Disrupting OpenShift — Part 2

Introduction

In my last blog, I talked about what happen when I destroy the master Machines CR in an OpenShift 4.1 cluster (https://medium.com/@epatro/disrupting-openshift-part-1-2ba73ef8b46c).

In my experiment, OpenShift didn’t create a new master, as there is no MachineSet associated with the master Machines.

In this blog, I will talk how to recreate an OpenShift master. It’s pretty simple.

Rebuilding a master

My environment is in danger, as I am running with just 2 masters, and if anything happens with one master, OpenShift would simply halt (until most masters are available).

So, let’s rebuild the third master. Again, I follow the concept of Machine CR to create the VM.

First, I need the definition of a Machine CR that I can use to create a new one. So, I run the following commands to create the YAML file:

So now I have a YAML file with the master-1 definition, which I can modify to create the master-0. I just changed metadata.name and ran the following command:

oc create -f master1.yaml

Then I can confirm the machine master-0 has been created:

After a few minutes, I can confirm OpenShift has created a new master:

Voilà: environment restored, with 3 master nodes.

Conclusion

The use of the Machine CR makes very simple to add infrastructure (VMs) to an OpenShift environment.

In this article, I showed how a master node can be created when one is accidentally (or intentionally) destroyed.

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