Kubernetes

If you’re struggling to deploy Kubernetes (k8s) clusters, you’re not alone. There are a bunch of different ways to deploy Kubernetes and there are different settings depending on what cloud provider you’re using. This post will focus on installing Kubernetes on vSphere with Kubeadm. At the end of this post, you should have what you need to manually deploy k8s in a vSphere environment on ubuntu. Prerequisites NOTE: This tutorial uses the “in-tree” cloud provider for vSphere. This is not the preferred method for deployment going forward. More details can be found here for reference. ...

Sometimes we need to run a container to do a specific task, and when its completed, we want it to quit. Many containers are deployed and continuously run, such as a web server. But other times we want to accomplish a single task and then quit. This is where a Job is a good choice. Jobs and CronJobs - The Theory Perhaps, we need to run a batch process on demand. Maybe we built an automation routine for something and want to kick it off through the use of a container. We can do this by submitting a job to the Kubernetes API. Kubernetes will run the job to completion and then quit. ...

Securing and hardening our Kubernetes clusters is a must do activity. We need to remember that containers are still just processes running on the host machines. Sometimes these processes can get more privileges on the Kubernetes node than they should, if you don’t properly setup some pod security. This post explains how this could be done for your own clusters. Pod Security Policies - The Theory Pod Security policies are designed to limit what can be run on a Kubernetes cluster. Typical things that you might want to limit are: pods that have privileged access, pods with access to the host network, and pods that have access to the host processes just to name a few. Remember that a container isn’t as isolated as a VM so we should take care to ensure our containers aren’t adversely affecting our nodes’s health and security. ...

In the traditional server world, we’ve taken great lengths to ensure that we can micro-segment our servers instead of relying on a few select firewalls at strategically defined chokepoints. What do we do in the container world though? This is where network policies come into play. Network Policies - The Theory In a default deployment of a Kubernetes cluster, all of the pods deployed on the nodes can communicate with each other. Some security folks might not like to hear that, but never fear, we have ways to limit the communications between pods and they’re called network policies. ...

If you’ve just gotten started with Kubernetes, you might be curious to know how the desired state is achieved? Think about it, you pass a YAML file to the API server and magically stuff happens. Not only that, but when disaster strikes (e.g. pod crashes) Kubernetes also makes it right again so that it matches the desired state. The mechanism that allows for Kubernetes to enforce this desired state is the control loop. The basics of this are pretty simple. A control loop can be though of in three stages. ...

DaemonSets can be a really useful tool for managing the health and operation of the pods within a Kubernetes cluster. In this post we’ll explore a use case for a DaemonSet, why we need them, and an example in the lab. DaemonSets - The Theory DaemonSets are actually pretty easy to explain. A DaemonSet is a Kubernetes construct that ensures a pod is running on every node (where eligible) in a cluster. This means that if we were to create a DaemonSet on our six node cluster (3 master, 3 workers), the DaemonSet would schedule the defined pods on each of the nodes for a total of six pods. Now, this assumes there are either no taints on the nodes, or there are tolerations on the DaemonSets. ...

One of the best things about Kubernetes, is that I don’t have to think about which piece of hardware my container will run on when I deploy it. The Kubernetes scheduler can make that decision for me. This is great until I actually DO care about what node my container runs on. This post will examine one solution to pod placement, through taints and tolerations. Taints - The Theory Suppose we had a Kubernetes cluster where we didn’t want any pods to run on a specific node. You might need to do this for a variety of reasons, such as: ...

The Kubernetes series has now ventured into some non-native k8s discussions. Helm is a relatively common tool used in the industry and it makes sense to talk about why that is. This post covers the basics of Helm so we can make our own evaluations about its use in our Kubernetes environment. Helm - The Theory So what is Helm? In the most simplest terms its a package manager for Kubernetes. Think of Helm this way, Helm is to Kubernetes as yum/apt is to Linux. Yeah, sounds pretty neat now doesn’t it? ...

The focus of this post is on pod based backups, but this could also go for Deployments, replica sets, etc. This is not a post about how to backup your Kubernetes cluster including things like etcd, but rather the resources that have been deployed on the cluster. Pods have been used as an example to walk through how we can take backups of our applications once deployed in a Kubernetes cluster. ...

As with all systems, we need to be able to secure a Kubernetes cluster so that everyone doesn’t have administrator privileges on it. I know this is a serious drag because no one wants to deal with a permission denied error when we try to get some work done, but permissions are important to ensure the safety of the system. Especially when you have multiple groups accessing the same resources. We might need a way to keep those groups from stepping on each other’s work, and we can do that through role based access controls. ...