label-controller

Trivial Kubernetes controller for adding Pod labels.

Controller development

Controller in Go will add a pod-name label to pods that have a specific annotation.

• Use Operator SDK and scaffold the repo as if developing Operator. Opeartor will contain a single controller. operator-sdk init --domain=jkosik --repo=github.com/jkosik/k8s-label-controller

main.go was created. Note: when developing Helm-based Operator, no Go files were created.

• We will also not need any CRDs since, Controller will handle existing resource - Pod. Initialize Controller code: operator-sdk create api --group=core --version=v1 --kind=Pod --controller=true --resource=false creates controllers/pod_controller.go

We now have a new file: controllers/pod_controller.go. This file contains a PodReconciler type with two methods:

• Method Reconcile implements our logic.
• Method SetupWithManager called when Operator starts and executes reconciliation.

Details documented here: https://kubernetes.io/blog/2021/06/21/writing-a-controller-for-pod-labels/.

WIP...to be finished...