The Atomic Host platform is now replaced by CoreOS. Users of Atomic Host are encouraged to join the CoreOS community on the Fedora CoreOS communication channels.
The documentation contained below and throughout this site has been retained for historical purposes, but can no longer be guaranteed to be accurate.
The application as shipping container metaphor behind the Docker project’s name and logo paints an attractive picture for developers: spawn a container on your local machine, fill it with code, and then ship it off to your far-flung users.
While the app is where the action happens, I can’t help but wonder what sort of ships await our containers when they arrive at the dock. No matter how well you...
Read More »When Project Atomic got off the ground in April, I wrote a blog post about how anyone could Build Your Own Atomic host, based on Fedora 20. Since that time, there have been some changes in the rpm-ostree tooling used to produce these images.
What’s more, there’s a new distro on the block, CentOS 7, that you may wish to build into an Atomic host. Part of what’s great about the Atomic model is the...
Read More »When compared to dynamic sites based on WordPress or Drupal, staticly generated blog and Web sites (like this one) can go a long way toward simplifying deployment and maintenance. There’s no database or server-side code to maintain, and, when paired with a service like Github or Gitlab, you can accept posts or other contributions from anyone, via pull request.
However, while simplifying certain...
Read More »Dockermania has been running wild, and it seems as though there’s an advocate for swapping in the containerization technology wherever we once turned to virtual machines. While Docker won’t (yet) fit the bill in all of these cases, containers are great for trying out new or updated Web applications on your local machine.
Rather than tax your speedy but space-constrained notebook SSD with a library of different virtual machines, you can stack up a series of containers on a single VM.
When WordPress hit its big 4.0 release earlier this month, I fired up an instance of the new Fedora 21 Atomic image alpha on my notebook to check out the new WordPress release, in Dockerized form.
I’ve tried out a lot of different software applications in my time, so I’ve come to appreciate projects and products that make it easy to get up and running quickly and without the need for assembling a whole labful of equipment.
In this vein, the various components that comprise oVirt, the open source virtualization management project, can be piled onto a single piece of hardware in form that works well enough to credibly kick the project’s tires.
Over the past several weeks, teams within the CentOS and Fedora projects have been establishing the processes needed to produce Atomic Host
variants of their respective distributions. If you haven’t already done so, you can check out the latest pre-release Fedora Atomic and CentOS Atomic images.
Now, consuming an OS that partakes in the hotness of atomic system and application management while...
Read More »Atomic hosts include Kubernetes for orchestration and management of containerized application deployments, across a cluster of container hosts. If you’re interested in taking Kubernetes for a spin on an Atomic host, read on!
First, boot into CentOS Atomic host. You ought to be able to use Fedora Atomic as well, but currently, Atomic Fedora comes with an earlier version of kubernetes, so for each of the kubectl commands in this howto, there’s a different kubecfg command, for now.
Back in November, I wrote about how to try out Kubernetes, the open source system for managing containerized applications across multiple hosts, using Atomic Hosts. In that post, I walked through a deployment of the Kubernetes project’s multicontainer Hello World
application.
This time, I thought I’d explore running a more real-world application on Kubernetes, while looking into a few alternate methods of spinning up a Kubernetes cluster.
For the application, I picked Gitlab, an open source code collaboration platform that resembles and works like the popular Github service. I run a Gitlab instance internally here at work, and I wanted to explore moving that application from its current, virtual machine-based home, toward a shiny new containerized future.
Atomic hosts are meant to be as slim as possible, with a bare minimum of applications and services built-in, and everything else running in containers. However, what counts as your bare minimum is sure to differ from mine, particularly when we’re running our Atomic hosts in different environments.
For instance, I’m frequently testing and using Atomic hosts on my oVirt installation, where it’s handy...
Read More »
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.
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.
I’ll cover how to reconfigure your Docker installation w/ better-performing storage, but first, a bit of background:
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.
Docker and CentOS 6 have never been a terrific fit, which shouldn’t be surprising considering that the version of the Linux kernel that CentOS ships was first released over three years before Docker’s first public release (0.1.0). The OS and kernel version you use matter a great deal, because with Docker, that’s where all your contained processes run.
With a hypervisor such as KVM, it’s not uncommon or problematic for an elder OS to host, through the magic of virtualization, all manner of bleeding-edge software components. In fact, if you’re attached to CentOS 6, virtualization is a solid option for running containers in a more modern, if virtual, host.
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.
