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Short overview of how to set up a Fedora CoreOS (FCOS) instance with a simple single node Kubernetes cluster using kubeadm, CRI-O as the container runtime and Flannel as the CNI network provider.

In computer science recursion is the act of solving a problem with intermediate results of smaller instances of the same problem. A function used to solve a problem is therefore calling itself within its own definition. This concept is usually supported by most programming languages in addition to the imperative style of programming, which uses control structures such as for and while loops. Some functional programming languages even support recursion as the only method of problem solving. This article is about the definition of recursion in lambda calculus.

After introducing fundamentals of the lambda calculus in a previous article, along with demonstrations how it can be used for basic arithmetic, the following text has the goal to show how Boolean algebra is expressed in this formal system. Based on the definitions of true and false further basic operations of Boolean algebra can be derived, which then leads to one important aspect in programming: expressing conditionals.

Lambda calculus is a formal system to study computable functions based on variable binding and substitution. Introduced in the 1930s by Alonzo Church, it is (in its typed form) the fundamental concept of functional programming languages like Haskell and Scala. Although the topic might seem very theoretical, some basic knowledge in lambda calculus can be very helpful to understand these languages, and where they originated from, much better. The goal of this article is to introduce some basic concepts of lambda calculus, which later on can be mapped to real world usage scenarios with functional programming languages.

Fedora CoreOS (FCOS), and the used configuration system Ignition, does currently not support injecting the needed configuration file via so called config-drives. It is required to host this file on a separate web server or to use a custom data injection mechanism of one of the supported cloud providers (like user-data from Amazon AWS EC2). As this can be difficult for users with simpler use cases and with no access to external web servers, I want to provide a short overview how to embed the configuration file into the FCOS image itself.

Fedora CoreOS, the new operation system developed by the Fedora community and Red Hat, finally left the preview phase. As a user of the now deprecated Atomic Hosts (available for Fedora, CentOS, Red Hat Enterprise Linux) a good opportunity to try it out and give some hints how to configure your first working system.

When dealing with modern IT infrastructure the chances are pretty high that you already came in contact with virtualized systems. Be it running a virtual machine on your Linux or Windows computer with software like VirtualBox, using virtualized networks like VPN or working with modern container-based virtualization as provided by tooling such as Docker.

The broad term virtualization can cover a lot of ground and my main focus in this article lies on platform as well as container-based virtualization; with the goal to provide a basic distinction between different virtualization techniques while introducing some key concepts to build upon.