Install Docker on CentOS

7min
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. 
Linux
$ sudo yum remove docker \
                  docker-client \
                  docker-client-latest \
                  docker-common \
                  docker-latest \
                  docker-latest-logrotate \
                  docker-logrotate \
                  docker-engine
$ 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.
Linux
$ sudo yum install -y yum-utils

$ sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo
$ 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.
Linux
$ sudo yum install docker-ce docker-ce-cli containerd.io
$ 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.
Linux
$ sudo systemctl start docker
$ sudo systemctl start docker
﻿
Now, start a container to check that Docker is installed correctly. 
Linux
$ sudo docker run hello-world
$ 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.
Linux
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

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.
Linux
$ sudo groupadd docker
$ sudo groupadd docker
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Then add the non-root user to the group.
Linux
$ sudo usermod -aG docker $USER
$ sudo usermod -aG docker $USER
﻿
With all that done, you've got Docker set up and ready to use.
Creating a Dockerhub account
Install Docker on Ubuntu or Debian