How to install Docker on Ubuntu 18.04 ?

The steps below shows how to install docker on x86_64 bit Ubuntu desktop and have independent Ubuntu shell inside docker.

[ Note: docker works only with 64 bit Ubuntu, hence if you have 32 bit Ubuntu machine, it will not work ]

If you have any nonworking traces of docker, remove it using below command,

$ sudo apt-get remove docker docker-engine

Type below commands on your Ubuntu terminal,

$ sudo apt-get update

$ sudo apt install docker.io

above command will install docker command, you can check using “which docker” command and you would see it installed as /usr/bin/docker

Next we need to install docker engine “docker-ce” as,

$ sudo apt-get install apt-transport-https ca-certificates curl gnupg-agent software-properties-common

Add Docker’s official GPG key

$ curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

$ sudo apt-key fingerprint 0EBFCD88
pub   rsa4096 2017-02-22 [SCEA]
      9DC8 5822 9FC7 DD38 854A  E2D8 8D81 803C 0EBF CD88
uid           [ unknown] Docker Release (CE deb) <docker@docker.com>
sub   rsa4096 2017-02-22 [S]

$ sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

$ sudo apt-get update

Now, you can verify that docker-ce package is available to install as,

$ sudo apt search docker-ce
Sorting... Done
Full Text Search... Done
docker-ce/bionic 5:19.03.13~3-0~ubuntu-bionic amd64
  Docker: the open-source application container engine

docker-ce-cli/bionic 5:19.03.13~3-0~ubuntu-bionic amd64
  Docker CLI: the open-source application container engine

Now, lets check if there is any docker image currently running, which can be checked as,

$ sudo docker ps
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

As, you can see above everything is empty, means no image is currently installed..

Now, install the package as,

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

above command will install docker engine and start the service which can be verified as,

$ ps -ax | grep docker
 2188 ?        Ssl    0:00 /usr/bin/dockerd -H fd:// --containerd=/run/containerd/containerd.sock

Verify that Docker is installed correctly by running the hello-world image.

$ sudo docker run hello-world

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
0e03bdcc26d7: Pull complete 
Digest: sha256:8c5aeeb6a5f3ba4883347d3747a7249f491766ca1caa47e5da5dfcf6b9b717c0
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
    (amd64)
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.

To try something more ambitious, you can run an Ubuntu container with:
 $ docker run -it ubuntu bash

Share images, automate workflows, and more with a free Docker ID:
 https://hub.docker.com/

For more examples and ideas, visit:
 https://docs.docker.com/get-started/

as you see, it pulled the “hello-world” docker image and installed and run this to show the message “Hello from Docker !” which shows you have successfully installed docker on your ubuntu machine.

You can see the “hello-world” docker image installed as,

$ sudo docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
hello-world         latest              bf756fb1ae65        9 months ago        13.3kB