Demo Add The Service Builder

The web app controller already creates a Deployment and a ConfigMap. The final child we need is a Service, which gives the pods a stable cluster-internal DNS name and a single network entry point for other components to reach the WebApp. In this lesson we will:

Add a helper named serviceFor that builds a *corev1.Service for a given WebApp.
Wire that helper into the reconciler so the controller creates a Service when it does not exist.

Below are the authoritative code examples and the reconcile pattern used by the controller. Why this matters: A Kubernetes Service provides stable networking for a set of pods selected by labels. A controller must construct the desired Service, attach an owner reference (so child resources are garbage-collected when the parent is removed), check if the Service already exists, and create it if the API returns NotFound. This is the same pattern used for ConfigMaps and Deployments. Context — existing ConfigMap helper

func configMapFor(w *webappv1.WebApp) *corev1.ConfigMap {
	return &corev1.ConfigMap{
		ObjectMeta: metav1.ObjectMeta{
			Name:      w.Name + "-config",
			Namespace: w.Namespace,
			Labels:    map[string]string{"app": w.Name},
		},
		Data: map[string]string{
			"welcome.html": "<h1>Hello from " + w.Name + "</h1>",
		},
	}
}

Add the Service helper

Use the same app label as the other children so the Service can select the same pods.
Set Service Type to ClusterIP.
Expose port 80 and route it to container port 80 with TCP.

func serviceFor(w *webappv1.WebApp) *corev1.Service {
	labels := map[string]string{"app": w.Name}
	return &corev1.Service{
		ObjectMeta: metav1.ObjectMeta{
			Name:      w.Name,
			Namespace: w.Namespace,
			Labels:    labels,
		},
		Spec: corev1.ServiceSpec{
			Type:     corev1.ServiceTypeClusterIP,
			Selector: labels,
			Ports: []corev1.ServicePort{
				{
					Port:       80,
					TargetPort: intstr.FromInt(80),
					Protocol:   corev1.ProtocolTCP,
				},
			},
		},
	}
}

The Service selector must exactly match the labels applied to the Deployment’s Pod template. If these labels differ, the Service will be present but will not route traffic to any pods.

Wire the Service creation into Reconcile Follow the same reconcile pattern used for the ConfigMap and Deployment:

Build the desired object (serviceFor).
Attach a controller owner reference with controllerutil.SetControllerReference.
Attempt to Get the object.
If Get returns apierrors.IsNotFound, Create the object.
Handle other errors appropriately.

Complete reconcile snippet (reads the WebApp, ensures ConfigMap and Service exist):

func (r *WebAppReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	var webapp webappv1.WebApp
	if err := r.Get(ctx, req.NamespacedName, &webapp); err != nil {
		if apierrors.IsNotFound(err) {
			// Resource not found; it might have been deleted after the reconcile request.
			return ctrl.Result{}, nil
		}
		return ctrl.Result{}, err
	}

	// Ensure ConfigMap
	desiredCM := configMapFor(&webapp)
	if err := controllerutil.SetControllerReference(&webapp, desiredCM, r.Scheme); err != nil {
		return ctrl.Result{}, err
	}

	foundCM := &corev1.ConfigMap{}
	err := r.Get(ctx, types.NamespacedName{Name: desiredCM.Name, Namespace: desiredCM.Namespace}, foundCM)
	if apierrors.IsNotFound(err) {
		log.Info("creating ConfigMap", "name", desiredCM.Name)
		if err := r.Create(ctx, desiredCM); err != nil {
			return ctrl.Result{}, err
		}
	} else if err != nil {
		return ctrl.Result{}, err
	}

	// Ensure Service
	desiredSvc := serviceFor(&webapp)
	if err := controllerutil.SetControllerReference(&webapp, desiredSvc, r.Scheme); err != nil {
		return ctrl.Result{}, err
	}

	foundSvc := &corev1.Service{}
	err = r.Get(ctx, types.NamespacedName{Name: desiredSvc.Name, Namespace: desiredSvc.Namespace}, foundSvc)
	if apierrors.IsNotFound(err) {
		log.Info("creating Service", "name", desiredSvc.Name)
		if err := r.Create(ctx, desiredSvc); err != nil {
			return ctrl.Result{}, err
		}
	} else if err != nil {
		return ctrl.Result{}, err
	}

	// Continue with other reconcile steps (Deployment, status, etc.)
	return ctrl.Result{}, nil
}

Build and run the controller

$ go build
$ make run

Typical startup logs

{"controller": "webapp", "controllerGroup": "webapp.kedloud.com", "controllerKind": "WebApp", "source": "*v1.WebApp"}
2026-06-07T11:02:28+02:00  INFO     Starting Controller
{"controller": "webapp", "controllerGroup": "webapp.kedloud.com", "controllerKind": "WebApp"}
2026-06-07T11:02:28+02:00  INFO     Starting workers
{"controller": "webapp", "controllerGroup": "webapp.kedloud.com", "controllerKind": "WebApp", "worker count": 1}

Apply your sample custom resource

$ kubectl apply -f config/samples/webapp_v1_webapp.yaml

Verify the children were created Use the app label to list the Deployment, Service, and ConfigMap created by a single WebApp resource:

$ kubectl get deployments,services,configmaps -l app=<your-webapp-name>

If you see entries for the Deployment, Service, and ConfigMap, the controller successfully executed the reconcile pattern: build desired objects, attach owner references, check for existence, and create missing children. Resources and references

Summary table

Resource Type	Purpose	Example / Note
Deployment	Runs application pods	`spec.template.metadata.labels = map[string]string{"app": w.Name}`
Service	Stable network endpoint for pods	`type: ClusterIP`, `ports: 80 -> targetPort 80`
ConfigMap	Stores configuration/data for pods	`name: w.Name + "-config"`

This completes adding a Service builder and wiring it into the reconcile loop so the WebApp controller manages Service lifecycle along with its other children.

Watch Video

Demo Add The ConfigMap Child

Owner References And Garbage Collection

Introduction to Operator Fundamentals

Custom Resource Definitions Deep Dive

Kubebuilder Scaffolding

Building The WebApp Operator Core Reconcile

Running Testing Debugging Locally

Status Conditions Events

Finalizers And Cleanup

Validation Webhooks And CEL Policies

Packaging And Distribution

Alternative Approaches Operator SDK Helm Operator

Consuming Popular Operators

Production Readiness Testing Wrap Up

Demo Add The Service Builder

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