The CentOS Atomic SIG has released an updated version of CentOS Atomic Host (7.1710), a lean operating system designed to run Linux containers, built from standard CentOS 7 RPMs, and tracking the component versions included in Red Hat Enterprise Linux Atomic Host.

This release includes an updated version of rpm-ostree that allows for more flexibility when using rpm-ostree's package layering features.

CentOS Atomic Host includes these core component versions:

• atomic-1.19.1-5.git48c224b.el7.centos.x86_64
• cloud-init-0.7.9-9.el7.centos.2.x86_64
• docker-1.12.6-61.git85d7426.el7.centos.x86_64
• etcd-3.2.7-1.el7.x86_64
• flannel-0.7.1-2.el7.x86_64
• kernel-3.10.0-693.5.2.el7.x86_64
• kubernetes-node-1.5.2-0.7.git269f928.el7.x86_64
• ostree-2017.11-1.el7.x86_64
• rpm-ostree-client-2017.9-1.atomic.el7.x86_64

Package Layering with rpm-ostree

Using rpm-ostree package layering, it is possible to dynamically add more packages onto the system that are not part of the commit composed on the server. These additional "layered" packages are persistent across upgrades, rebases, and deploys. If a package you wish to layer conflicts with a package already in the atomic host image, a set of recently-added "override" commands can help resolve the conflict.

For instance, the "origin-clients" package can be used to quickly stand up an OpenShift Origin install using the command oc cluster up, but this package conflicts with the "kubernetes-client" package that comes baked into the CentOS Atomic Host image. You can use package layering to configure the repository containing the "origin-clients" rpm, to remove the conflicting kubernetes packages, and to install "origin-clients."

# rpm-ostree install centos-release-openshift-origin36
# rpm-ostree ex livefs
# rpm-ostree ex override remove kubernetes-client kubernetes-node
# rpm-ostree install origin-clients -r

Download CentOS Atomic Host

CentOS Atomic Host is available as a VirtualBox or libvirt-formatted Vagrant box, or as an installable ISO, qcow2 or Amazon Machine image. For links to media, see the CentOS wiki.

Upgrading

If you're running a previous version of CentOS Atomic Host, you can upgrade to the current image by running the following command:

# atomic host upgrade

Release Cycle

The CentOS Atomic Host image follows the upstream Red Hat Enterprise Linux Atomic Host cadence. After sources are released, they're rebuilt and included in new images. After the images are tested by the SIG and deemed ready, we announce them.

Getting Involved

CentOS Atomic Host is produced by the CentOS Atomic SIG, based on upstream work from Project Atomic. If you'd like to work on testing images, help with packaging, documentation -- join us!

The SIG meets every two weeks as part of the Project Atomic community meeting at 16:00 UTC on Monday in the #atomic channel. You'll often find us in #atomic and/or #centos-devel if you have questions. You can also join the atomic-devel mailing list if you'd like to discuss the direction of Project Atomic, its components, or have other questions.

Getting Help

If you run into any problems with the images or components, feel free to ask on the centos-devel mailing list.

Have questions about using Atomic? See the atomic mailing list or find us in the #atomic channel on Freenode.