Database Connection

In this lesson, we'll set up PostgreSQL using Docker and configure our Spring Boot application to connect to it.

Set Up PostgreSQL with Docker

Docker makes running PostgreSQL simple and consistent across different development environments. Let's create a docker-compose.yml file to define our database setup:

services:
  db:
    image: postgres:latest
    ports:
      - '5432:5432'
    restart: always
    environment:
      POSTGRES_PASSWORD: changemeinprod!

  adminer:
    image: adminer:latest
    restart: always
    ports:
      - 8888:8080

This configuration sets up two services:

A PostgreSQL database running on port 5432
Adminer, a web-based database management tool, running on port 8888

To start these services, run:

docker-compose up

Configure Spring Boot Database Connection

Our application needs to know how to connect to PostgreSQL. We'll configure this in application.properties:

# Database Connection
spring.datasource.url=jdbc:postgresql://localhost:5432/postgres
spring.datasource.username=postgres
spring.datasource.password=changemeinprod!

# JPA Configuration
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.format_sql=true
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

The database connection properties tell Spring Boot:

Where to find the database (localhost:5432)
Which database to use (postgres)
The login credentials

The JPA configuration enables:

Automatic table creation and updates based on our entity classes
SQL logging for development debugging
PostgreSQL-specific SQL dialect for optimal database interaction

Development Best Practices

When working with databases in development:

Never store real passwords in configuration files
Use environment variables or secure configuration management in production
Consider using database migration tools like Flyway for production deployments
Keep the SQL logging enabled only in development for debugging

Summary

PostgreSQL runs in Docker for consistent local development
Adminer provides a web interface for database management
Spring Boot connects to PostgreSQL using configuration properties
JPA automatically manages database schema changes