Install Docker on CentOS

Installing Docker on CentOS is fairly straightforward and only takes a few commands. So let’s go through it step by step.

1. Remove Docker

Before we start, we need to remove any Docker dependencies. If you’ve never installed Docker, don’t worry. You can skip this step.

$ sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-engine

2. Set up the repository

We need to install the yum-utils package. yum-utils gives us the yum-config-manager that we need to set up the repository.

$ sudo yum install -y yum-utils

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

3. Install Docker

With yum-utils installed, we can go ahead and install Docker.

$ sudo yum install docker-ce docker-ce-cli containerd.io

4. Test its working

Now everything is installed, we should test if it’s working. So start Docker.

$ sudo systemctl start docker

Now, start a container to check that Docker is installed correctly.

$ sudo docker run hello-world

5. Add non-root users

You’ll notice that if you want to start Docker as a non-root user, you’ll probably run into this error.

Got permission denied while trying to connect to the Docker daemon socket at unix:///var/run/docker.sock: Get http://%2Fvar%2Frun%2Fdocker.sock/v1.40/containers/json: dial unix /var/run/docker.sock: connect: permission denied

Don’t worry. There’s an easy fix for that. First, let’s create the Docker group.

$ sudo groupadd docker

Then add the non-root user to the group.

$ sudo usermod -aG docker $USER

With all that done, you’ve got Docker set up and ready to use.