[DL.EAC.4] Implement continuous configuration for enhanced application management

Category: RECOMMENDED

Configuration as code is the practice of managing and tracking configuration changes as code, providing an audit trail and reducing errors from manual changes. Continuous configuration uses configuration as code to enhance configuration management by allowing configuration changes to be made independently of application code deployments.

Configuration should be separated from application code to allow for independent tracking and management. Use tools designed for managing configurations as code, such as AWS AppConfig, to manage configuration externally from the application. Create fully automated pipelines that perform continuous integration and continuous delivery (CI/CD) based on changes to the configuration code. Just like with application deployment pipelines, these configuration deployment pipelines should run quality assurance tests, followed by deployment in a non-production environment before deploying to production.

It's important to distinguish between static and dynamic configuration types. Static configurations do not change during the software's runtime and are specific to each environment. Dynamic configurations can be adjusted at runtime without downtime. Feature flags are examples of dynamic configurations that can be used to control which features are enabled per environment to decouple release from deployment. Operational configurations, such as log level, throttling thresholds, connection/request limits, alerts, and notifications, can be static or dynamic depending on the use case and need to be managed. Application modes, which toggle the application to run as either development, test, or production, are typically considered to be static configuration that is set at startup and do not change.

General use cases for continuous configuration include application integration tuning, feature toggling, allowing access to premium content through allow lists, and addressing operational issues and troubleshooting. To manage your configurations effectively, establish a routine to prevent configuration bloat. While it can seem tempting to externalize as many variables as possible, an excessively complex configuration file can lead to confusion and errors. Carefully evaluate the necessity, frequency of change, and runtime requirements of each value to decide if it should be included as dynamic configuration. 

For large-scale deployment of configuration as code, a Dynamic Configuration Pipeline is recommended. This allows centralized management of the entire workload configuration and its components across all environments. It ensures that all configurations are version-controlled, adhere to quality assurance and code review processes, and is capable of progressively deploying configuration changes and performing rollbacks as necessary to minimize system disruptions.

Continuous configuration is beneficial in DevOps environments, as it improves operational efficiency and scalability. However, not every system requires the complexity associated with continuous configuration. Therefore, each workload should be evaluated depending on architecture choice, team preferences, and service level objective requirements.

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