Processes: Run Administrative/Management Tasks as One-Off Processes Administrative and management tasks, such as database migrations and backups, should be run as one-off processes that are separate from the main application processes. This design ensures that administrative tasks do not interfere with the normal operation of the application and allows for greater flexibility in managing and maintaining the application.
Conclusion The twelve-factor methodology provides a comprehensive set of guidelines for designing and managing cloud-native applications. By following these principles, developers can build applications that are scalable, maintainable, and robust, making it easier to deploy and manage applications in modern cloud environments. Implementing these practices helps ensure that applications are well-suited to the demands of cloud computing and can adapt to changing requirements and environments.
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