You already covered the first six factors that make up the 12-factor application, including "Codebase", "Dependencies", "Configuration", "Backing Services", "Build, Release, Run", and "Processes". In this topic, you will continue your exploration of the 12-factor application principles by looking at the remaining six factors in detail.
Factor 7: Port binding
Port binding means enabling an application to become an independent network service. With it, you can interact via a designated port. In a 12-Factor application, each service should be responsible for managing its port binding. This results in self-contained services that you can independently deploy, scale, and easily integrate into various system environments without any changes to their codebase.
If an application exposes its functionality via a designated network port, it turns into an independent, addressable service that can interact with other services or users. This makes the application highly modular and promotes better separation of concerns.
The 12-factor methodology recommends designing applications to be self-contained. This means that all the dependencies you need to run the application are in the application itself. This includes the web server, application server, or any other components required to run the application. This means that a 12-factor application should not rely on the runtime injection of a web server into the execution environment.
Port binding is an important design principle for building cloud-native applications that can be easily deployed and managed in any environment.
Core ideas:
- Export services via port binding
- Each service should bind to a port and communicate with other services via networking.
- One application can be a Backing Service for another application
Factor 8: Concurrency
The concurrency principle states that the application should be able to scale out via the process model inspired by the Unix process model for running service daemons. This means the application should be able to run multiple instances of itself, each handling a subset of the workload. This makes it easy to scale the application horizontally and ensures that it can take many requests.
The 12-factor methodology recommends designing applications to be concurrency-ready from the start. This allows for better resource utilization and handling of various workloads by assigning each task to a specific process type. This approach makes it easier to scale the application horizontally by adding more instances of the same process. The process model also allows for better fault tolerance because if one process crashes, it does not affect the other processes. This means the application can continue serving requests even if one process fails.
Designing an application to be concurrency-ready is essential for building cloud-native applications that can be easily scaled up and down based on demand.
Core ideas:
- Scale-out via the process model
- Expect the application to be running multiple instances on different cores or servers.
- Design the application to use multiple worker processes with different responsibilities.
Factor 9: Disposability
The disposability principle states that the application should maximize robustness with fast startup and graceful shutdown. This means the application should be able to start up quickly and shut down gracefully in response to environmental changes. It makes the application easy to deploy to different environments. This way, the user can promptly restart the application if a process fails.
Disposability means that you can dispose (get rid) of software components and quickly replace them without disrupting the application's overall architecture and functionality. To achieve disposability, the 12-factor methodology recommends using stateless processes that do not store any application state in memory. Instead, the application state should be stored in external shared resources such as databases or message queues.
The following solutions help improve disposability:
- Automation: automation includes automating the process of creating and disposing of components. For example, you can employ containerization technologies such as Docker and Kubernetes to manage the lifecycle of application instances automatically.
- Quick startup and graceful shutdown: application components should start quickly and perform a clean shutdown when terminated. This ensures minimal disruption to users and other components in the system when instances are replaced.
- Monitoring and alerts: monitoring and alert systems should detect component failures and trigger the automated replacement process. The application can maintain continuous operation and a quality user experience by detecting and resolving issues early.
- Self-healing capabilities: self-healing mechanisms within the application architecture can automatically handle failures by spawning new instances or redirecting user traffic to functional components.
Core ideas:
- Maximize the robustness of applications using fast startup and graceful shutdown
- Encourage quick startup times and instant shutdowns without losing unprocessed work
- This increases application reliability and resilience to any ran related failures
Factor 10: Dev/prod parity
Dev/Prod parity refers to minimizing the differences between the development, staging, and production environments in a software development process. The goal is to build software within a consistent environment throughout its life cycle. This reduces the risk of issues arising from discrepancies in technology, configuration, or processes in separate environments. The closer the environments, the easier it is to detect and solve problems and accelerate development.
Dev/Prod Parity is important to reduce the risk of unexpected issues. By keeping development and production environments as similar as possible, developers can identify and fix bugs earlier in the development process. It improves collaboration between team members. Ensuring everyone works in similar environments makes it easier for team members to streamline processes and troubleshoot issues together. It accelerates the development process. By minimizing environmental discrepancies, developers can code, test, and deploy applications more efficiently, resulting in faster development cycles and more reliable software. It enhances application stability. Ensuring parity between environments helps provide a more predictable and stable application, reducing customer-facing issues and improving overall user experience.
