Running a Database

In the previous lesson, we explored the structure of our Spring Boot blog application.

Now we'll set up a PostgreSQL database using Docker Compose, which will serve as the persistent data store for our blog.

This containerized approach ensures consistency across development environments and simplifies database management.

Understanding Docker Compose

Docker Compose is a tool that defines and manages multi-container Docker environments.

For our blog platform, we need a PostgreSQL database server and (optionally) a database management interface.

Docker Compose allows us to define these services in a declarative way using a YAML file.

Creating the Docker Compose File

Let's create a new file named docker-compose.yml in the project root directory with the following content:

services:
  # Our PostgreSQL database
  db:
    # Using the latest PostgreSQL image
    image: postgres:latest
    ports:
      - '5432:5432'
    restart: always
    environment:
      POSTGRES_PASSWORD: changemeinprod!

  # Database management interface
  adminer:
    image: adminer:latest
    restart: always
    ports:
      - 8888:8080

Running the Database

Starting the database requires Docker to be installed and running on your system.

Open a terminal in your project directory and run:

docker-compose up

This command starts both the PostgreSQL database and Adminer.

Accessing the Database

The PostgreSQL database is now accessible on port 5432.

You can access the Adminer interface at http://localhost:8888 with these credentials:

System: PostgreSQL
Server: db
Username: postgres
Password: changemeinprod!

Summary

Docker Compose enables consistent database setup across development environments
PostgreSQL runs in a container, avoiding direct installation on the host system
Adminer provides a web interface for database management
The database automatically restarts if the Docker daemon restarts