Core System Legacy Pitfalls
The client, a leading multinational retail bank, struggled with high maintenance fees, sluggish system responses, and operational failures during high-volume salary processing days. The legacy monolithic mainframe architecture made deploying software updates a high-risk event, often requiring full-system downtime and hours of manual verification.
To remain competitive and lower operations costs, the bank needed to refactor its transaction processing systems into modern, resilient, and auto-scalable infrastructure.
Microservices Decomposition Strategy
We collaborated with the bank's core engineering team to decompose the legacy monolithic application into modular microservices written in Java and Go. Each service (e.g. Ledgers, Transfers, Accounts, and Cards) is containerized using Docker and orchestrated via Amazon Elastic Kubernetes Service (EKS).
Traffic routing is managed by a Service Mesh (Istio), enabling canary deployments and advanced telemetry tracking. The EKS clusters utilize horizontal pod autoscalers to handle sudden spikes in user activity dynamically.
Database Migration & Active Sync
Transitioning core transactional data required maintaining data consistency. We migrated millions of database records to Amazon Aurora PostgreSQL, configuring active-active multi-region replication.
During the migration phase, a double-write execution pattern coupled with Kafka messaging queues synchronized records between the legacy mainframe database and the cloud database in real-time, ensuring zero data loss and a risk-free switchover.
Infrastructure Automation and GitOps
To achieve the client's deployment speed goals, we modeled the entire infrastructure using HashiCorp Terraform. Continuous integration and delivery are automated using ArgoCD, implementing a GitOps methodology.
Engineers can now declare cluster states in Git, triggering automated rollout, validation, and rolling updates. This setup accelerated software releases by 65%, reducing deployment cycles from months to under 15 minutes, while maintaining a 99.99% platform availability guarantee.
