Let’s start with a simple example.

Example 1: Postgres

docker-compose.yml:

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version: '3.8'

name: project_name # Container Name
services:
  postgres: # Service Name
    image: postgres:latest
    container_name: dushexuezhang-postgres # This isn't important
    environment:
      POSTGRES_USER: TODO
      POSTGRES_PASSWORD: TODO
      POSTGRES_DB: TODO
    ports:
      - "5458:5432"
    volumes:
      - persist_data:/var/lib/postgresql/data
    restart: unless-stopped

volumes:
  persist_data:
    name: dushe_postgres_data # This can be shared between containers
    driver: local

Note that:

  1. Make sure to set name, otherwise, Docker will use folder name as container name.
  2. postgres is the service name, displayed under ‘project_name’ in Docker Desktop. A container can have multiple services.
  3. ports: :, that means your postgres runs on localhost:5458.
  4. volumes is used to persist data.
    • persist_data is an identifier for the volume. It’s like an alias.
    • name is the actual name of the Docker volume, which will be displayed in Docker Desktop.

On Volume name

If you do not specify a name, Docker will use [project_name]_[service_name]_data as the volume name. For example, dushexuezhang_postgres_data. So, I recommend setting a name for your volume.

If you reuse the same name as another container, Docker will reuse the same volume, essentially you get same DB data.

Docker commands

To see all containers, run docker ps.

To see all images, run docker images.

To see all volumes, run docker volume ls.

To remove orphaned volumes, run docker volume prune.