Create a kubebuilder project, which requires an empty folder

kubebuilder init --domain opsblogs.cn

Check project layout

cat PROJECT

domain: opsblogs.cn
layout:
- go.kubebuilder.io/v3
projectName: demo-operator
repo: github.com/noonme/demo-operator
version: "3"

Create API, create resource[Y], create controller[Y]

kubebuilder create api --group apps --version v1beta1 --kind MyDaemonset

Open project with IDE and edit api/v1alpha1/simplestatefulset_types.go

// MyDaemonsetSpec defines the desired state of MyDaemonset
type MyDaemonsetSpec struct {
	// INSERT ADDITIONAL SPEC FIELDS - desired state of cluster
	// Important: Run "make" to regenerate code after modifying this file

	// Foo is an example field of MyDaemonset. Edit mydaemonset_types.go to remove/update
	Image string `json:"image,omitempty"`
}

// MyDaemonsetStatus defines the observed state of MyDaemonset
type MyDaemonsetStatus struct {
	AvaiableReplicas int `json:"avaiableReplicas,omitempty"`
	// INSERT ADDITIONAL STATUS FIELD - define observed state of cluster
	// Important: Run "make" to regenerate code after modifying this file
}

Check Makefile

Build targets:
    ### create code skeletion
    manifests: generate crd
    generate: generate api functions, like deepCopy

    ### generate crd and install
    run: Run a controller from your host.
    install: Install CRDs into the K8s cluster specified in ~/.kube/config.

    ### docker build and deploy
    docker-build: Build docker image with the manager.
    docker-push: Push docker image with the manager.
    deploy: Deploy controller to the K8s cluster specified in ~/.kube/config.

Edit controllers/mydaemonset_controller.go, add permissions to the controller

//+kubebuilder:rbac:groups=apps.cncamp.io,resources=mydaemonsets/finalizers,verbs=update
// Add the following
//+kubebuilder:rbac:groups=core,resources=nodes,verbs=get;list;watch
//+kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;watch;create;update;patch;delete

Generate crd

make manifests

Enable webhooks

Install cert-manager

kubectl apply -f https://github.com/jetstack/cert-manager/releases/download/v1.6.1/cert-manager.yaml

Create webhooks

kubebuilder create webhook --group apps --version v1beta1 --kind MyDaemonset --defaulting --programmatic-validation

Change code

Enable webhook in config/default/kustomization.yaml

Redeploy

Build & install

make build
make docker-build
make docker-push
kubectl create -f demo-operator/config/samples/roleAdd/*
make deploy