The up-and-running part of the walkthrough amounts to issuing just three docker run commands:
# docker run --net=host -d gcr.io/google_containers/etcd:2.0.9 /usr/local/bin/etcd --addr=127.0.0.1:4001 --bind-addr=0.0.0.0:4001 --data-dir=/var/etcd/data
# docker run --net=host -d -v /var/run/docker.sock:/var/run/docker.sock gcr.io/google_containers/hyperkube:v0.21.2 /hyperkube kubelet --api_servers=http://localhost:8080 --v=2 --address=0.0.0.0 --enable_server --hostname_override=127.0.0.1 --config=/etc/kubernetes/manifests
# docker run -d --net=host --privileged gcr.io/google_containers/hyperkube:v0.21.2 /hyperkube proxy --master=http://127.0.0.1:8080 --v=2
Now, this isn’t as simple as rattling off a single command from memory, but we can’t have everything…
…or can we?
Through the magic of a couple tools we’ve been working on here at Project Atomic, we can get up and running with the upstream kubernetes project’s containerized install method using a single command like this:
# atomic run jasonbrooks/kubernetes-atomicapp
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.
Referencing the sample cockpitws.service file from Matt’s post, and using cloud-init’s cloud-config-write-files functionality, I started out with this service file:
Big news, fans of all things Atomic – the CentOS Project’s Atomic SIG has released an updated CentOS Atomic Host system tree and image set, which includes Kubernetes v1:
Next week, on Tuesday, September 22nd, the Fedora Cloud and CentOS Atomic special interest groups will be dabbling in test day fusion to put each projects’ Atomic Host Images through their paces.
On the Fedora side, we’ll be testing images based on the upcoming Fedora 23. On the CentOS side, we’ll test images from our latest release, as well as one or more development images featuring newer components atop the CentOS 7 base.
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.
The CentOS Atomic Host train rolls on, with an updated filesystem tree and new set of deployment/installation images:
Read More »Today we’re announcing an update to CentOS Atomic Host (version 7.20151001), a lean operating system designed to run Docker containers, built from standard CentOS 7 RPMs, and tracking the component versions included in Red Hat Enterprise Linux Atomic Host.
CentOS Atomic Host is...
The CentOS Atomic SIG has released an updated filesystem tree and new set of deployment/installation images, featuring updates to docker and atomic, among other components.
Check out the details below, and stay tuned for the next CentOS Atomic Host update, which should arrive soon after the main CentOS Project finishes building its next major release.
The CentOS Atomic SIG has released new images and an updated filesystem tree for CentOS Atomic Host. This includes a patched glibc and a refreshed set of Kubernetes packages, among other updates. All users running CentOS Atomic Host in production should update as soon as possible.
An updated version of CentOS Atomic Host (version 7.20160224) is now available for download. CentOS Atomic Host is a lean operating system designed to run Docker containers, built from standard CentOS 7 RPMs, and tracking the component versions included in Red Hat Enterprise Linux Atomic Host.
An updated version of CentOS Atomic Host (version 7.20160404) is now available for download, featuring significant updates to Docker (1.9.1) and to the atomic run tool.
CentOS Atomic Host is a lean operating system designed to run Docker containers, built from standard CentOS 7 RPMs, and tracking the component versions included in Red Hat Enterprise Linux Atomic Host.
Version 1.9 of the atomic...
Read More »Last week, the CentOS Atomic SIG released an updated version of CentOS Atomic Host (tree version 7.20160707), featuring updated versions of docker and the atomic run tool.
CentOS Atomic Host includes these core component versions:
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.
Note: Due to an issue with the image-building process, the current Fedora Atomic Host images include an older version of the system tree. Be sure to atomic host upgrade to get the latest set of components. The next two-week media refresh will include an up-to-date tree.
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.
The atomic hosts from CentOS and Fedora earn their atomic
namesake by providing for atomic, image-based system updates via rpm-ostree, and atomic, image-based application updates via docker containers.
This system
vs application
division isn’t set in stone, however. There’s room for system components to move across from the somewhat rigid world of ostree commits to the freer-flowing container side.
In particular, the key atomic host components involved in orchestrating containers across multiple hosts, such as flannel, etcd and kubernetes, could run instead in containers, making life simpler for those looking to test out newer or different versions of these components, or to swap them out for alternatives.
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 7.20161006), which offers users the option of substituting the host’s default docker 1.10 container engine with a more recent, docker 1.12-based version, provided via the docker-latest package.
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.
Want to help make Fedora Atomic Host even better? Join us next week for the Fedora Cloud Test Day, where we’ll be banging on the Atomic Host image for Fedora. As always, we’re looking for many hands to help put the release through its paces.
A new CentOS Atomic Host release (7.20170117), based on CentOS 7.1611, is now available. Beyond the rebase to the new CentOS version, the biggest change in this release is the removal of the kubernetes-master package from the image, a change that we’ve inherited from RHEL Atomic.
An updated version of CentOS Atomic Host (tree version 7.20170209), is now available, including significant updates to docker (version 1.12.5), kubernetes (version 1.4) and etcd (version 3.0.15).
