Kubernetes

A pretty common task that a Kubernetes administrator must do is to resize the cluster. We need more nodes to handle more workloads, or we’ve overprovisioned a cluster and are trying to save costs. This usually took some custom automation scripts such as node autoscaler, or it was done manually based on request. Tanzu Mission Control can resize our cluster very simply from the TMC portal. Scale Out a Cluster Within the TMC Portal, find the cluster that needs to be resized. Within the cluster screen, find the “Node pools” menu. Node pools define the worker nodes that are part of the Kubernetes cluster thats been deployed. ...

Most of the blog posts I write about Kubernetes have examples using publicly available images from public image registries like DockerHub or Google Container Registry. But in the real world, companies use private registries for storing their container images. There are a list of reasons why you might want to do this including: Custom code is inside the container such as business logic or other intellectual property. On-premises private repos provide solutions to bandwidth or firewall restrictions. Custom scanning software is being integrated for vulnerability management. In this post, we’ll setup our Kubernetes cluster to be able to use a private container registry. ...

Recently I was tasked with setting up some virtual machines to be used as a load balancer for a Kubernetes cluster. The environment we were deploying our Kubernetes cluster didn’t have a load balancer available, so we thought we’d just throw some envoy proxies on some VMs to do the job. This post will show you how the following tasks were completed: Deploy Envoy on a pair of CentOS7 virtual machines. Configure Envoy with health checks for the Kubernetes Control Plane Install keepalived on both servers to manage failover. Configure keepalived to failover if a server goes offline, or the envoy service is not started. Deploy Envoy The first step will be to setup a pair of CentOS 7 servers. I’ve used virtual servers for this post, but baremetal would work the same. Also, similar steps could be used if you prefer debian as your linux flavor. ...

If you’ve been on the operations side of the IT house, you know that one of your primary job functions is to ensure High Availability (HA) of production workloads. This blog post focuses on making sure applications deployed on a vSphere Kubernetes cluster will be highly available. The Control Plane Ok, before we talk about workloads, we should discuss the Kubernetes Control plane components. When we deploy Kubernetes on virtual machines, we have to make sure that the brains of the Kubernetes cluster will continue working even if there is a hardware failure. The first step is to make sure that your control plane components are deployed on different physical (ESXi) hosts. This can be done with a vSphere Host Affinity Rule to keep k8s VMs pinned to groups of hosts or anti-affinity rules to make sure two control plane nodes aren’t placed on the same host. After this is done, your Load Balancer should be configured to point to your k8s control plane VMs and a health check is configured for the /healthz path. ...

You’ve stood up your Kubernetes (k8s) cluster and are really looking forward to all of your coworkers deploying containers on it. How will you get everyone logged in? Creating local service accounts and distributing KUBECONFIG files (securely), seems like a real chore. This post will show how you can use Active Directory authentication for Kubernetes Clusters. This post will use two projects, dex and gangway, to perform the authentication against ldap and return the Kubernetes login information to the user’s browser. The end result will look something like the screen below. The authenticated user will receive instructions on installing the client and setting up certificates for authentication. ...

The way you deploy Kubernetes (k8s) on AWS will be similar to how it was done in a previous post on vSphere. You still setup nodes, you still deploy kubeadm, and kubectl but there are a few differences when you change your cloud provider. For instance on AWS we can use the LoadBalancer resource against the k8s API and have AWS provision an elastic load balancer for us. These features take a few extra tweaks in AWS. ...

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. ...

One of my least favorite parts of computers is dealing with certificate creation. In fact, ya know those tweets about what you’d tweet if you were kidnapped and didn’t want to tip off the kidnapers? Yeah, I’d tweet about how I love working with certificates. They are just not a fun thing for me. So when I found a new project where I needed certificates created, I was not really excited. ...

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. ...