Get Started with Docker: Install, Pull Ubuntu, and Run Hello World

Goal

Install and start Docker, download an Ubuntu base image, launch a container, and output “hello world”.

Installation

Docker requires a Linux kernel 3.8 or newer. On a CentOS 7 system the Docker package is available in the extras repository, so it can be installed directly with yum: sudo yum install -y docker Docker also runs on CentOS 6 (via EPEL) and on Windows/macOS with a virtual machine and Boot2Docker.

Start the Service

Start Docker, stop or restart it, and verify the installation: sudo service docker start To stop or restart: sudo service docker start | stop Check the version to confirm the daemon is running: docker version The command should display version information for both the client and server.

Download the Image

Pull the official Ubuntu image from Docker Hub: docker pull ubuntu The ubuntu tag refers to the latest version unless a specific tag is supplied.

List the images stored locally:

docker images

Run a Container

Start an interactive Ubuntu container and open a shell: docker run -i -t ubuntu /bin/bash Inside the container you can execute commands. To display “hello world”: echo 'hello world' The output should be:

hello world