What is docker?

Docker is kind of like running virtual machines, but in a more efficient method. Rather than having a virtual machine with their own kernel, services, and operating system, why not just re-use some of the resources of our host computer? So it does that, being very careful to prevent anything running on the container from breaking out.

Docker containers are defined in a “Dockerfile”, and its ubiquity makes it a very easy way of spinning up all sorts of services, inside of a Docker image (which can be copied!). Is 1 million more people watching YouTube tonight? Start up 100 containers or however many is needed to host all of their traffic.

Check if you have it installed already

Run these commands to check if docker is already installed:

sudo docker ps
sudo docker compose ls

Installation (Method 1)

Installation (Longer Method 2);

And to check if it is working:

sudo docker ps
sudo docker compose ls

Make our first service

Make a new directory and go into it, and begin editing docker-compose.yml.

# I'll be using a "docker-test" directory for this
mkdir docker-test
cd docker-test
nano docker-compose.yml

What do we put in it?

version: "3.8"

services:
  whoami:
    image: traefik/whoami:latest
    container_name: whoami
    restart: "no"
    ports:
      - "8080:80"