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Quick Tip - Preserving FQDN hostname on Photon OS

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Over the weekend, I was troubleshooting an issue that was reported by one of our VMware Event Broker Appliance (VEBA) users who was helping with testing one of our upcoming features. The user found that after rebooting the VEBA appliance, the Antrea interfaces were no longer being re-created and pod networking seems to have been broken.

We initially thought it was related to switching to the latest Photon OS version or updating to the latest Antrea CNI release, since everything else was pretty much the same. Even after reverting both versions back to what we initially had, the reboot issue continued to persist. What was even more strange was that the current shipping version of the VEBA (v0.6.1) OVA was not experiencing this issue and had no problems with an OS reboot, which is something I have done many times.

The only logical conclusion that I could come up with to explain this problem is that a behavior change must have occurred within Photon OS from the time we built the previous appliance to what we are seeing now. While troubleshooting Antrea, it was pointed out that Kubernetes (K8s) node is probably unhealth and if so, I may want to look at the kubelet logs to see if it provided any hints. I initially did not both looking at the K8s layer, thinking this was related to change in Antrea since it handled pod networking. Looking at the kubelet logs, I found a ton of entries with the following:

396 kubelet.go:2243] node "veba" not found

I thought this was a bit strange, especially as our appliance has its hostname configurred with a Fully Qualified Domain Name (FQDN) which is veba.primp-industries.local and we had proper entries in both /etc/hostname and /etc/hosts.

Sure enough, when I ran hostname, they all returned the short hostname instead of the FQDN (which it returned properly prior to the reboot)

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Quick Tip - Setting up Kubernetes using Containerd on Photon OS

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As part of the VMware Event Broker Appliance (VEBA) project, I was recently evaluating a newer version of Kubernetes (v1.21.3) and also switching the container runtime from Docker to Containerd. I figured this probably should not be that difficult, especially since we are already use Containerd within Tanzu Kubernetes Grid (TKG) which is our commercial Kubernetes (k8s) offering and that base OS is VMware Photon OS. How hard could this be, right!? (famous last words) 😂

We use kubeadm to setup K8s and read in a very basic configuration file and after following the official K8s instructions for prepping the environment to use containerd, I was surprised when I ran into the following error:

Unfortunately, an error has occurred:
timed out waiting for the condition

This error is likely caused by:
- The kubelet is not running
- The kubelet is unhealthy due to a misconfiguration of the node in some way (required cgroups disabled)

If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
- 'systemctl status kubelet'
- 'journalctl -xeu kubelet'

Additionally, a control plane component may have crashed or exited when started by the container runtime.
To troubleshoot, list all containers using your preferred container runtimes CLI.

Here is one example how you may list all Kubernetes containers running in cri-o/containerd using crictl:
- 'crictl --runtime-endpoint /run/containerd/containerd.sock ps -a | grep kube | grep -v pause'
Once you have found the failing container, you can inspect its logs with:
- 'crictl --runtime-endpoint /run/containerd/containerd.sock logs CONTAINERID'

error execution phase wait-control-plane: couldn't initialize a Kubernetes cluster
To see the stack trace of this error execute with --v=5 or higher

Unfortunately, this lead me down a huge rat hole of troubleshooting and trying various configurations and suggestions from the Internet. Ultimately, none of the suggested solutions solved my problem. After exhausting all my options and spending more time that I would like to admit, I decided to ask in the Kubernetes Slack community to see if anyone might have an idea. There were not any specific suggestions that helped me understand the issue further but there was a question about how Containerd came to be on the system and that gave me one more thing to try.

Both Photon OS 3.0 and 4.0 ships with Containerd and after installing the desired kubeadm, kubectl and kubelet, I had wrongfully assumed that the version of Containerd would simply work.

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Exploration of Tanzu Kubernetes Grid (TKG) multi-vCenter Server templating using YTT

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The motivation behind this blog post originates from a really cool blog post by Mike Brown who shared an interesting Telco use case for wanting to running Tanzu Kubernetes Grid (TKG) on VMware Cloud on AWS (VMConAWS) and centrally managing TKG Workload Clusters, which would run at each individual Edge/Cell Site location.

While reading through Mike's blog post, I noticed one of the steps was to edit the generated YAML from the TKG Management Cluster which would then be used to deploy the individual TKG Workload Clusters. This would need to happen for each new deployment 😮 and of course, this could be very error prone and frustrating for end users. Here is an example of what the YAML file looks like which is over 1K+ lines!

This screams for automation and I had been looking for a reason to try out YTT again, which is a YAML templating tool that is part of the open source project Carvel. Although I had played with YTT before, it did not feel intuitive, especially for a new user who was trying to solve a quick problem. I figured this was my opportunity to take another look at YTT.

After a couple of hours and a lot of trial/error, I ended up with a partial solution and realized that I would not be able to figure this out given there were even more complicated sections within the YAML. I felt the bar to getting started with YTT was still too high and it may not be the right tool for this particular situation. I opted for a quicker solution using sed, which I had experience with before, but I also know that depending on the problem, sed can be just as complex and I also dislike regular expressions  🙂

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