Open Sourcerers
This guide will show you how to run the newly GA’ed bits of MicroShift on a Raspberry Pi 4 using Fedora IoT 38 or 39. It can announce routes via mDNS so hosting applications in an mDNS aware LAN is a breeze. THIS IS COMPLETELY UNSUPPORTED. DON’T EVEN THINK OF RED HAT SUPPORT WHEN YOU […]
In May this year, my colleague Götz Rieger came across a poster in Berlin which piqued our interest: Open source bread? Free (libre) seeds? What is this all about? With German Thanksgiving on Oct. 2nd we want to take the opportunity to learn more about this initiative. To this end, we conducted an email interview […]
OpenShift 3.3 and later contain the functionality to route pod traffic to the external world via a well-defined IP address. This is useful for example if your external services are protected using a firewall and you do not want to open the firewall to all cluster nodes. The way it works is that a egress […]
In the OpenShift world, Services take place on the OSI Layer 3 / IP, while Routing is an OSI Layer 7 / HTTP/TLS concept. Once you’ve wrapped your head around this backwards choice of naming, things are fairly easy: An OpenShift Router is a component which listens on a physical host’s HTTP/S ports for incoming […]
To allow stable endpoints in an environment of ever changing starting and stopping Pods (and therefore constantly changing IP addresses), Kubernetes introduces (and OpenShift uses) the concept of services. Services are stable IP addresses (taken per default from the 172.30.0.0/16 subnet) that remain the same as long as the service exists. Connection requests to a […]
So far, this sounds like a lot of effort to achieve a little more than a plain docker host – containers that can talk to each other and to the host network, potentially segregated based on kubernetes namespace. However OpenShift SDN also allows pods on different nodes to communicate with each other. To this end, […]
In OpenShift, networking is equally simple from a container point of view. Within the container’s namespace there is a eth0 network interface configured and services such as DNS just work. You can still use dedicated NICs on the host to isolate specific types of traffic. What’s the difference? It turns out there is hardly any […]
From a container point of view, networking on a plain Docker Host is simple. A running container is nothing more than a Linux process which is namespaced and constrained with regards to access (SELinux) and resource consumption (cgroups). In each namespace, there is a single (virtual) network interface called eth0 which is assigned an IP […]
If you are debugging IPTables, it is handy to be able to trace the packets while it traverses the various chains. I was trying to find out why port forwarding from the external NIC to a virtual machine attached to a virtual bridge device was not working. You need to perform the following preparations: Load […]