[CentOS-devel] New CentOS Atomic Host Available for Download

The CentOS Atomic SIG has released an updated version[1] 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.

[1] https://wiki.centos.org/SpecialInterestGroup/Atomic/Download

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[2], 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.

[2] http://rpm-ostree.readthedocs.io/en/latest/manual/administrator-handbook/#hybrid-imagepackaging-via-package-layering

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[3].

[3] https://wiki.centos.org/SpecialInterestGroup/Atomic/Download

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[4], based on
upstream work from  Project Atomic[5]. If you'd like to work on
testing images, help with packaging, documentation -- join us!

[4] http://wiki.centos.org/SpecialInterestGroup/Atomic
[5] http://www.projectatomic.io/

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[6] mailing list if you'd like to discuss
the direction of Project Atomic, its components, or have other
questions.

[6] https://lists.projectatomic.io/mailman/listinfo/atomic-devel

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.