The latest release of the Red Hat Enterprise Linux distribution 8 does not officially support Docker. Red Hat has built its own tools,
podman, which aim to be compatible with existing docker images and work without relying on a daemon, allowing the creation of containers as normal users, without the need of special permissions (with some limitations: e.g. at the moment of writing, it's still not possible to map host ports to the container without privileges).
Some specific tools, however, are still missing: an equivalent of
docker-compose, for example does not exists yet. In this tutorial we will see how to install and run the original Docker CE on Rhel8 by using the official Docker repository for CentOS7.
- How to enable the docker-ce repository on Rhel8
- How to install docker and docker-compose on Rhel8
Software Requirements and Conventions Used
|Category||Requirements, Conventions or Software Version Used|
|System||Red Hat Enterprise Linux 8|
|Software||Docker version 18.09.2|
|Other||Permission to run command with root privileges.|
|Conventions|| # - requires given linux commands to be executed with root privileges either directly as a root user or by use of |
What is Docker?
Docker is an open source project which allows the creation and distribution of applications inside
containers, which are standardized environments that can be easily replicated, independently from the host system. While in Red Hat Enterprise Linux 7 Docker was officially supported, on the new release of this open source operating system, it has been replaced by a series of other tools developed by Red Hat itself:
podman. By the use of an external repository, however, it's still possible to install Docker CE (Community Edition): in this tutorial we will see how to perform such installation.
Adding the external repository
Since Docker is not available on Rhel8, we need to add an external repository to obtain the software. In this case we will use the official Docker CE CentOS7 repository: this is, at the moment of writing, the only way to install Docker CE on Red Hat Enterprise Linux 8.
The first thing we need to do is to install the
yum-utils package which contains the
$ sudo yum install yum-utils
yum-config-manager utility let us, among the other things, easily enable or disable a repository in our distribution. By default, only the
baseos repositories are enabled on Rhel8; we need to add and enable also the
docker-ce repo. All we need to do to accomplish this task, is to run the following command:
$ sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
We can verify that the repository has been enabled, by looking at the output of the following command:
$ sudo yum repolist -v
The command above will return detailed information about all the enabled repositories. This is what you should see at this point:
Repo-id : docker-ce-stable Repo-name : Docker CE Stable - x86_64 Repo-revision: 1549905809 Repo-updated : Mon 11 Feb 2019 06:23:29 PM CET Repo-pkgs : 30 Repo-size : 618 M Repo-baseurl : https://download.docker.com/linux/centos/7/x86_64/stable Repo-expire : 172,800 second(s) (last: Mon 18 Feb 2019 10:23:54 AM CET) Repo-filename: /etc/yum.repos.d/docker-ce.repo Repo-id : rhel-8-for-x86_64-appstream-beta-rpms Repo-name : Red Hat Enterprise Linux 8 for x86_64 - AppStream Beta (RPMs) Repo-revision: 1542158694 Repo-updated : Wed 14 Nov 2018 02:24:54 AM CET Repo-pkgs : 4,594 Repo-size : 4.9 G Repo-baseurl : https://cdn.redhat.com/content/beta/rhel8/8/x86_64/appstream/os Repo-expire : 86,400 second(s) (last: Mon 18 Feb 2019 10:23:55 AM CET) Repo-filename: /etc/yum.repos.d/redhat.repo Repo-id : rhel-8-for-x86_64-baseos-beta-rpms Repo-name : Red Hat Enterprise Linux 8 for x86_64 - BaseOS Beta (RPMs) Repo-revision: 1542158719 Repo-updated : Wed 14 Nov 2018 02:25:19 AM CET Repo-pkgs : 1,686 Repo-size : 925 M Repo-baseurl : https://cdn.redhat.com/content/beta/rhel8/8/x86_64/baseos/os Repo-expire : 86,400 second(s) (last: Mon 18 Feb 2019 10:23:56 AM CET) Repo-filename: /etc/yum.repos.d/redhat.repo Total packages: 6,310
docker-ce-stable repository is now enabled on our system. The repository contains several versions of the
docker-ce package, to display all of them, we can run:
$ yum list docker-ce --showduplicates | sort -r docker-ce.x86_64 3:18.09.2-3.el7 docker-ce-stable docker-ce.x86_64 3:18.09.1-3.el7 docker-ce-stable docker-ce.x86_64 3:18.09.0-3.el7 docker-ce-stable docker-ce.x86_64 18.06.2.ce-3.el7 docker-ce-stable docker-ce.x86_64 18.06.1.ce-3.el7 docker-ce-stable docker-ce.x86_64 18.06.0.ce-3.el7 docker-ce-stable docker-ce.x86_64 18.03.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 18.03.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.12.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.12.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.09.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.09.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.06.2.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.06.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.06.0.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.03.3.ce-1.el7 docker-ce-stable docker-ce.x86_64 17.03.2.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.03.1.ce-1.el7.centos docker-ce-stable docker-ce.x86_64 17.03.0.ce-1.el7.centos docker-ce-stable
If we try to install
docker-ce, the system will notify us of a broken dependency problem generated when trying to install the latest version of the software (
3.18.09.2-3): since this version requires
containerd.io >= 1.2.2-3, which seems to be not available, the
3.18.09-2 version will be automatically selected and installed instead:
