Ah, it sounds like you're referring to Docker Compose, a tool that helps you define and run multi-container Docker applications. It allows you to define the services, networks, and volumes required for your app in a simple YAML file, making it easier to orchestrate multiple containers.

Here’s a basic rundown of how Docker Compose works:

1. Create a docker-compose.yml file: This file describes the services that are part of your app. Each service is typically a Docker container.
2. Define services: In the docker-compose.yml, you can specify which Docker images to use, environment variables, volumes, and networks for each service.
3. Run your app: After creating the docker-compose.yml file, you can use commands like docker-compose up to start all the services defined in that file.

Basic Example of docker-compose.yml

Here's a simple example where you might have a web service (using Nginx) and a database service (using MySQL):

yaml
version: '3.8'services:  web:    image: nginx:latest    ports:      - "80:80"    volumes:      - ./html:/usr/share/nginx/html    networks:      - mynetwork    db:    image: mysql:5.7    environment:      MYSQL_ROOT_PASSWORD: example    networks:      - mynetworknetworks:  mynetwork:    driver: bridge

Key Points in the Example:

• services: Defines the containers you want to run (e.g., web and db).
• image: Specifies which Docker image to use.
• volumes: Mounts local files or directories into the container.
• ports: Exposes ports for external access.
• networks: Configures the containers to communicate with each other.

Running Docker Compose:

Once your docker-compose.yml file is ready, you can start the services with:

bash
docker-compose up

This will pull the necessary images and start the containers. You can also add the -d flag to run them in detached mode (in the background):

bash
docker-compose up -d

Stopping Docker Compose:

To stop and remove all containers defined in the docker-compose.yml file:

bash
docker-compose down

Why Use Docker Compose?

• Multiple containers: It simplifies managing multi-container applications.
• Reusability: You can define your environment once, and it can be spun up on any machine with Docker Compose.
• Consistency: It ensures that the environment is identical across all stages (development, testing, production).