Category: Opensource

  • 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 […]

  • How to Share Files on Linux Using Docker

    Prerequisites: A Linux computer(mine is Fedora 36) Docker(or podman) installed I know, there’s traditional ways to share files over network such as samba or the very current cloud way such as Google Drive. Or I can just use a USB key. But I managed to impress my child(who has to use Windows because of her […]

  • 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 […]

  • 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 […]

  • Easy Kubernetes Secret Integration with ExternalSecrets

    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 […]

  • Installation of Fedora 36 on Dell XPS 13 9380

    Installation of Fedora 36 on Dell XPS 13 9380

    I happened to have acquired a used Dell XPS 13 9380, which is a nice little ultrabook with Intel 8th gen i7 CPU, 16GB memory(not upgrade-able), 512GB nvme SSD and a beautiful 13″ 4k screen. It has Windows 10 installed. Of course I have no intention to continue to use the stock Windows 10. At […]

  • 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 […]

  • 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 […]