Configuring the databases

We continue adding services in docker-compose.yaml. After the Django service, we add the following configuration:

postgresql:
    image: postgres
    environment:
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
      POSTGRES_DB: hello_db
    volumes:
      - ./postgres_data:/var/lib/postgresql/data/
    expose:
      - 5432

In image: postgres, we are using the official PostgreSQL image. It will be automatically downloaded from the official repositories. Next, we configure the environment variables to indicate the user credentials (POSTGRES_USER and POSTGRES_PASSWORD) and the name of the database (POSTGRES_DB). The variables must match those declared in the Django service; otherwise, it will fail to connect....