$ sudo yum install docker-ce Problem: package docker-ce-3:18.09.2-3.el7.x86_64 requires containerd.io >= 1.2.2-3, but none of the providers can be installed - cannot install the best candidate for the job - package containerd.io-1.2.2-3.3.el7.x86_64 is excluded - package containerd.io-1.2.2-3.el7.x86_64 is excluded ==================================================================================================================================== Package Arch Version Repository Size ==================================================================================================================================== Installing: docker-ce x86_64 3:18.09.1-3.el7 docker-ce-stable 19 M Installing dependencies: containerd.io x86_64 1.2.0-3.el7 docker-ce-stable 22 M docker-ce-cli x86_64 1:18.09.2-3.el7 docker-ce-stable 14 M container-selinux noarch 2:2.73-3.el8+1838+91f7e486 rhel-8-for-x86_64-appstream-beta-rpms 42 k libtool-ltdl x86_64 2.4.6-25.el8 rhel-8-for-x86_64-baseos-beta-rpms 58 k python3-policycoreutils noarch 2.8-9.el8 rhel-8-for-x86_64-baseos-beta-rpms 2.2 M python3-setools x86_64 4.1.1-11.el8 rhel-8-for-x86_64-baseos-beta-rpms 446 k policycoreutils-python-utils noarch 2.8-9.el8 rhel-8-for-x86_64-baseos-beta-rpms 227 k python3-IPy noarch 0.81-22.el8 rhel-8-for-x86_64-baseos-beta-rpms 43 k python3-libsemanage x86_64 2.8-3.1.el8 rhel-8-for-x86_64-baseos-beta-rpms 126 k python3-audit x86_64 3.0-0.5.20180831git0047a6c.el8 rhel-8-for-x86_64-baseos-beta-rpms 85 k libcgroup x86_64 0.41-19.el8 rhel-8-for-x86_64-baseos-beta-rpms 70 k checkpolicy x86_64 2.8-1.el8 rhel-8-for-x86_64-baseos-beta-rpms 337 k tar x86_64 2:1.30-4.el8 rhel-8-for-x86_64-baseos-beta-rpms 838 k Enabling module streams: container-tools 1.0 Skipping packages with broken dependencies: docker-ce x86_64 3:18.09.2-3.el7 docker-ce-stable 19 M Transaction Summary ==================================================================================================================================== Install 14 Packages Skip 1 Package Total download size: 59 M Installed size: 248 M Is this ok [y/N]:
As soon as we confirm the installation, the package and its dependencies will be downloaded and installed on our system.
Start and enable the docker daemon
docker-ce is installed, we must start and enable the docker daemon, so that it will be also launched automatically at boot. The command we need to run is the following:
$ sudo systemctl enable --now docker
At this point, we can confirm that the daemon is active by running:
$ systemctl is-active docker active
Similarly, we can check that it is enabled at boot, by running:
$ systemctl is-enabled docker enabled
Docker compose is a very useful package which let us manage multi-container applications, like for example those based on the
LAMP stack, where each part of the environment (PHP, Apache, MariaDB) is provided by a dedicated container (if you are interested in the subject, take a look at our tutorial about creating a docker-based lamp stack). The package is not available on Rhel8, nor an equivalent exists to be used with the Rhel tools. It's, however, possible to install it in many ways: just keep on reading and decide what suits you best.
The way we should install
docker-compose varies depending on whether we want to install it globally or just for a single user. At the moment of writing, the only way to install it globally is to download the binary from the github page of the project:
$ curl -L "https://github.com/docker/compose/releases/download/1.23.2/docker-compose-$(uname -s)-$(uname -m)" -o docker-compose
Once the binary is downloaded, we move it into
/usr/local/bin and we make it executable:
$ sudo mv docker-compose /usr/local/bin && sudo chmod +x /usr/local/bin/docker-compose
/usr/local hierarchy is not chosen randomly. This directory structure is made to be used for files installed by the local administrator manually (for software compiled from source, for example), in order to ensure separation from the software installed with the system package manager.
Although it's possible for a normal user to run docker-related commands if he is part of the
docker group (the group is automatically created when we install docker-ce), by default they must be executed with root privileges for security reasons. When we need to do the latter, since the
/usr/local/bin directory is not in the root user's
PATH, we either need to call the binary specifying its location or add
/usr/local/bin to the
PATH itself. The first option is the one which I recommend in this case.
If our user is part of the
docker group, and thus it is allowed to run docker commands, and since
docker-compose is available as a python package, we can also install it using
pip, the python package manager. First, make sure pip itself is installed:
$ sudo yum install python3-pip
To obtain docker-compose we run:
$ pip3.6 install docker-compose --user
Please notice that even if would be possible to run pip as root to install a package globally, this is not recommended and highly discouraged.
We installed docker and docker-compose, now to check that everything works as expected, we can try to build an image and run a container: in this case we will use the official
httpd one. All we have to do is to launch the following command:
sudo docker run --rm --name=linuxconfig-test -p 80:80 httpd
httpd image does not exists locally it will be automatically fetched and built. Finally, a container based on it will be launched in the foreground (it will be automatically removed when stopped). If our firewall is configured to allow access to port 80, we should be able to see the
It works! message when we reach our machine ip via browser.
Red Hat Enterprise Linux 8 does not support Docker: on this distribution it has been replaced by Red Hat own tools like
podman, which are compatible with Docker but don't need a server/client architecture to run. Using native tools, where possibile, is always the recommended way to go, but for a reason or another you may still want to install the original Docker.
In this tutorial, we saw how it is possible to install Docker CE on Rhel8, by using the official Docker repository for CentOS7, which is a 100% compatible clone. This is not an ideal solution, but it does work correctly, and, at the moment, is the only possible workaround to use Docker Community Edition on Rhel8.