IT department heads at large enterprises often find themselves in a "legacy system trap." Monolithic architectures, developed decades ago, are becoming too fragile to meet modern security requirements, such as NIS2, and dynamic scaling needs. Fear of operational complexity and unpredictable downtime during full code rewrites often blocks architectural changes, leaving businesses with accumulated technical debt.
Why "big bang" refactoring is a strategic mistake
Attempting a radical replacement of a monolith—the so-called "big bang" refactoring—carries high risks of catastrophic failure. According to Martin Fowler, the monolithic approach is often the most cost-effective in the early stages of system development. However, when a monolith loses its flexibility, attempting to replace it in one step ignores hidden dependencies. This approach almost always leads to incidents where the cost exceeds the benefits of modernization.
Strangler Fig pattern: step-by-step replacement of legacy code
The most viable path for modernization is the "Strangler Fig" pattern. The essence of this method is not immediate removal, but the gradual "overgrowing" of the monolith with new services. This allows for extracting individual business functions, such as reporting or authentication modules, while maintaining access to the current database. Practice shows that even at the first stage, about 13% of functionality can be safely extracted, allowing for testing the new architecture without interrupting business processes.
UnityBase as an architectural foundation
Managed system evolution requires a reliable technological basis. The UnityBase platform, developed by the Intecracy Group alliance, allows for building new services that integrate organically into the existing landscape. UnityBase provides a unified domain metadata model, automated REST API generation, and a security model. This allows new services to operate in parallel with legacy components, utilizing shared RBAC (Role-Based Access Control) and RLS (Row-Level Security) mechanisms to ensure data integrity.
Security as an engineering discipline
Modernization via microservices opens opportunities for implementing the Zero Trust concept, though the architecture itself does not automatically guarantee compliance with NIS2 or ISO/IEC 27001. Using Enterprise or Defence editions of UnityBase for critical infrastructure provides advanced capabilities for auditing, authentication control, and data protection, which require professional configuration. It is important to conduct regular assessments using the AWS Well-Architected Framework to identify security and reliability gaps before critical incidents occur.
Measuring success: DORA metrics in action
To ensure architectural efforts translate into business results, one must rely on objective data. DORA standards (deployment frequency, lead time for changes, change failure rate, and MTTR) allow for performance evaluation. Automating CI/CD pipelines according to 12-Factor App principles (specifically, using stateless processes and environment-based configuration) can lead to a 49% optimization in operational costs, as the team focuses on development rather than manually fixing errors in the monolith.
Checklist for architectural modernization readiness
- Identified a critical business module for the first iteration (isolation from the monolith).
- Implemented 12-Factor App principles (stateless processes, configuration via environment).
- Configured CI/CD for independent deployment of new services.
- Conducted a Well-Architected Review to assess security risks.
- Established baseline DORA metrics to measure delivery speed and stability.
FAQ
How to start monolith modernization without stopping business processes?
Use the Strangler Fig pattern: isolate one business module, deploy it as a microservice, and route traffic through an API gateway, gradually reducing the load on the legacy system.
Is UnityBase a solution for microservice architecture?
UnityBase provides a technical foundation, including domain metadata and automated APIs, which allows for modular system expansion and integration of new services with the existing environment.
How to ensure NIS2 compliance when transitioning to microservices?
Compliance is achieved through end-to-end auditing, row-level security (RLS), and centralized authentication management, which requires rigorous engineering discipline.