How to re-ip your Kubernetes Cluster

Recently we’ve undergone some massive networking changes within a lab I frequently use – the kind which involves re-iping nearly everything within the entire lab! For the most part, we’ve been pretty successful and the process has been fairly straightforward. That said, Kubernetes is still somewhat new to me, and re-iping both the controller and worker nodes is a little bit more involved than simply changing the netplan config on Ubuntu! So with that, let’s take a look at how to re-ip a Kubernetes Cluster.

Speaking of netplan – that’s step 1

This part is pretty straightforward and simply involves changing the IP of the underlying operating system itlsef – in my case, Ubuntu. Simply navigate to /etc/netplan and modify the file within that directory that contains your IP configuration – in my case, it meant changing it to something similar to below

Once it is saved apply it with

With that out of the way we can now get into the nitty-gritty of reconfiguring Kubernetes to see this new IP

And now, let’s start to re-ip the Kubernetes Cluster

If you go ahead and run some kubectl commands you’ll quickly realize that things are still looking at your old IP address – and simply changing your .kube/config file here to point to the new IP address won’t help things as the internal workings of Kubernetes is still pointing to that old address as well for services like the API server. There is a lot of information out there around how to reconfigure all of this, and I followed quite a few guides and found the below way to be the easiest and, well, let’s face it, even better, the least amount of work…

First, head to your controller (master) node and run the following