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Rebuild a Kubernetes Node Without Downtime
When I built the in-house Kubernetes cluster with Raspberry PIs, I followed the kubeadm instructions and installed Raspberry PI OS on the PIs. It was all good except the RPI OS is 32-bit. Now I want to install a Ubuntu 20.04 Server ARM64 on this PI, below are steps with which I rebuilt the node…
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OpenSSL Commands to Verify TLS Certs in Kubernetes Secrets
Sometimes a TLS cert deployed into a Kubernetes cluster in a Secret doesn’t work as expected. Here are some handy commands to verify the certs. The sample commands work for Istio Ingressgateway, but should be adapted to other CNIs without huge efforts. Commands to verify the cert served by your web-app Commands to verify the…
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Fixed: Duplicated Cluster IPs in a Kubernetes Cluster
A Cluster IP is an IP address allocated in the cluster’s virtual LAN, usually allocated to Kubernetes Services. As a user nobody should care about which cluster IP a service would get because we will use the service-name.namespace-name DNS name which will map to that IP automatically. In my case, some services in a GKE…
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The Upgrade of Kubernetes Ingress Nginx
The ingress-nginx container image I’ve been using was v0.25, and that’s more than 1 year old. The recent release is v0.44 but it’s a big leap from 25 to 44 and I’ve found some major differences between the 2 versions. Version 0.25 implemented API version of networking.k8s.io/v1beta1 while version 0.44 has networking.k8s.io/v1. Here are samples…
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Kubernetes: How to Use Affinity
Affinity is a great feature in Kubernetes to assign pods to nodes based on labels. In my case, I have a hybrid Kubernetes cluster with half nodes are of X86 architecture and other half of ARM architecture, and I need to deploy the X86 only containers to the X86 nodes. Of course I can build…
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Kubernetes and GitOps with Flux CD V2.0
GitOps could be the next big thing in cloud automation so I’d give it a try with my in house hybrid Kubernetes cluster. I was recommended to try Flux CD and there’s a good reference project initiated by my colleage: k8s-gitops. However, in order to fully understand how to use Flux CD, I chose to…
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Renew Certificates Used in Kubeadm Kubernetes Cluster
It’s been more than a year since I built my Kubernetes cluster with some Raspberry PIs. There was a few times that I need to power down everything to let electricians do their work and the cluster came back online and seemed to be Ok afterwards, given that I didn’t shutdown the PIs properly at…