First step to write kubernetes operator without using operator-sdk or kubebuilder.
first build the docker image
docker build -t webui-controller .
then load image to minikube
minikube image load webui-controller
create the CRD
kubectl apply -f yaml/crd.yaml
then deploy the controller
kubectl apply -f yaml/deploy-controller.yaml
and finally deploy the example
kubectl apply -f yaml/example.yaml