Cloud native benefits greatly from the techniques of extreme programming (XP) first put forward by Kent Beck and Cynthia Andres in Extreme Programming Explained (Addison-Wesley). These are a set of techniques that aim to build quality into code by emphasizing simplicity, communication, and feedback. It is a type of agile software development, which means that it is optimized to be flexible and responsive to change.
Principles include:
Small releases
XP emphasizes the importance of delivering small, usable increments of software frequently, rather than waiting until the end of the project to deliver a large, monolithic product. In cloud native, these increments can correspond to microservices.
Collaborative development
XP emphasizes the importance of collaboration between developers, customers, and other stakeholders.
Test-driven development
XP encourages developers to write automated tests for their code before writing the code itself, to ensure that the code is correct and meets the needs of the users.
Refactoring
XP encourages developers to regularly review and improve their code to keep it simple and maintainable.
XP is a flexible approach that can be adapted to the needs of different projects and organizations. It is designed to be adaptable to change and to encourage frequent communication and feedback between everyone involved in the development process.
Test-driven development in particular is a useful tool for cloud native development, as having the tests in place first means that any changes or refactoring can be made with confidence. Learning Test-Driven Development by Saleem Siddiquif (O’Reilly) is a good practical introduction to this subject.
Building Confidence with Testing
For effective cloud native development, going beyond test-driven development to embrace testing in a broader sense is indispensable. Comprehensive testing procedures lay a foundation of confidence, enabling developers to make changes with the assurance that any newly introduced issues would be promptly identified and addressed. Given the intricate nature of cloud native applications, comprised of numerous interconnected components, it is virtually impossible to sustain a desirable pace of development without a robust testing regime.
Here are some critical testing methodologies for cloud native applications:
Unit testing
Focusing on testing isolated functional units within each microservice. It verifies the correctness of individual functions without considering their interactions with other parts of the system.
Integration testing
Concentrates on testing the interaction between microservices, or between a microservice and external services such as databases or messaging systems. It ensures that all components work harmoniously in conjunction.
Contract testing
This involves the verification of the contract between microservices, which could be event-driven or API-based. Contract testing ensures that all services adhere to the agreed-upon interfaces.
Performance testing
This evaluates the application’s performance under various load conditions, determining the system’s behavior under peak load, identifying bottlenecks, and understanding its scalability potential.
Disaster recovery testing
Critical for validating the application’s ability to recover from failures, disruptions, or catastrophes, ensuring that recovery procedures and contingency plans are effective.
Security testing
Ensures the application’s resilience against threats such as hacking or data breaches. It verifies the robustness of the system’s security measures, aiming to safeguard both the system and user data.
User acceptance testing
This is conducted from the perspective of the end user to ensure the application aligns with user expectations and requirements, affirming that it’s ready for deployment.
While testing is a cornerstone of software development regardless of the paradigm, cloud native applications, with their microservices architecture and specific scalability and resilience attributes, demand a nuanced approach. The loose coupling of components, which communicate through APIs or respond to events, calls for an increased emphasis on contract testing to secure the reliability of these interactions. Throughout this book, I will delve into these methodologies and demonstrate how they fortify cloud native development.