Spring Cloud Microservices Demo

A multi-module Spring Cloud project that demonstrates the core building blocks of a microservice architecture: a service registry, an API gateway and two domain services that talk to each other through the registry.

What this demonstrates

• Service discovery with Netflix Eureka (Spring Cloud Netflix).
• Edge routing with Spring Cloud Gateway.
• Two independently deployable Spring Boot services that register themselves with Eureka.
• Inter-service communication, where user-service calls department-service via a Value Object response template.
• Standard Spring Boot patterns: JPA persistence (H2 in-memory), REST controllers, layered architecture.

Architecture

                     +-------------------------+
   client ---------> |   cloud-gateway         |  (Spring Cloud Gateway, port 9191)
                     +-------------+-----------+
                                   |  routes via Eureka
                +------------------+------------------+
                v                                     v
     +---------------------+                +-----------------------+
     |   user-service      | ----- REST --> |  department-service   |
     |   port 9002         |   inter-svc    |  port 9001            |
     |   (DepartmentUser)  |                |  (Department)         |
     +---------------------+                +-----------------------+
                ^                                     ^
                | registers with                      |
                +---------------+---------------------+
                                v
                  +---------------------------+
                  |  service-registry         |  (Netflix Eureka, port 8761)
                  +---------------------------+

Modules

Module	Port	Role
service-registry	8761	Netflix Eureka server. All services register here.
cloud-gateway	9191	Spring Cloud Gateway. Single entry point routing to the right service via Eureka.
department-service	9001	Spring Boot REST service exposing Department resources, persisted in H2 with JPA.
user-service	9002	Spring Boot REST service exposing DepartmentUser resources. Calls department-service and returns a combined response via ResponseTemplateVO.

Tech stack

• Java + Spring Boot 2.7.x
• Spring Cloud 2021.0.4
• Spring Cloud Gateway
• Netflix Eureka (server and clients)
• Spring Data JPA + H2 (in-memory)
• Maven

Run it on your machine

Prerequisites

• Java 17 or newer (java -version)
• No need to install Maven, the project includes the Maven wrapper in each module

Steps

Open four terminals, one per module, and start them in this order:

git clone https://github.com/Haseeb-Khalil/MicroService.git
cd MicroService

# Terminal 1: Eureka registry
cd service-registry && ./mvnw spring-boot:run

# Terminal 2: Department service (wait until Eureka is up)
cd department-service && ./mvnw spring-boot:run

# Terminal 3: User service
cd user-service && ./mvnw spring-boot:run

# Terminal 4: Gateway
cd cloud-gateway && ./mvnw spring-boot:run

On Windows replace ./mvnw with mvnw.cmd.

Verify it's running

• Eureka dashboard: http://localhost:8761 (you should see USER-SERVICE, DEPARTMENT-SERVICE, API-GATEWAY registered)
• Department service direct: http://localhost:9001/departments/1
• User service direct: http://localhost:9002/users/1
• Through the gateway: http://localhost:9191/departments/1 and http://localhost:9191/users/1

Why I built this

Hands-on practice for the microservice patterns I work with at Capgemini on the HMRC Enterprise Integration Services (EIS) programme: independently deployable Spring Boot services, service discovery and routing, and clean inter-service communication.