Citation :

Daniel Thomas , 2026. "Modernizing Legacy Systems through Scalable Microservices and DevOps Practices" ESP International Journal of Advancements in Science & Technology (ESP-IJAST)  Volume 4, Issue 2: 67-80.

Abstract :

A legacy monolithic application was successfully refactored into a containerized microservices architecture, uti- lizing modern DevOps practices to enhance scalability, main- tainability, and security. The original system, built with Flask, Python2, and SQLite, was re-engineered with an ASP.NET Core backend, a ReactJS frontend, and a PostgreSQL database, follow- ing Clean Architecture and SOLID principles. This architecture was deployed on a managed Kubernetes cluster, enabling hori- zontal scaling and fault tolerance. Key features such as automated SSL encryption, secrets management, and Prometheus-based monitoring were integrated to improve security and observability. The refactor not only supports efficient continuous delivery and infrastructure automation but also leverages microservices for independent scaling, technology diversity, and rapid feature de- ployment, demonstrating the powerful synergy between modern application design and DevOps principles.

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Keywords :

Microservices Architecture, DevOps, Kubernetes, CI/CD Pipeline, Containerization, Clean Architecture, ASP.NET Core, ReactJS, PostgreSQL, Application Modernization.