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Kubernetes 1.24: Bye Bye Docker
Since I just got extra 4 CPU cores and 32GB of memory to my garage Kubernetes lab cluster, there’s enough capacity to let me juggle some upgrades. My cluster was running Kubernetes version 1.22 for almost a year which is already reaching end-of-life in many commercial managed Kubernetes offerings. After some reading I found that…
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A Load Balancer for Cloud SQL Replicas
TL;DR: As of Aug 2022, there’s no out of box load balancing for Google Cloud SQL read replicas. So I built one for MySQL replicas with HAProxy with the ability to dynamically reload when number of replicas has changed. It will be quite straight forward to run a few HAProxy pods in Kubernetes as a…
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How to Use a Local Persistent Volume
TL;DR: A local persistent volume in a Kubernetes cluster is a persistent volume allocated in a certain node. Any pod mounting the volume will be automatically scheduled in the same node. Since it’s limited to 1 node, clearly it can’t be used as a high-availability solution, but hey, it’s quite Ok to use it for…
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How To Renew Certificates in Kubernetes Clusters, Revisited
There is a lot of TLS certificates used by the core of a Kubernetes cluster and a popular one is the client-server pair used by kubectl to authenticate to the cluster control plane. In my previous notes on how to renew certificates in a Kubernetes cluster with kubeadm, I found that the steps are quite…
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Blog Deployed With Jsonnet, Grafana Tanka and ArgoCD
It’s been a year since I did the ‘Hello World’ with Jsonnet and Tanka, then I made a simple side-loader container to install Tanka as a plugin to ArgoCD and finally deployed an httpbin container with ArgoCD + Tanka + Jsonnet. However since Jsonnet wasn’t used in my work, those things were shelved afterwards. Recently…
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Easy Kubernetes Secret Integration with ExternalSecrets
In a Kubernetes cluster, A Kubernetes Secret is a resource type to hold sensitive data for the apps to use, such as an API key or database password. Secrets are namespaced so if I have RBAC access to a namespace, I can pretty much see all the secrets there, as the secrets are only base64…
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Better Resilience for Kubernetes Pods
I happened to notice that all 3 pods serving this blog in my Kubernetes cluster were allocated to a same node. I thought Kubernetes will try its best to shuffle pods of a deployment into different nodes by default but guess I expected too much. Note the knode3 below Have you spotted the problem? In…
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How to Regulate Egress Access in Kubernetes with Istio
Usually I don’t mind to give pods unlimited egress access, ie. the pods I deployed can access the whole internet if it needs to. However when the pods take input from users it’s a whole different story. For example, running some sandbox applications such as an online Python learning environment, the workload can be abused…