CafeOJ - Online Judge Platform

A Spring Boot-based online judge platform for problem solving.

🚀 Quick Start with Docker

Prerequisites

• Docker (20.10+)
• Docker Compose (2.0+)

Setup Environment Variables

Before starting, create your environment file:

# Copy the example environment file
cp .env.example .env

# Edit .env with your preferred values (optional for development)
nano .env

The .env file contains sensitive configuration:

# Database credentials
POSTGRES_DB=cafeoj
POSTGRES_USER=cafeoj_user
POSTGRES_PASSWORD=your_secure_password

# Admin account password (created on first startup)
ADMIN_PASSWORD=your_admin_password

⚠️ Important: Never commit .env to version control. It's already in .gitignore.

Run Using Docker Compose

# Start the application
docker compose up --build -d

# View logs
docker compose logs -f

# Stop the application
docker compose down

📦 What Gets Created

When you run the Docker setup, the following components are created:

1. PostgreSQL Container (cafeoj-postgres)

   • Database: configured via POSTGRES_DB
   • User: configured via POSTGRES_USER
   • Password: configured via POSTGRES_PASSWORD
   • Port: 5432

2. Spring Boot Application Container (cafeoj-app)

   • Port: 8080
   • Profile: docker
   • Admin user created with password from ADMIN_PASSWORD

3. Persistent Volume (postgres-data)

   • Stores all database data
   • Survives container restarts

4. Network (cafeoj-network)

   • Allows containers to communicate

🌐 Access the Application

Once started, access the application at:

• Homepage: http://localhost:8080

📋 Available Commands

Docker Compose Commands

docker compose up -d              # Start in detached mode
docker compose up --build -d      # Build and start
docker compose down               # Stop services
docker compose down -v            # Stop and remove volumes
docker compose logs -f            # Follow logs
docker compose logs -f app        # Follow app logs only
docker compose ps                 # Show status
docker compose restart            # Restart services

🛠️ Development Workflow

Making Code Changes

1. Edit your code in the src directory
2. Rebuild and restart:

    docker compose up --build -d

Database Access

To access the PostgreSQL database directly:

docker exec -it cafeoj-postgres psql -U cafeoj_user -d cafeoj

Common PostgreSQL commands:

\dt              -- List tables
\d users         -- Describe users table
SELECT * FROM users;  -- Query users
\q               -- Quit

🔧 Configuration

Environment Variables

All sensitive configuration is managed via the .env file. Available variables:

Variable	Description	Default
POSTGRES_DB	Database name	cafeoj
POSTGRES_USER	Database username	cafeoj_user
POSTGRES_PASSWORD	Database password	(required)
ADMIN_PASSWORD	Admin account password	admin

To customize:

# Create .env from template
cp .env.example .env

# Edit with your values
nano .env

Port Conflicts

If ports 8080 or 5432 are already in use, edit docker compose.yml:

services:
  app:
    ports:
      - "8081:8080" # Change external port
  postgres:
    ports:
      - "5433:5432" # Change external port

📁 Project Structure

CafeOJ/
├── docker compose.yml          # Docker Compose configuration
├── Dockerfile                  # Application container definition
├── .dockerignore              # Files to exclude from Docker build
├── .env.example               # Environment variables template
├── README-DOCKER.md           # Detailed Docker documentation
├── src/
│   └── main/
│       ├── java/              # Java source code
│       └── resources/
│           ├── application.properties        # Default config
│           └── application-docker.properties # Docker config
└── pom.xml                    # Maven configuration

🔒 Security Notes

For production deployment:

1. Change default passwords in your .env file (never use defaults in production)
2. Keep .env secret - it's gitignored and should never be committed
3. Use secrets management (Docker secrets, Kubernetes secrets, etc.) for production
4. Enable HTTPS with proper SSL certificates
5. Configure firewall rules
6. Set up monitoring and alerting
7. Implement backup strategy for the database

📚 Additional Documentation

• Detailed Docker Documentation: https://docs.docker.com/
• Spring Boot Documentation: https://spring.io/projects/spring-boot
• PostgreSQL Documentation: https://www.postgresql.org/docs/

🆘 Getting Help

If you encounter issues:

1. Check logs: docker compose logs -f
2. Check container status: docker compose ps
3. Try a clean restart: docker compose down -v then docker compose up --build -d

📝 License

See LICENSE file for details.