🛒 Ecommerce Microservices Project

A polyglot, containerized microservices architecture for an e-commerce platform, built with Spring Boot, Kafka, PostgreSQL, MongoDB, Keycloak for authentication, Eureka for service discovery, and observability via Zipkin, Prometheus, and Grafana.

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🗺️ Architecture Overview

This project uses a microservice architecture with the following components:

• An API Gateway (Spring Cloud Gateway) as the single entrypoint.
• Multiple domain microservices (Product, Order, Inventory, Notification) communicating via HTTP and Kafka.
• Service Discovery with Eureka.
• Centralized authentication using Keycloak (OAuth2 / OIDC).
• Messaging with Kafka (broker + Zookeeper).
• Persistence with PostgreSQL and MongoDB.
• Tracing using Zipkin.
• Monitoring with Prometheus and Grafana.
• Fully containerized and orchestrated via Docker Compose.

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✅ Features

• Microservice architecture with Spring Boot 3.x and Spring Cloud 2023.x
• Service discovery with Eureka
• API Gateway with Spring Cloud Gateway
• Synchronous and asynchronous communication (HTTP, Kafka)
• Kafka for event-driven messaging
• Resilience4j circuit breaking, retry, timeouts
• Distributed tracing with Zipkin
• Metrics monitoring with Prometheus and Grafana
• OAuth2 / OIDC authentication with Keycloak
• SQL (PostgreSQL) and NoSQL (MongoDB) databases
• Docker Compose orchestration

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🧩 Services

Service	Description	Tech Stack
API Gateway	Single entrypoint with routing	Spring Cloud Gateway
Product Service	Product catalog CRUD	Spring Boot, MongoDB
Order Service	Order placement, transactional boundaries	Spring Boot, PostgreSQL
Inventory Service	Stock management	Spring Boot, PostgreSQL
Notification Service	Kafka consumer for order events	Spring Boot, Kafka
Discovery Server	Service registry	Eureka
Auth Server	User login, OAuth2, OIDC	Keycloak, MySQL
Messaging	Asynchronous events	Kafka, Zookeeper
Tracing	Distributed tracing	Zipkin
Monitoring	Metrics and visualization	Prometheus, Grafana

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⚙️ Prerequisites

• Docker & Docker Compose
• Java 17+
• Maven

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🚀 Getting Started

Clone the repo:

git clone https://github.com/rahijamil/springboot-ecommerce-microservices.git
cd springboot-ecommerce-microservices

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🐳 Running with Docker Compose

1️⃣ Build all services

Make sure you’ve built your Spring Boot microservice JARs into Docker images (they're tagged in the Compose file as rahijamil/{service}:latest):

# Example for all modules
mvn clean package -DskipTests

docker build -t rahijamil/product-service ./product-service
docker build -t rahijamil/order-service ./order-service
docker build -t rahijamil/inventory-service ./inventory-service
docker build -t rahijamil/notification-service ./notification-service
docker build -t rahijamil/api-gateway ./api-gateway
docker build -t rahijamil/discovery-server ./discovery-server

2️⃣ Start the full stack

docker-compose up --build

This will launch:

• Databases (Postgres, Mongo, MySQL for Keycloak)
• Zookeeper, Kafka broker
• Zipkin
• Eureka Server
• API Gateway
• All microservices
• Prometheus & Grafana

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⚡ Ports & Endpoints

Service	Port (Host)	Notes
API Gateway	8181	Entry point for frontend
Discovery Server	8761	Eureka dashboard
Keycloak	8080	Auth server admin UI
Kafka Broker	9092/29092	External / internal listeners
Zookeeper	2181	Kafka dependency
Zipkin	9411	Tracing dashboard
Prometheus	9090	Metrics dashboard
Grafana	3000	Visualization dashboard
MongoDB	27017	Product DB
Postgres (Order)	5431	Order DB
Postgres (Inventory)	5432	Inventory DB
Keycloak MySQL	3306	Auth DB

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🔑 Authentication

• Auth server (Keycloak) runs at http://localhost:8080

• Default Admin Credentials:

  • Username: admin
  • Password: admin

• Uses imported realm from ./realms/

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🛠️ Prometheus Monitoring

Prometheus is configured to scrape /actuator/prometheus endpoints of:

• Product Service
• Order Service
• Inventory Service
• Notification Service

Example scrape config:

scrape_configs:
  - job_name: 'order_service'
    metrics_path: '/actuator/prometheus'
    static_configs:
      - targets: ['order-service:8080']

Important: Each service must include:

management.endpoints.web.exposure.include=prometheus

And have dependency:

<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-registry-prometheus</artifactId>
</dependency>

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📈 Observability Dashboards

• Zipkin: http://localhost:9411

• Prometheus: http://localhost:9090

• Grafana: http://localhost:3000

  • Default login:

    • User: admin
    • Password: password

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💬 Example cURL

Example to place an order via the API Gateway:

curl -X POST http://localhost:8181/api/order/place \
  -H "Content-Type: application/json" \
  -d '{
    "orderLineItemsDtoList": [
        {
            "skuCode": "iphone_17",
            "price": 1200,
            "quantity": 1
        }
    ]
}'

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✅ Notes & Troubleshooting

• Services must register with Eureka before API Gateway can route.
• Ensure Kafka Broker and Zookeeper are running before producers/consumers.
• If Prometheus target shows DOWN with 404, ensure /actuator/prometheus is exposed.
• If Keycloak fails to start, verify MySQL connectivity and volume paths.

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🙏 Acknowledgements

• Spring Boot
• Spring Cloud
• Apache Kafka
• PostgreSQL & MongoDB
• Keycloak
• Zipkin
• Prometheus & Grafana