How To Install Docker on Ubuntu 16.04

Docker is an open-source software that helps to deploy, run applications in a container. The containers are like a virtual machine but consume fewer resources, easy to manage and will always run the same regardless of the operating environment it is running in.

Docker uses cgroups and namespace to allow the independent containers to run within a single Linux instance.

This guide will help you to install Docker on Ubuntu 16.04.

Install Docker On Ubuntu 16.04

Docker is now available in two editions,

• Community Edition (CE)
• Enterprise Edition (EE)

Here, we will install Docker Comunity Edition (CE).

Prerequisites

Uninstall older versions of Dockers, named docker or docker-engine along with associated dependencies. If your system does not have a docker package, skip the below step.

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

Contents such as images, volumes, and networks under /var/lib/docker/ are preserved.

Setup Docker Repository

Update the repository cache.

sudo apt-get update

Install the below packages to ensure the apt work with https method, and that CA certificates are installed.

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

Add the GPG key for the Docker repository on your system.

wget https://download.docker.com/linux/ubuntu/gpg 

sudo apt-key add gpg

Now, add the official Docker repository by running the following command in the terminal.

echo "deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable" | sudo tee /etc/apt/sources.list.d/docker.list

Update the apt database.

sudo apt-get update

Make sure you are installing the docker from the official repository, not from the default Ubuntu repositories.

sudo apt-cache policy docker-ce

You should see the output like below, should have Docker repository details.

docker-ce:
  Installed: (none)
  Candidate: 5:19.03.5~3-0~ubuntu-xenial
  Version table:
     5:19.03.5~3-0~ubuntu-xenial 500
        500 https://download.docker.com/linux/ubuntu xenial/stable amd64 Packages
     5:19.03.4~3-0~ubuntu-xenial 500
        500 https://download.docker.com/linux/ubuntu xenial/stable amd64 Packages
     5:19.03.3~3-0~ubuntu-xenial 500
        500 https://download.docker.com/linux/ubuntu xenial/stable amd64 Packages

Install Docker

Now, install the Docker using the following command.

sudo apt-get -y install docker-ce

Now you have Docker installed on your machine, start the Docker service in case if it is not started automatically after the installation

sudo systemctl start docker

sudo systemctl enable docker

Run a docker container to verify the Docker installation

sudo docker run hello-world

You should see output like below; this confirms that Docker is correctly installed.

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
1b930d010525: Pull complete 
Digest: sha256:4fe721ccc2e8dc7362278a29dc660d833570ec2682f4e4194f4ee23e415e1064
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/

Allow Non-root user to run Docker

By default, you would require root privilege to run docker commands. To avoid this, I had been using docker commands with sudo. If you want to allow non-root users to run Docker containers, follow the below steps to give them privileges to run a Docker.

Create a group called docker if it does not exist.

sudo groupadd docker

Add your user to the docker group, replace raj with your username.

sudo useradd -m raj

Add a user to the docker group.

sudo usermod -aG docker raj

Log out and log back in.

Now, you should now be able to run Docker commands without prefixing sudo.

$ docker run hello-world

Interested Topics

Docker Basic Topics

1: Top Important Docker Commands – Working with Docker Containers

2: Working with Docker Images – Building Docker Images

3: How to Build Docker Images with DockerFile

Docker Advanced Topics

1: How to Setup Docker Private Registry on CentOS 7

2: How to Install and Configure Docker Swarm on CentOS 7

Conclusion

That’s All. Please share your thoughts in the comments section.