01 / Project case study
PrecisionStore
A production-ready distributed e-commerce platform with 6 Spring Boot microservices, service discovery, API Gateway, and a React 19 frontend.
Spring Boot 4 / Java 21 / Spring Cloud 2025 / API Gateway / Eureka / JWT / PostgreSQL / Docker / React 19 / GitHub Actions
Overview
The problem.
An e-commerce application has several different responsibilities. Keeping everything tightly coupled makes it harder to reason about service boundaries, security, and growth. Monolithic architectures become bottlenecks as features scale.
The approach.
A microservices-based architecture with 6 independently deployable Spring Boot services, API Gateway for routing and auth, Eureka service discovery, centralized config, and per-service PostgreSQL databases—all containerized with Docker and orchestrated via CI/CD.
What the project focuses on.
- JWT authentication with access/refresh token rotation
- Role-based authorization (admin vs customer)
- API Gateway routing and header propagation
- Eureka Service Discovery
- Centralized Git-backed configuration
- 6 microservices: User, Product, Cart, Order, Config, Eureka
- Resilience4j circuit breakers with fallbacks
- 4 isolated PostgreSQL databases (database-per-service)
- Docker multi-stage builds and Compose orchestration
- GitHub Actions CI/CD with change-detection
- React 19 frontend with protected routes
Architecture
Select a component to understand its role. On smaller screens, scroll the diagram horizontally.
Architecture overview. Solid lines show application communication; dashed lines show discovery. Eureka is a registry, not an intermediate request server. Data boundaries illustrate a database-per-service pattern.
API Gateway
Spring Cloud Gateway (WebFlux) serves as the single entry point. Routes requests to services, validates JWT tokens, enforces RBAC, and propagates user context via headers (X-User-Id, X-User-Role).
Engineering notes
A problem worth understanding.
- Challenge
- Ensuring stock consistency across services during order placement.
- Cause
- Cart Service and Product Service maintain separate databases; stock validation requires cross-service communication with potential network failures.
- Solution
- Used Feign clients with Resilience4j circuit breakers and fallback implementations, with atomic transaction boundaries in Order Service for stock deduction and cart clearing.
- Result
- Reliable order processing with fault-tolerant stock validation and automatic rollback on failures.
Lessons learned.
- Distributed systems need explicit service boundaries and reliable communication patterns.
- Service discovery connects logical service names to running instances in dynamic environments.
- Authentication and authorization have distinct responsibilities in a secure architecture.
- Docker networking and service registration must agree on how services can reach each other.
- Resilience patterns (circuit breakers, fallbacks) are essential for inter-service communication.
- Database-per-service enables true service autonomy but requires careful transaction design.
- CI/CD with change-detection orchestration enables efficient multi-service deployments.