Installing Docker on CentOS

Another popular Linux distribution is CentOS, which is a free, enterprise-class distribution that is compatible with Red Hat Enterprise Linux (RHEL). Go through the following easy recipe to install Docker on CentOS 7.x.

Getting ready

The centos-extra repository must be enabled. This is usually enabled by default, but if you disabled it, please enable it again.

Previously, the Docker package had a different name: It was called docker or docker-engine; it is now called docker-ce. We will need to remove any previous Docker versions in order to prevent any conflicts:

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

It is OK if yum reports that none of these packages are installed.

How to do it...

Go through the following steps:

1. Install the required packages:

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

2. Set up the Docker yum repository using the stable channel:

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

3. Optional: Enable the test channel for access to the nightly builds:

        $ sudo yum-config-manager --enable docker-ce-test

4. Install the latest version of docker-ce:

         $ sudo yum install docker-ce

5. If prompted to accept the GPG key, verify that it matches 060A 61C5 1B55 8A7F 742B 77AA C52F EB6B 621E 9F35. If it does, then accept it:

    Retrieving key from https://download.docker.com/linux/centos/gpg
    Importing GPG key 0x621E9F35:
     Userid : "Docker Release (CE rpm) <[e-mail]>"
     Fingerprint: 060a 61c5 1b55 8a7f 742b 77aa c52f eb6b 621e 9f35
     From : https://download.docker.com/linux/centos/gpg
    Is this ok [y/N]: y

6. Start the Docker daemon:

        $ sudo systemctl start docker

7. Verify that the installation worked:

        $ docker container run hello-world

How it works...

The preceding recipe installs Docker on CentOS and all the packages required by it.

There's more...

The default Docker daemon configuration file is located at /etc/docker, which is used while starting the daemon. Here are some basic operations:

• To start the service, enter the following:

    $ sudo systemctl start docker

• To verify the installation, enter the following:

    $ docker info

• To update the package, enter the following:

    $ sudo yum -y upgrade

• To enable the service start at boot time, enter the following:

    $ sudo systemctl enable docker

• To uninstall Docker, enter the following:

        $ sudo yum remove docker-ce

• To stop the service, enter the following:

        $ sudo systemctl stop docker

See also

For more information, check out the CentOS installation document on the Docker website at https://docs.docker.com/install/linux/docker-ce/centos/.