To maintain parity, consistent technology stacks should be used across all stages of the development and deployment process. In addition, it is necessary to ensure that databases or other data sources are consistent across environments. This includes schema or structures and the data required to populate test cases. Implementing Continuous Deployment and monitoring processes will also help maintain parity between the environments. It creates a fast feedback loop so that the developers are aware of any issues that arise during deployment and can resolve them promptly. Containerization simplifies the development and deployment process by encapsulating all code, dependencies, and environment settings within a single container. This enables you to maintain parity between environments more easily. Each container provides a consistent environment you can easily deploy across different stages.
Core ideas:
- Maintain continuity between development, staging, and production environments
- Keep the environment similar to minimize discrepancies when deploying software to production
- Use technologies like containerization and orchestration tools to maintain parity
Factor 11: Logs
The Logs principle insists on treating logs as event streams rather than just files. Logs contain valuable information and insights on an application's behavior, performance, and state. A well-designed log management strategy is crucial for monitoring, diagnosing, and troubleshooting issues that may arise during the lifecycle of an application.
There are several key principles for managing logs in 12-Factor Applications.
The application should not be concerned with where the logs are stored or how they are managed. It should simply generate logs as they occur and emit them as event streams. The task of managing and storing logs is delegated to the environment in which the application is running. For easy analysis and correlation, consolidate and manage logs from different components of an application in a central location. This enables quick identification and resolution of issues and provides a holistic view of the system's state. Effective log management includes using tools and techniques to analyze and visualize log data. This makes it easier to spot trends, identify anomalies and pinpoint issues with the application.
Process logs in real-time to ensure immediate feedback on the application's performance and issues. You can achieve this by log streaming, where logs are continuously and asynchronously sent from the application to the log management system. Store and archive log data for an appropriate amount of time, depending on compliance requirements and the organization's needs. This way, you can analyze historical logs for various purposes, such as auditing or trend analysis.
Core ideas:
- Treat logs as event streams
- Centralize and aggregate logs to an external destination
- Integrate with log management tools to filter, visualize, and analyze log data for better issue detection
Factor 12: Admin processes
The admin processes include the tasks needed to support the application's life cycle but which are not involved in the day-to-day operation of the application. These tasks can include:
- Database migration
- Data processing scripts
- Running diagnostics
- One-time scripts to correct anomalies
The complexity and scope of admin processes may differ, but they require effective management to ensure smooth operation of the application.
It is essential to run each admin process independently and keep them isolated from the standard web and worker processes. This separation ensures that admin processes do not interfere with the regular functioning of the application. It also prevents errors arising from miscommunication between processes. Admin processes must be robust and self-contained. This means that they should not rely upon temporary storage or the environment. Ideally, admin processes should be able to run to completion without errors, even if they are started multiple times.
Maintaining the admin processes in version control, similar to the application code, is important. This provides documentation and aids collaboration between teams. Moreover, it ensures that the admin processes running on your production environment are consistent with the application's codebase. The design of admin processes should ensure their ability to operate within the same environment as the application. This includes access to the database, configuration files, and other dependencies. This consistency guarantees the correct functioning of admin processes about the application and its components.
Admin tasks can have a significant impact on the application and its data. There should be proper access control mechanisms in place. Only authorized users should be allowed to execute admin processes. In addition, it is necessary to log and monitor admin processes similar to those for the web and worker processes. This allows for effective administration, troubleshooting, and auditing of tasks, making it easier to identify and address issues proactively.
Core ideas:
- Run admin/management tasks as one-off processes
- Run administrative tasks (like database migration or scripts) in the same environment as the regular processes
- Admin processes should be version controlled, logged, and monitored, similar to other processes
Conclusion
You discovered the Twelve-Factor Application methodology, which provides a solid guideline for building modern applications that can easily scale, are maintainable, and run on numerous environments.
You learned that Port Binding enables an application to become an independent network service. Concurrency provides for scaling out via the process model inspired by Unix. Disposability requires that an application can startup fast and shut down gracefully. Dev/Prod parity instructs to minimize the differences between the development, staging, and production environments. Treat logs as time-ordered event streams. Run admin tasks, such as database migrations and backups, as one-off processes.