Compose

What is Docker Compose?

Docker Compose is a tool used for defining and running multi-container Docker applications. It allows you to manage complex applications with multiple services (containers) using a simple YAML configuration file. With Docker Compose, you can define all the services, networks, and volumes needed for your application in a single file, and then use a single command to start, stop, or manage those services.

Install Docker Compose 

apt install docker-compose

YAML (Yet Another Markup Language)

YAML files are just text files that are used by Docker-Compose for definition of image/container setup. YAML files are a very useful feature of Docker as they all for deployment of containers on any system by just using the YAML file.

YAML files are VERY fussy about their syntax - this includes character positioning.

Basic annotated example;

version: '3.7' # Specifies the Docker Compose version used (e.g., 3.7)

services:
  portainer:  # Defines a service named "portainer"

    container_name: container1  # Names the container instance "container1"

    image: portainer/portainer-ce  # Specifies the Docker image to use (portainer/portainer-ce)

    command: -H unix:///var/run/docker.sock  # Command to execute when the container starts (grants access to Docker socket)

    restart: 'always'  # Automatically restarts the container if it crashes or exits

    ports:  # Defines port mappings between the container and the host machine
      - target: '9000'  # Maps container port 9000
        published: '9000'  # to host port 9000 (can be accessed from the host machine)
        protocol: tcp  # using TCP protocol

      - target: '8000'  # Maps container port 8000
        published: '8000'  # to host port 8000 (can be accessed from the host machine)
        protocol: tcp  # using TCP protocol

    volumes:  # Defines persistent storage for the container
      - type: bind  # Mounts a host directory onto a container directory
        source: /var/run/docker.sock  # Binds the host's Docker socket file
        target: /var/run/docker.sock  # to the container's Docker socket file (grants access within the container)

      - type: bind  # Mounts another host directory onto a container directory
        source: /srv/portainer  # Binds the host's `/srv/portainer` directory
        target: /data/  # to the container's `/data/` directory (for persistent data storage)

Start the container based on YAML file:

docker-compose up --detatch

====================================================================================