How to Install Docker on CentOS 7

Docker is a popular software package that creates and manages containers for application development.

The platform creates a uniform interface so that almost any application running on it is compatible with most operating systems. Developing in Docker also speeds up applications, since it shares the kernel and other Linux resources.

This is a guide on how to install Docker on CentOS 7.

Installing from Docker repositories using the yum command is the easiest and most popular method.

In a terminal window, type:

sudo yum check-update

Allow the operation to complete.

The next step is to download the dependencies required for installing Docker.

Type in the following command:

sudo yum install -y yum-utils device-mapper-persistent-data lvm2

The –y switch indicates to the yum installer to answer “yes” to any prompts that may come up. The yum-utils switch adds the yum-config-manager. Docker uses a device mapper storage driver, and the device-mapper-persistent-data and lvm2 packages are required for it to run correctly.

To install the edge or test versions of Docker, you need to add the Docker CE stable repository to your system. To do so, run the command:

sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

A stable release is tested more thoroughly and has a slower update cycle. On the other hand, Edge release updates are more frequent but aren’t subject to as many stability tests.

With everything set, you can finally move on to installing Docker on CentOS 7 by running:

sudo yum install docker

The system should begin the installation. Once it finishes, it will notify you the installation is complete and which version of Docker is now running on your system.

Your operating system may ask you to accept the GPG key. This is like a digital fingerprint, so you know whether to trust the installation.

The fingerprint should match the following format:

060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35

Although you have installed Docker on CentOS, the service is still not running.

To start the service, enable it to run at startup. Run the following commands in the order listed below.

Start Docker:

sudo systemctl start docker

Enable Docker:

sudo systemctl enable docker

Check the status of the service with:

sudo systemctl status docker0

To install a specific version of Docker, start by listing the available releases.

Type the following in your terminal window:

yum list docker-ce --showduplicates | sort –r

The system should give you a list of different versions from the repositories you have enabled above.

Install the selected Docker version with the command:

sudo yum install docker-ce-<VERSION STRING>

The <VERSION STRING>is found in the middle column and is the first part of the alphanumeric code before the hyphen.

Docker installation on CentOS 7 is a bit easier than installing on Ubuntu.

If you followed this guide, you should have successfully installed Docker on your CentOS 7 machine. Now you can explore the wonderful world of Docker.