5.3: YAML Syntax: Translating our Docker Run commands into services

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📚Docker for beginners: The Shipyard
📄 Article

Now that we have a clean project structure (/app, /data, /conf) andDockerCompose is installed, it’s time to learn how to translate your commandsdocker runinto YAML services.

The goal: to move from multiple individual commands to a single configuration file that describes the entire stack.

Reminder: Example of adocker run simple

Suppose we want to start MariaDB:

docker run -d \
  --name mariadb \
  -e MYSQL_ROOT_PASSWORD=secret \
  -v ./data/mariadb:/var/lib/mysql \
  --network monprojet-network \
  mariadb:10.11

For Apache/PHP:

docker run -d \
  --name php-web \
  -p 8080:80 \
  -v ./app:/var/www/html \
  --network monprojet-network \
  php:8.2-apache

You can quickly imagine that if you have 5 or 6 containers, things get complicated.

Translation into YAMLDockerCompose

Here’s how the same services translate intodocker-compose.yml :

services:
  mariadb:
    image: mariadb:10.11
    container_name: mariadb
    environment:
      MYSQL_ROOT_PASSWORD: ${DB_ROOT_PASSWORD}  # récupéré depuis .env
    volumes:
      - ./data/mariadb:/var/lib/mysql
    networks:
      - monprojet-network

  php-web:
    image: php:8.2-apache
    container_name: php-web
    ports:
      - "8080:80"
    volumes:
      - ./app:/var/www/html
    networks:
      - monprojet-network

networks:
  monprojet-network:
    driver: bridge

Explanations

YAML ElementRole
services:Declares all containers (services) in the stack.
image:The imageDockerto use.
container_name:Container name (optional but useful).
environment:Environment variables (you can use .env).
volumes:Mounting local directories into the container.
ports:Host-to-container port mapping.
networks:Definition of the networks used by the container.
networks: At the endDeclaring the network if necessary (bridge, overlay…).

Tip: YAML is read from top to bottom, and each indentation is critical. Two spaces are recommended.

Key points

  • docker rundocker-compose.yml Replaces all your commands.
  • Using.env allows you to avoid hard-coding passwords or ports.
  • YAML is easy to read and edit, making it ideal for versioning your project.
  • You can now launch the entire stack with:
docker compose up -d
  • And stop everything with:
docker compose down

📌 Key takeaways

  • Docker Compose simplifies multi-container management in YAML.
  • Eachdocker run becomes a service in the YAML.
  • Dynamic variables are passed into .env.
  • The folder structure (/app, /data, /conf) integrates naturally into YAML.