The devel tree of CentOS Atomic Host, which features a trimmed-down system image that leaves out kubernetes and related system components, is a great place to experiment with alternative methods of running these components, and swapping between them.
Last week, the CentOS Atomic SIG released an updated version of CentOS Atomic Host (tree version 7.20160818), featuring support for rpm-ostree package layering.
CentOS Atomic Host is available as a VirtualBox or libvirt-formatted Vagrant box, or as an installable ISO, qcow2 or Amazon Machine image. Check out the CentOS wiki for download links and installation instructions, or read on to learn more about what’s new in this release.
In June, the oVirt Project shipped version 4.0 of its open source virtualization management system. With a new release comes an update to this howto for running oVirt together with Gluster storage using a trio of servers to provide for the system’s virtualization and storage needs, in a configuration that allows you to take one of the three hosts down at a time without disrupting your running VMs.
One of the biggest new elements in this version of the howto is the introduction of gdeploy, an Ansible based deployment tool that was initially written to install GlusterFS clusters, but that’s grown to take on a bunch of complementary tasks. For this process, it’ll save us a bunch of typing and speed things up significantly.
This week, the Fedora Project released updated images for its Fedora 24-based Atomic Host. Fedora Atomic Host is a leading edge operating system designed around Kubernetes and Docker containers.
Fedora Atomic Host images are updated roughly every two weeks, rather than on the main six-month Fedora cadence. Because development is moving quickly, only the latest major Fedora release is supported.
A single Atomic Host is a fine place to run your containers, but these hosts are much more fun when bunched into clusters, a task that we can manage with the help of Kubernetes.
There are a lot of great guides for setting up a kubernetes cluster, but my favorite involves ansible and vagrant, and lives in the kubernetes contrib repository on Github.
This install method can be used with the libvirt, virtualbox or openstack vagrant providers. You can also use the ansible scripts on their own, if vagrant isn’t your thing.
Fedora 22’s Atomic Host dropped most of packages for the web-based server UI, cockpit, from its system tree in favor of a containerized deployment approach. Matt Micene blogged about running cockpit-in-a-container with systemd, but people have expressed interest in learning how to start this container automatically, with cloud-init.
Kubernetes, the open source orchestration system for Docker containers, is a fast-moving project that can be somewhat complicated to install and configure, especially if you’re just getting started with it.
Fortunately, the project maintains some really well-done getting started guides, the simplest of which steps you through running Kubernetes, in Docker containers, on a single host.
Recently, I blogged about docker-on-loopback-storage woes and workarounds – a topic that came up during several conversations I had at last month’s Dockercon. Another frequently-discussed item from the conference involved Docker on CentOS 6, and whether and for how long users can count on running this combination.
I’ve heard negative things about the Fedora|CentOS Docker storage configuration in the past, and while manning the Red Hat booth in San Francisco at DockerCon last week, I spoke to a number of people who’ve experienced these storage issues themselves.
Much of the trouble, I think, boils down to how Docker in Fedora and CentOS have shipped with a storage configuration that optimizes for a convenient getting started experience that can lead to inconvenience down the road.
Just over a week ago, I headed to the outskirts of San Francisco’s Financial District to attend Container Camp, a one-day, single-track conference focused primarily on the Docker ecosystem.
The Container Camp lineup included a nice mix of project talks and real user stories that left me looking forward to attending the next time the crew comes to town, and thinking back on the key issues raised during the event.