CentOS Atomic Host is a lean operating system designed to run Docker containers, built from standard CentOS 7 RPMs, and tracking the component versions included in Red Hat Enterprise Linux Atomic Host...
Read More »An updated version of CentOS Atomic Host (tree version 7.20170405), is now available, including significant updates to kubernetes (version 1.5.2), etcd (version 3.1) and flannel (version 0.7).
I’ve blogged here in the past about different ways of running Kubernetes and its dependencies in containers. In that post, I discussed how you could side-step the chicken-and-egg complexities of trying to use Docker to run components on which Docker itself relies by running Flannel and etcd in system containers, which don’t rely on Docker to run.
Recently, I’ve been working on running Kubernetes in system containers, too. Since I was already running etcd and Flannel in system containers, I could save on a bit of storage by having Flannel, etcd, and Kubernetes all share the same image in the ostree-based storage that system containers use.
An updated version of CentOS Atomic Host (tree version 7.20170428), is now available, featuring the option of substituting the host’s default docker 1.12 container engine with a more recent, docker 1.13-based version, provided via the docker-latest package.
Recently, I’ve been experimenting with running Kubernetes in system containers, and those tests led me to wonder whether I could use system containers as a means of working around the issues I’ve experienced installing kubeadm, the simple-to-use tool for bootstrapping kubernetes clusters, on an atomic host.
On a regular CentOS or Fedora host, using kubeadm is a matter of installing rpms for the kubelet, kubectl, kubeadm itself, and for a set of Kubernetes networking tools, kubernetes-cni. On an atomic host, rpm-ostree package layering allows for installing rpms, but if existing kube rpms are already part the atomic host image, as they are for Fedora Atomic Host, you won’t be able to install the prescribed upstream kube versions. And even on a host without built-in kubernetes, like CentOS Atomic Continuous, rpm-ostree won’t abide rpm content stored in /opt.
The Fedora Project ships new Fedora Server and Fedora Workstation releases at roughly six-month intervals, and maintains each release for around thirteen months. So Fedora N is supported by the community until one month after the release of Fedora N+2. Since the first Fedora Atomic Host shipped, as part of Fedora 21, the project has maintained separate ostree repositories for both of the active...
Read More »An updated version of CentOS Atomic Host (tree version 7.1705), is now available.
In this release, we’ve modified the versioning scheme we’re using for
the ostree repo to match the monthly major-version.YYMM numbering that
the rest of CentOS uses for its monthly releases. Moving forward, we
plan on releasing CentOS Atomic host on a monthly schedule. The next
CentOS Atomic Host release that will roll up all of June’s software
updates, will be versioned 7.1706, and so on in the following months.
We also intend to add an additional ostree ref to our repository,
called updates,
which will enable users to access the latest
packages as they become available. Stay tuned during the coming weeks
for more information on that option.
We’ve upgraded the ostree repository for CentOS Atomic Host (v7.1705.1) to
include updates of the packages affected by the Stack Guard
vulnerability.
Please update your CentOS Atomic Host at the next opportunity, with the command:
atomic host upgrade --reboot
An updated version of CentOS Atomic Host (tree version 7.1706), is now available.
Last week, the CentOS Atomic SIG released an updated version of CentOS Atomic Host (7.1707), a lean operating system designed to run Docker containers, built from standard CentOS 7 RPMs, and tracking the component versions included in Red Hat Enterprise Linux Atomic Host.
The release, which came as part of the monthly CentOS release stream, was a modest one, including only a single glibc bugfix update. The next Atomic Host release will be based on the RHEL 7.4 source code and will include support for overlayfs container storage, among other enhancements.
Fedora 26 Atomic Host relies on Kubernetes for automating deployment, scaling, and operations of application containers across clusters of hosts.
Getting up and running with Kubernetes on Fedora Atomic Host involves installing Kubernetes (or sticking with the version of the software that’s currently baked into the images), and then configuring a cluster. This can be done manually, with the Kubeadm utility, or with Ansible scripts (among other methods).
The CentOS Atomic SIG has released an updated version of CentOS Atomic Host (7.1708), 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, which is based on the RHEL 7.4 source code, includes an updated kernel that supports overlayfs container storage, among other enhancements.
Starting with Fedora 27 Atomic Host, the RPMs for Kubernetes, Flannel and Etcd are no longer included in the host’s image, but are installable instead either as system containers or via package layering.
Last week, the CentOS Atomic SIG released an updated version of CentOS Atomic Host (7.1711), 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 rolls up a handful of minor CentOS updates from the past month. The core Atomic component versions are unchanged from those in the previous release (7.1710).
The CentOS Atomic SIG has released an updated version of CentOS Atomic Host (7.1712), 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 updated kernel, linux-firmware and microcode_ctl packages to address recent security advisories, alongside other minor updates that shipped during the month of December.