How To Install Docker on Ubuntu 18.04 & 16.04 LTS

Docker is a container-based application framework, which wraps a specific application with all its dependencies in a container. Docker containers can easily ship to the remote location on start there without making the entire application setup. This tutorial will help you to install Docker on Ubuntu 19.10, 18.04 LTS, and 16.04 LTS systems.

1. Prerequisite

The very first step is to remove any default Docker packages from the system before installing Docker on a Linux VPS. Execute commands to remove unnecessary Docker versions.

sudo apt-get purge docker lxc-docker docker-engine docker.io

Now install some required packages on your system for installing Docker on the Ubuntu system. Run the below commands to do this:

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

2. Setup Docker Repository

Now import dockers official GPG key to verify packages signature before installing them with apt-get. Run the below command on the terminal.

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

After that add the Docker repository on your Ubuntu system which contains Docker packages including its dependencies. You must have to enable this repository to install Docker on Ubuntu.

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

3. Install Docker on Ubuntu

Your system is now ready for Docker installation. Run the following commands to upgrade apt index and then install Docker community edition on Ubuntu.

sudo apt-get update
sudo apt-get install docker-ce

After successful installation of the Docker community edition, the service will start automatically, Use below command to verify service status.

sudo systemctl status docker

Your system is now ready for running Docker containers. Use our Docker Tutorial for Beginners to work with Docker.

4. How to Use Docker

After installation of Docker on Linux. Here are some basic details for searching and downloading Docker images, launching containers, and managing them.

Search Docker Images

First of all search Docker container images from the Docker hub. For example, the below command will search all images with Ubuntu and list as output.

docker search ubuntu

Download Docker Images

Now download the Docker container with the name Ubuntu on your local system using following commands.

docker pull ubuntu

latest: Pulling from library/ubuntu

fa5be2806d4c: Pull complete
b4af4261cb15: Downloading [==>               ] 3.779 MB/70.55 MB
5d358abc5d9c: Download complete
2933d50b9f77: Download complete

Now make sure that the above images have been downloaded successfully on your system. Below command list all images.

docker images

REPOSITORY  TAG            IMAGE ID            CREATED             VIRTUAL SIZE
ubuntu      latest         36248ae4a9ac        7 days ago          188 MB

Launch New Container with Image

Finally, launch a Docker container using an above-downloaded image on your system. The below command will start a new container and provide you access to that container with /bin/bash shell.

docker run -i -t ubuntu /bin/bash

To exit from docker container type CTRL + P + Q. This will leave the container running in the background and provide you host system console. If you used the exit command, it will stop the current container.

After exiting from the Docker container, execute the below command to list all running containers.

docker ps

CONTAINER ID     IMAGE     COMMAND        CREATED        STATUS        PORTS    NAMES
f2582758af13     ubuntu    "/bin/bash"    2 hours ago    Up 2 hours             first_ubuntu

By default Above command will list only running containers. To list all containers (including stopped container) use following command.

docker ps -a

Start/Stop/Attach Container

You can start, stop or attach to any containers with the following commands. To start container use following command.

docker start <CONTAINER_ID>

To stop container use following command.

docker stop <CONTAINER_ID>

To attach to currently running container use following command.

docker attach <CONTAINER_ID>