	// Get the deployment with the name specified in Foo.spec
	deployment, err := c.deploymentsLister.Deployments(foo.Namespace).Get(deploymentName)
	// If the resource doesn't exist, we'll create it
	if errors.IsNotFound(err) {
		deployment, err = c.kubeclientset.AppsV1().Deployments(foo.Namespace).Create(ctx, newDeployment(foo), metav1.CreateOptions{FieldManager: FieldManager})
	}
…
	// If this number of the replicas on the Foo resource is specified, and the
	// number does not equal the current desired replicas on the Deployment, we
	// should update the Deployment resource.
	if foo.Spec.Replicas != nil && *foo.Spec.Replicas != *deployment.Spec.Replicas {
		logger.V(4).Info("Update deployment resource", "currentReplicas", *deployment.Spec.Replicas, "desiredReplicas", *foo.Spec.Replicas)
		deployment, err = c.kubeclientset.AppsV1().Deployments(foo.Namespace).Update(ctx, newDeployment(foo), metav1.UpdateOptions{FieldManager: FieldManager})
	}
…
	// Finally, we update the status block of the Foo resource to reflect the
	// current state of the world
	err = c.updateFooStatus(ctx, foo, deployment)

Warm-up