I set up a few Kubernetes clusters preparing for the CKA exam and discovered that upon reboot, my control plane node didn’t work. Running any kubectl command I get:
The connection to the server 192.168.1.57:6443 was refused - did you specify the right host or port?
This is a common error message that can result from numerous issues but I started troubleshooting by seeing if the kubelet process was running with ps aux | grep kube. Nothing…no kubelet service running. Then I looked at /var/log/syslog and I found the problem — swap was back on!
In Part 1, we created the Kubernetes cluster by running kubeadm init on the control plane node. In part 2 we’ll add a node to an existing cluster that will be capable of running pods which is apparently a possible CKA exam scenario (see cluster ik8s):
The new CKA 2020 for Kubernetes v1.19 blueprint has an objective to, “Use Kubeadm to install a basic cluster.” While I haven’t taken the CKA v1.19 exam yet, based on the exam environment from Linux Foundation (image below), it doesn’t appear that creating a brand new cluster will be necessary in the exam. Instead, cluster ik8s is missing a node and I assume the task will involve gathering the information to add the node to the cluster.
While I’m not an advanced Linux user, I’m comfortable navigating a Linux filesystem. But the lack of a GUI always gave me a bit of anxiety when trying to find where a binary or config file lives. To amplify that frustration, while preparing for the CKA 1.19 exam, I realized that Kubernetes doesn’t store things in one directory so to help myself visualize and remember the directories better, I made the below graphic that illustrates the directories that are necessary for troubleshooting a Kubernetes cluster. In this post, we’ll explore how Kubernetes uses each directory and it’s importance for the CKA.
In Part 1, we built the hardware build of materials and determined the utilization of a basic VMware Cloud Foundation (VCF) management domain deployment. But we need to put the “cloud” in by adding automation and self-service capabilities provided by vRealize Suite. To accomplish that, we can use SDDC Manager to deploy all the components of the vRealize Suite: Operations, Automation, and Log Insight into the SDDC. In this post, we’ll explore the compute and storage requirements for these components like we did in the previous post. This is going to explore the components required for a single region SDDC. There are a few more steps and components needed for setting up Cross-Region support.
When talking with customers about deploying a standard VMware Cloud Foundation (VCF) architecture, the topic of the hardware requirements and details for the management domain are usually glossed over. There’s a basic understanding that it will consist of 4 hosts with sufficient resources to run the SDDC components for the workload domains that it manages. When it comes time for purchasing though, what is the actual hardware that will run the management domain and does VMware have recommended specs for hardware for the management domain?
The final module of the Cluster Architecture, Installation, and Configuration is Implement etcd backup and restore. Let’s quickly perform the actions we need to complete this step for the exam.
Perform a Backup of etcd
While it’s still early and details of the CKA v1.19 environment aren’t known yet, I’m anticipating a small change to how etcd backup and restore is performed. If you’ve been preparing for the CKA before the September 2020 change to Kubernetes v1.19, you may know be familiar with the environment variable export ETCDCTL_API=3 to ensure you’re using version 3 of etcd’s API, which has the backup and restore capability. However, Kubernetes v1.19 ships with etcd 3.4.9 and in etcd 3.4.x, the default API version is 3 so this process is no longer necessary! If etcdctl version returns a version lower than 3.4.x, you will still need to set the API version to 3 for performing backup and restore operations.
Amazon Smart Plugs are an excellent addition to automate your home with Alexa. However, if you’re an advanced home automation user using a more robust solution like Home Assistant, you will find their limited usage to the Alexa app very frustrating!
I discovered a solution to get Amazon Smart Plugs accessible in Home Assistant using input booleans and template binary sensors. By pairing a binary sensor from Home Assistant with an Amazon Smart Plug inside of an Alexa Routine, we’re able to control the smart plug from Home Assistant!
As part of my goal to obtain the Certified Kubernetes Administrator (CKA) certification, I went through the Kubernetes documentation to find the specific links that map to the domain knowledge objectives for the v1.19 exam.
I’ve been slowly working towards CKA and there is a significant change to the curriculum with the recent announcement from the Cloud Native Computing Foundation (CNCF) that the Certified Kubernetes Administrator (CKA) exam curriculum will be updated in September 2020 to cover Kubernetes v1.19. The v1.19 curriculum is a huge change from the v1.18 curriculum I’ve been studying and I prepared this comparison to help with my studies and hope it provides some clarity to those in a similar situation as me.
Kubernetes v1.19 hasn’t been finalized yet but there will certainly be new features, added commands, and others deprecated as part of the update. But that’s not the only change — the exam curriculum is also changing a lot!