Why can the deployment be updated successfully after the ResourceVersion is set to ""?

General Discussions
,
1

Cluster information:

Kubernetes version: v1.25.7

example

package main

import (
	"context"
	"fmt"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/tools/clientcmd"
)

func main() {
	config, err := clientcmd.BuildConfigFromFlags("", "path_to_kubeconfig")
	if err != nil {
		panic(err.Error())
	}

	clientset, err := kubernetes.NewForConfig(config)
	if err != nil {
		panic(err.Error())
	}

	aiClient, err := aiclient.NewForConfig(config)
	if err != nil {
		panic(err.Error())
	}

	deploymentsClient := clientset.AppsV1().Deployments("kube-system")
	deployment, err := deploymentsClient.Get(context.TODO(), "coredns", metav1.GetOptions{})
	if err != nil {
		panic(err.Error())
	}

	deployment.ResourceVersion = ""
	replicas := int32(3)
	deployment.Spec.Replicas = &replicas

	_, err = deploymentsClient.Update(context.TODO(), deployment, metav1.UpdateOptions{})
	if err != nil {
		panic(err.Error())
	}
}

Why can the deployment be updated successfully after the ResourceVersion is set to “”? but the custom resource cannot?

2

Clearing RV explicitly means “do not do conflict detection”. If someone else wrote to that object between the time you read it and the time you wrote it, your change will destroy theirs.