📰 Blog Microservices Application

A microservices-based Blog Platform built with Spring Boot, following a DB-per-service architecture.
Each microservice manages its own data and communicates via OpenFeign (synchronous REST).
The system includes AI integration, centralized monitoring (Prometheus + Grafana), and containerized PostgreSQL databases.

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🚀 Architecture Overview

This application consists of five independent Spring Boot services:

Service	Description	Port	Database
🧑‍💻 user-service	Manages user profiles and authentication	8081	userdb
📝 post-service	Handles blog post creation, updates, and listing	8082	postdb
💬 comment-service	Manages comments on posts	8083	commentdb
🌐 api-gateway	Spring Cloud Gateway for unified routing	8080	—
🤖 ai-service	Provides AI-driven content analysis and text generation	8084	—

Each service is independently deployable, maintains its own database, and exposes REST APIs for interaction.

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🧩 Key Features

• Microservices Architecture — loosely coupled services, each with its own PostgreSQL DB.
• OpenFeign Integration — inter-service REST communication.
• AI Integration — AI-powered service for generating or summarizing content.
• Spring Boot Actuator + Prometheus + Grafana — real-time metrics and dashboards.
• Centralized Logging — structured logs saved under /log directory.
• Integration Testing — using RestAssured for end-to-end service tests.
• API Gateway — unified entry point for routing and load balancing.

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🗂️ Project Structure

blog-microservices/
│
├── user-service/
│   ├── src/
│   ├── pom.xml
│   └── Dockerfile
│
├── post-service/
│   ├── src/
│   ├── pom.xml
│   └── Dockerfile
│
├── comment-service/
│   ├── src/
│   ├── pom.xml
│   └── Dockerfile
│
├── api-gateway/
│   ├── src/
│   ├── pom.xml
│   └── Dockerfile
│
├── ai-service/
│   ├── src/
│   ├── pom.xml
│   └── Dockerfile
│
├── pom.xml
├── docker-compose.yml
├── prometheus.yml
└── README.md

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⚙️ Technology Stack

Category	Technologies
Backend Framework	Spring Boot 3.x
API Communication	OpenFeign
Database	PostgreSQL (DB-per-service)
Testing	JUnit 5, RestAssured
Monitoring	Prometheus, Grafana
Logging	SLF4J + Logback (output to /log)
Containerization	Docker, Docker Compose
Gateway	Spring Cloud Gateway
AI Integration	Custom AI service (e.g., OpenAI API or local model)

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🐳 Docker Compose Setup

The included docker-compose.yml provisions:

• Three PostgreSQL databases (userdb, postdb, commentdb)
• Prometheus and Grafana monitoring stack

Start the stack

docker-compose up -d

Stop the stack

docker-compose down

Access Points

Service	URL
User DB	localhost:5432
Post DB	localhost:5433
Comment DB	localhost:5434
Prometheus	http://localhost:9090
Grafana	http://localhost:3000

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📊 Monitoring with Prometheus & Grafana

1. Each service exposes metrics via Spring Boot Actuator at:

   http://localhost:<service-port>/actuator/prometheus
   

2. Prometheus scrapes these metrics based on prometheus.yml configuration.
3. Grafana connects to Prometheus as a data source.

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🧠 AI Integration (ai-service)

The AI Service enhances the blogging experience by integrating language model capabilities such as:

• Generating draft post
• Generating a comment for a certain post

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🧪 Integration Testing

Each service includes integration tests under src/test/java using RestAssured:

given()
    .baseUri("http://localhost:8081/users")
.when()
    .get("/1")
.then()
    .statusCode(200)
    .body("username", equalTo("john_doe"));

Run tests via Maven:

mvn test

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📁 Logs

All application logs are stored under:

/log
  ├── user-service.log
  ├── post-service.log
  ├── comment-service.log
  ├── api-gateway.log
  └── ai-service.log

Each service uses Logback with rolling file appenders for production-safe logging.

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🚦 API Gateway Routes

Example routes in api-gateway:

Path	Routed To
/users/**	user-service
/posts/**	post-service
/comments/**	comment-service
/ai/**	ai-service

Example request:

curl http://localhost:8080/posts/1

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🧰 Useful Commands

Action	Command
Build all services	mvn clean package -DskipTests
Build Docker images	docker build -t <service-name> .
Run all services	docker-compose up -d
View logs	docker-compose logs -f
Stop all containers	docker-compose down

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🧑‍💻 Authors

Hejie Zhang
Full-stack developer passionate about distributed systems, observability, and AI-enhanced software design.

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📄 License

This project is licensed under the MIT License — feel free to use and modify with attribution.

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🌟 Future Enhancements

• ✅ Add Kafka for asynchronous event streaming
• ✅ Introduce distributed tracing with Zipkin
• ✅ Deploy to Kubernetes with Helm charts
• ✅ Enable CI/CD with GitHub Actions

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“Monitor everything, test thoroughly, and automate always.”