ePasal Backend (Spring Boot Microservices)

This repo contains the backend for an e-commerce app built with Spring Boot using a microservice architecture.

Services

• API Gateway (APICloudGateway) — Spring Cloud Gateway (WebFlux) + OAuth2 resource server
• Service Discovery (eurekaServer) — Netflix Eureka
• User/Auth (UserService) — auth, user management, OTP/code flows
• Product (ProductService) — product catalog (MongoDB) + Cloudinary integration
• Cart (CartService) — cart management
• Order (OrderService) — orders + payment integrations
• Inventory (InventoryService) — inventory management
• Mail (MailServer) — email sending + RabbitMQ listeners + Thymeleaf templates

Tech Stack (from the Maven poms)

• Java 21
• Spring Boot 4.0.5
• Spring Cloud 2025.1.0
• Eureka (service discovery) + Spring Cloud LoadBalancer
• Spring Cloud Gateway (WebFlux)
• Security: Spring Security + OAuth2 Resource Server
• Inter-service calls: OpenFeign
• Resilience: Resilience4j circuit breaker (dependency included in Cart/Product/Order)
• Datastores:
  • MySQL (JPA/Hibernate) — User/Cart/Order/Inventory
  • MongoDB — Product
  • Redis — used in UserService (rate limiting / attempt tracking)
• Messaging: RabbitMQ (Spring AMQP)
• OpenAPI/Swagger: springdoc-openapi (each service) + aggregated Swagger UI at the gateway
• Email: Spring Mail + Thymeleaf templates (MailServer)
• Mapping: MapStruct (DTO mapping)

Spring Boot Topics Covered

• Microservices with service discovery (Eureka) and gateway routing
• JWT/OAuth2 resource server setup (service-side)
• Database per service pattern (MySQL + MongoDB)
• Async/event-driven communication with RabbitMQ
• Centralized API docs via SpringDoc + gateway aggregation
• Validation (spring-boot-starter-validation)
• Resilience patterns (circuit breaker via Resilience4j)
• DTO mapping (MapStruct)

Backend Engineering Principles Implemented

• API Gateway: single entry point + route rewriting to internal services
• Service discovery + client-side load balancing: services register to Eureka and are called via lb://...
• Event-driven email: User/Order events published to RabbitMQ and consumed by MailServer
• Rate limiting & abuse protection (UserService): request cooldown + attempt window enforced using Redis
• Password reset flow: password reset codes emitted as events and emailed via MailServer templates
• Separation of concerns: separate services + separate databases where applicable
• Fault tolerance: circuit breaker around downstream calls (where configured)

API Docs (Swagger)

• Public Swagger UI: https://backend.poudelsunil.info.np/swagger-ui/index.html

When running locally via Docker, the gateway Swagger UI should be at:

• http://localhost:8080/swagger-ui/index.html

Running Locally (Docker Compose)

Prereqs:

• Docker + Docker Compose + maven

From the repo root:

mvn clean package -DskipTests
docker compose up --build

This starts:

• Gateway: 8080
• UserService: 8081
• ProductService: 8082
• CartService: 8083
• OrderService: 8084
• InventoryService: 8085
• MailServer: 8086
• Eureka: 8761
• MySQL: 3306
• RabbitMQ: 5672 (AMQP), 15672 (management UI)
• Redis: 6379

Cloud Deployment (AWS EC2 + Docker)

This backend is deployed on an AWS EC2 instance using Docker containerization (the same services you run locally are packaged as containers and orchestrated with Docker Compose on the server).

High-level deployment approach:

• Build/publish service images (or build on the instance)
• Copy/update the Compose config on the EC2 host
• Run the stack with docker compose up -d (and docker compose pull when using a registry)

Operational notes:

• Typically only the API Gateway is exposed publicly; the other services stay on the Docker network.
• Ensure the EC2 security group only allows required inbound ports (commonly 80/443 for HTTP/HTTPS, plus SSH for administration).
• Public Swagger UI (via gateway): https://backend.poudelsunil.info.np/swagger-ui/index.html

Notes / Config

• OAuth2 (Google): UserService has Google OAuth client config in application.yml. For local auth flows you’ll need to use your own client id/secret and correct redirect URI.
• JWT keys: services validate JWT using classpath:keys/public.key. UserService also has the private key for signing.
• MongoDB: ProductService expects a MongoDB URI (currently set in application.yml).
• SMTP: MailServer is configured for Gmail SMTP in application.yml.

Repo Layout

• microservice/ contains one Spring Boot project per service.
• Root compose.yaml runs the full stack for local development.