Container microdistributions k3OS and Flatcar

Micro Cures

Similar Methods, Different Targets

Now that the role and function of microdistributions are clear, I will discuss two representatives of this category in detail. Most admins probably will have heard of JeOS (Figure 3) or CoreOS, because these are the microdistributions from established vendors SUSE and Red Hat.

Figure 3: SUSE's JeOS microdistribution is a direct competitor to k3OS and Flatcar.

k3OS and Flatcar, on the other hand, are the underdogs and probably unknown to many administrators. However, the following description does not intend to compare the products, because they are based on different factors and partly address different target groups. Rather, it is a brief overview of the product itself.

k3OS for Kubernetes Lovers

k3OS is especially for users who want to use K3s [3]. If you don't know K3s yet but regularly work in the Kubernetes (K8s) context, you have probably already guessed that the abbreviation has something to do with Kubernetes. K3s is a fully Kubernetes compatible distribution of the orchestrator, which is easier to use, smaller, and comes with fewer dependencies.

K3s also comes with packet filtering rules out of the box, which, according to the developers, improved the security of the entire installation. Last but not least, K3s helps admins where they really need it. One of the most annoying features of Kubernetes is setting up a port share on each Kubernetes worker (kubelet) so that the Kubernetes manager can talk to the kubelets.

K3s exposes the API interface over a websocket tunnel instead, so port sharing is no longer a problem. Anyone in the enterprise who has to deal with firewall constructs and compliance rules will like this feature.

Under the Hood

Additionally, K3s bundles various Kubernetes extensions so that they are ready for use on an ad hoc basis. Containerd and runC serve as runtime environments for the containers, and Flannel takes care of the network in between. CoreDNS, Helm, and Kine are also on board by default. With tools you program in-house, K3s makes it easier to maintain required SSL certificates and manage Etcd as a consensus algorithm.

K3s, however, has had to dump some features to become a lighter weight Kubernetes. The storage drivers, which K8s includes out the box, are missing, as is the functionality to communicate with cloud providers. However, because Kubernetes itself is introducing tweaks and replacing the existing functions with new approaches, this point should not be a problem for most admins.

k3OS is not a fork of an existing Linux distribution, which is quite unusual in itself. Most projects that build microdistributions today take an existing distribution and remove the components that are not necessary from the view of the maintainer. k3OS is basically based on a mixture of an Alpine userland and the Ubuntu 18.04 kernel. The developers have assembled the individual components such that they harmonize as well as possible for k3OS.

However, one thing is evident: The evaluation criteria that apply to classical distributions only play a minor role in microdistributions. Basically, the system just needs to support all the server's hardware, and a recent hardware enablement (HWE) kernel by Ubuntu is certainly not a bad idea for that purpose.

Buy this article as PDF

Express-Checkout as PDF
Price $2.95
(incl. VAT)

Buy ADMIN Magazine

SINGLE ISSUES
 
SUBSCRIPTIONS
 
TABLET & SMARTPHONE APPS
Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Rancher Kubernetes management platform
    Rancher has set up shop as an agile alternative to Red Hat OpenShift as an efficient way to manage Kubernetes clusters. In terms of the architecture, a Rancher setup differs significantly from classic Kubernetes.
  • Rancher manages lean Kubernetes workloads
    The Rancher lightweight alternative to Red Hat's OpenShift gives admins a helping hand when entering the world of Kubernetes, but with major differences in architecture.
  • An interview with CoreOS cofounder Brandon Philips
    CoreOS was cofounded in 2013 by Brandon Philips, a former SUSE Linux kernel developer. Since then, CoreOS has gained fame as a specialized Linux with the focus on clusters and containers. We caught up with Philips at LinuxCon North America to talk about CoreOS, 25 years of Linux, and the new challenges facing the modern IT infrastructure.
  • Safeguard and scale containers
    Security, deployment, and updates for thousands of nodes prove challenging in practice, but with CoreOS and Kubernetes, you can orchestrate container-based web applications in large landscapes.
  • The new OpenShift version 4
    Red Hat launched the brand new OpenShift 4 with a number of changes that might suggest upgrading or even getting your feet wet if you've stayed out of the pool so far.
comments powered by Disqus