Kubernetes operator demo

Table of Contents

• About
• Quickstart
• Improvements
• Notes
• How it's made

About

A custom controller written in Go, which extends the Kubernetes CRDs and control's the deployments of a given app.

Note: This code based on the kubebuilder template.

Quickstart

In order to build the controller/manager, it's recommended to use the make command

$ make
$ make install

This should also automatically apply the custom CRD resources to Kubernetes. You can do this manually by:

kubectl apply -f config/crd/bases/apps.kubeoperator.local_apps.yaml

Start the controller / manager

In order to run the application, simple use the command below, which will generate the necessary manifests and then uses the built-in go run command (go run cmd/main.go)

make run

Configuration for the sample nginx app:

kubectl apply -f config/samples/custom_v1_app.yaml

Verify the pods / progress

kubectl get app -n <namespace>
kubectl get deployments -n <namespace>
kubectl get pods -n <namespace>
kubectl get svc -n <namespace>
kubectl get hpa -n <namespace>

Improvements

• Ingress controller / Let's encrypt Haven't really found a solution which synergies well with the current kubebuilder template without using Helm
• Secrets management: By using Mozilla Sops and Age we should be able to generate secrets in a safer way. Sops supports a lot of encryption methods like: HasiCorp's Vault, GCP KMS, PGP, etc.; but Age is the most promising one in my opinion.

Notes

Let's talk about the elephant in the room (picture); In 2023 still many dev tools are not platform-agnostic or simply behave differently on different OS.

• How some part of a make file still refuses the work properly
• or how the exact same code works perfectly one way [from Win or WSL] then later from the other terminal it causes the pods to stuck in CrashLoop. Not sure if the 2 environment fighting with each-other for the permissions, but often I had to delete the kind/minikube clusters to reset the strange behavior.

Docker registry images can be found at: https://gitlab.com/ftamas88/kubernetes-operator-demo/container_registry