Regular readers will know that I have been spending quite a bit of time recently looking at Kubernetes running on vSphere. I’ve written a number of posts on the storage side of things, which you can read here as part of my 101 series. I also posted about how you can setup vRealize Operations Manager 7.5 and add the Management Pack for Container Monitoring. This provide some really good dashboards for examining the state of your K8s clusters, as well as detailed breakdowns into K8s node VM health and performance (CPU, Memory, DIsk IO). Not only that, but you can…
This will be last article in the 101 series, as I think I have covered off most of the introductory storage related items at this point. One object that came up time and again during the series was services. While not specifically a storage item, it is a fundamental building block of Kubernetes applications. In the 101 series, we came across a “headless” service with the Cassandra StatefulSet demo. This was where service type ClusterIP was set to None. When we started to look at ReadWriteMany volumes, we used NFS to demonstrate these volumes in action. In the first NFS…
In my most recent 101 post on ReadWriteMany volumes, I shared an example whereby we created an NFS server in a Pod which automatically exported a File Share. We then mounted the File Share to multiple NFS client Pods deployed in the same namespace. We saw how multiple Pods were able to write to the same ReadWriteMany volume, which was the purpose of the exercise. I received a few questions on the back on that post relating to the use of Services. In particular, could an external NFS client, even one outside of the K8s cluster, access a volume from…
The vROps Management Pack for Container Monitoring is something that I had been meaning to install and configure for a while now, but I just haven’t had a chance until very recently. If you didn’t know. VMware’s vRealize Operations has a Management Pack for Container Monitoring. This includes adapters for both the Pivotal Container Service (PKS) as well as Kubernetes. In my environment I had already deployed PKS which I was then using for deploying my Kubernetes clusters. I found the official documentation a little light on what exact information was required for both the PKS Adapter and the Kubernetes…
Over the last number of posts, we have spent a lot of time looking at persistent volumes (PVs) instantiated on some vSphere back-end block storage. These PVs were always ReadWriteOnce, meaning they could only be accessed by a single Pod at any one time. In this post, we will take a look at how to create a ReadWriteMany volume, based on an NFS share, which can be accessed by multiple Pods. To begin, we will use an NFS server image running in a Pod, and show how to mount the exported file share to another Pod, simply to get the…
We have looked at quite a few scenarios when Kubernetes is running on vSphere, and what that means for storage. We looked at PVs, PVC, PODs, Storage Classes, Deployments and ReplicaSets, and most recently we looked at StatefulSets. In a few of the posts we looked at some controlled failures, for example, when we deleted a Pod from a Deployment or from a StatefulSet. In this post, I wanted to look a bit closer at an uncontrolled failure, say when a node crashes. However, before getting into this in too much details, it is worth highlighting a few of the…
In my last post we looked at creating a highly available application that used multiple Pods in Kubernetes with Deployments and ReplicaSets. However, this was only focused on Pods. In this post, we will look at another way of creating highly available applications through the use of StatefulSets. The first question you will probably have is what is the difference between a Deployment (with ReplicaSets) and a StatefulSet. From a high level perspective, conceptually we can consider that the major difference is that a Deployment is involved in maintaining the desired number of Pods available for an application, whereas a…