syncer

package main

import (
	"context"

	appsv1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/kubernetes/scheme"
	"k8s.io/client-go/tools/record"
	logf "sigs.k8s.io/controller-runtime/pkg/runtime/log"

	"github.com/fasterbytes/controller-util/syncer"
)

var (
	recorder record.EventRecorder
	owner    runtime.Object
	log      = logf.Log.WithName("controllerutil-examples")
)

func NewDeploymentSyncer(owner runtime.Object) syncer.Interface {
	deploy := &appsv1.Deployment{
		ObjectMeta: metav1.ObjectMeta{
			Name:      "example",
			Namespace: "default",
		},
	}

	// c is client.Client
	return syncer.NewObjectSyncer("ExampleDeployment", owner, deploy, c, scheme.Scheme, func() error {
		// Deployment selector is immutable so we set this value only if
		// a new object is going to be created
		if deploy.ObjectMeta.CreationTimestamp.IsZero() {
			deploy.Spec.Selector = &metav1.LabelSelector{
				MatchLabels: map[string]string{"foo": "bar"},
			}
		}

		// update the Deployment pod template
		deploy.Spec.Template = corev1.PodTemplateSpec{
			ObjectMeta: metav1.ObjectMeta{
				Labels: map[string]string{
					"foo": "bar",
				},
			},
			Spec: corev1.PodSpec{
				Containers: []corev1.Container{
					{
						Name:  "busybox",
						Image: "busybox",
					},
				},
			},
		}

		return nil
	})
}

func main() {
	// recorder is record.EventRecorder
	// owner is the owner for the syncer subject

	deploymentSyncer := NewDeploymentSyncer(owner)
	err := syncer.Sync(context.TODO(), deploymentSyncer, recorder)
	if err != nil {
		log.Error(err, "unable to sync")
	}
}

Output: