Introduction

Docker is an open-source containerization platform that developers use to build, run, and package applications for deployment using containers. Unlike virtual machines, Docker containers offer: OS-level abstraction with optimum resource utilization. Interoperability

Prerequisites

• Ubuntu with 20.04 or WSL environment

• Nothing else 😀

Althought this guide is for Ubuntu 20.04 and WSL , it should work for all other version of Ubuntu also.

Installing Docker

First, we need to uninstall the older version of docker.

Uninstalling Docker

sudo apt-get remove docker docker-engine docker.io containerd runc

It's ok if you get output like below.

Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package docker-engine

Installing Methods

There are many ways to install docker, but we are going to use the recommended repository method.

Set up repository

• Update apt package and install necessary tools

  sudo apt-get update
  sudo apt-get install  ca-certificates  curl  gnupg  lsb-release
  

• Add Docker’s official GPG key

  curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg
  

• Add docker repository

  echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu \
  $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
  

Install Docker engine

• Update apt package and install docker engine

  sudo apt-get update
  sudo apt-get install docker-ce docker-ce-cli containerd.io
  

• Start Docker service

  sudo service docker start
  

• Verify if Docker is installed correctly

  sudo docker run hello-world
  

  If you get something like Hello from Docker! This message shows that your installation appears to be working correctly. that's mean you have installed docker.

Notice how you have to run docker with sudo command. It is not recommended running docker with sudo. To run docker without sudo we will add our current user to docker group, that way we can run docker without sudo

To create the docker group and add your user:

• Create the docker group.

  sudo groupadd docker
  

• Add your user to the docker group.

  sudo usermod -aG docker $USER
  

  Now log out and log in again and try to run hello-world image without sudo.

Installing docker-compose

• We will download docker-compose from repository and manually installing it.

  sudo curl -L "https://github.com/docker/compose/releases/download/v2.1.1/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
  

At the time of writing docker-compose v2.1.1 is latest. You can check latest version and modify above command.

• Add appropriate execution permission to docker compose

  sudo chmod +x /usr/local/bin/docker-compose
  

• Verify docker-compose installation

  docker-compose version
  

Deploying sample service

We will be deploying containous/whoami container with docker and docker-compose for testing

Deploying using docker

• Run below command to deploy containous/whoami container

  docker run -d -p 8080:80 --name whoami containous/whoami
  

• Now check if our container is running

  docker ps
  

  If you get something like below image then you are on right path

• Now we will send api request to this container

  curl  localhost:8080/api
  

  You should get something like this

  {"hostname":"b1b7e7b79c89","ip":["127.0.0.1","172.17.0.2"],"headers":{"Accept":["*/*"],"User-Agent":["curl/7.68.0"]},"url":"/api","host":"localhost:8080","method":"GET"}
  

• Let's remove this container. First get your container id using docker ps command.

  docker stop b1b7e7b79c89
  docker rm b1b7e7b79c89
  

  Change b1b7e7b79c89 with your container ID.

Deploying using docker-compose

Now we will deploy same container using docker-compose.

• Create docker-compose.yaml

  touch docker-compose.yaml
  

• edit docker-compose.yaml

  nano docker-compose.yaml
  

  Now paste below content

  version: "3.3"
  services:
  whoami:
    image: "containous/whoami"
    container_name: "whoami"
    ports:
     - 8080:80
  

• Now run docker-compose

  docker-compose up -d
  

  Verify our container is running or not using docker ps

• Send api request using curl

  curl  localhost:8080/api
  

  You should see a reply similar to above. This means our container is running correctly.

• Stop container.

  docker-compose down
  

That's it, you have successfully installed Docker and docker-compose 🎊💐