📝 Complaint Management System

A simple Spring Boot REST API for managing Customers and their Complaints.

🚀 Features

• Manage Customers with name & email
• Manage Complaints linked to Customers
• Pagination, Sorting, and Filtering support
• Input validation and error handling
• Kafka & Kafka UI implementation
• Swagger UI for API documentation
• Integration tests with Testcontainers
• Dockerized with PostgreSQL database

🛠️ Technologies

• Java 24+ & Spring Boot 3
• Spring Data JPA & Hibernate
• PostgreSQL (Dockerized)
• Kafka & UI
• Spring Security (basic auth)
• Swagger/OpenAPI UI
• Testcontainers for integration tests
• Docker & Docker Compose
• Elasticsearch – Search and analytics engine for logs.
• Logstash – Collects and processes logs from the application.
• Kibana – Web interface for visualizing logs.

Prerequisites

Before running the application, ensure you have the following installed:

• Java 24 or higher
• Docker (optional, for running the app in a container)
• IntelliJ IDEA (or any Java IDE)
• PostgreSQL (if not using Docker)

Running the Application

1. Running via IntelliJ IDEA

To run the application directly from IntelliJ IDEA:

1. Open the project in IntelliJ IDEA.
2. Navigate to the src/main/java/pl/kkozera/recruitment_task/ directory.
3. Import project as Maven/Gradle project.
4. Ensure PostgreSQL is running locally on port 5432 with these credentials:
   • DB: complains
   • User: appuser
   • Password: apppass
   • you can use this command if using docker:

      docker run -d --name my-postgres -e POSTGRES_USER=appuser -e POSTGRES_PASSWORD=apppass -e POSTGRES_DB=complains -p 5432:5432 postgres:15

5. Ensure Kafka is running locally on port 9092
6. Right-click on the main class (e.g., RecruitmentTaskApplication.java) and select Run.
7. The application should start running on localhost:8080.

2. Running via Docker Compose

You can run the application, kafka with zookeeper, kafka UI and the PostgreSQL database using Docker Compose. This allows you to avoid manually setting up the database.

Steps to run via Docker Compose:

1. Ensure Docker is running on your machine.

2. Ensure the docker-compose.yml and Dockerfile are in the root directory.

3. From the project root, run the following commands:

   ./gradlew clean build

   docker-compose up --build

4. The application and the other dependencies will be spun up in Docker containers. You can access the API at http://localhost:8080.

5. Use /login page to login using these credentials:

   • username: user
   • password: fetch the password from logs of the application

Configuration:

• Database: PostgreSQL will be set up automatically by Docker Compose.
• Ports:
  • Application: 8080
  • PostgreSQL: 5432

3. Swagger UI

Swagger UI is available for API documentation.

• Access Swagger UI at: http://localhost:8080/swagger-ui.html

Here, you can view all the API endpoints and interact with the API directly.

4. 📊 Kafka UI (Kafdrop)

Kafka messages can be viewed through the Kafka web UI:

URL: http://localhost:9000

Use this to inspect topics, messages, consumer groups, etc.

5. 📊 Viewing Logs in Kibana

Open http://localhost:5601

Go to Management → Stack Management → Index Patterns

Create an index pattern (e.g., app-logs-*)

Use Discover to explore logs in real time

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