Microservices With Spring Boot And Spring Cloud

That is repository with examples used for video course Microservices With Spring Boot And Spring Cloud.

Requirements

To run the example applications you need to have installed:

1. Intellij IDEA
2. JDK 11+
3. Maven

Structure

Each directory in the root project is related with the single part of the course.

Part 1 - Introduction to Spring Boot

• intro-to-spring-boot

Part 2 - Distributed configuration & service discovery

• config-and-discovery

Part 3 - Inter-service communication

• inter-communication

Part 4 - API Gateway

• api-gateway

Part 5 - Event-driven microservices

• event-driven

Overview

This repository showcases a set of Spring Cloud sample applications that demonstrate core patterns and best practices for building microservices with Spring Boot, Spring Cloud Gateway, Eureka Discovery, Config Server, OpenFeign, and Kafka/Spring Cloud Stream. Each module provides hands-on examples for common cloud-native scenarios, enabling developers to explore and adapt these patterns in their own projects.

Prerequisites

• JDK 17+
• Maven 3.9+
• Docker & Docker Compose (optional)

Module Architecture

Module	Services	Ports
intro-to-spring-boot	simple-service	8080
inter-communication	sender-service, receiver-service	8080
event-driven	producer-service, consumer-a-service, consumer-b-service	8080
api-gateway	gateway-service	8080
config-and-discovery	config-server (8080), discovery-server (8761)	8080, 8761

intro-to-spring-boot

• Purpose: A minimal Spring Boot application demonstrating a simple RESTful endpoint.
• Tech stack: Spring Boot, Spring Web.
• Services:

Service	Port	Description
simple-service	8080	Returns a greeting message via REST API.

sequenceDiagram
    participant Client
    participant simple-service
    Client->>simple-service: GET /greet
    simple-service-->>Client: 200 OK, "Hello, World!"

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inter-communication

• Purpose: Illustrates synchronous service-to-service calls using OpenFeign.
• Tech stack: Spring Boot, Spring Web, Spring Cloud OpenFeign.
• Services:

Service	Port	Description
sender-service	8080	Calls receiver-service using a Feign client.
receiver-service	8080	Exposes an endpoint that returns sample data.

sequenceDiagram
    participant Sender
    participant Receiver
    Sender->>Receiver: GET /api/data
    Receiver-->>Sender: 200 OK, { "value": "sample" }

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event-driven

• Purpose: Demonstrates asynchronous messaging with Kafka and Spring Cloud Stream.
• Tech stack: Spring Boot, Spring Cloud Stream, Kafka Binder.
• Services:

Service	Port	Description
producer-service	8080	Publishes events to a Kafka topic.
consumer-a-service	8080	Listens to topic and processes messages.
consumer-b-service	8080	Listens to topic and processes messages.

sequenceDiagram
    participant Producer
    participant Kafka
    participant ConsumerA
    participant ConsumerB
    Producer->>Kafka: publish OrderCreated
    Kafka-->>ConsumerA: OrderCreated
    Kafka-->>ConsumerB: OrderCreated

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api-gateway

• Purpose: Serves as the edge router for all incoming requests.
• Tech stack: Spring Boot, Spring Cloud Gateway.
• Services:

Service	Port	Description
gateway-service	8080	Routes requests to downstream microservices.

config-and-discovery

• Purpose: Centralized configuration and service registration/discovery.
• Tech stack: Spring Boot, Spring Cloud Config, Spring Cloud Netflix Eureka.
• Services:

Service	Port	Description
config-server	8080	Serves configuration properties to client applications.
discovery-server	8761	Registers and discovers microservices via Eureka Dashboard.

Running the Examples

1. Start Config Server:
   mvn -pl config-and-discovery/config-server spring-boot:run
2. Start Discovery Server (Eureka) on port 8761:
   mvn -pl config-and-discovery/discovery-server spring-boot:run
3. Start API Gateway:
   mvn -pl api-gateway/gateway-service spring-boot:run
4. Start each remaining service (choose order as needed):
   mvn -pl / spring-boot:run

Alternative (Docker Compose):

docker-compose -f docker-compose.yml up

(Note: docker-compose.yml not included by default; add one if desired.)

Testing the Services

• simple-service:

  curl http://localhost:8080/greet

• sender-service → receiver-service:

  curl http://localhost:8080/send?msg=hello

• producer-service → consumers:

  curl -X POST http://localhost:8080/orders -H "Content-Type: application/json" -d '{"id":123}'

• API Gateway routing:

  curl http://localhost:8080/api/simple/greet

Contributing

Contributions are welcome! Please submit pull requests with clear descriptions of changes. Each module is organized to demonstrate specific Spring Cloud components (Web, Feign, Kafka Binder, Config, Eureka, Gateway). Ensure that code adheres to existing style and patterns.

License

This project is licensed under the MIT License. See the LICENSE file for details.