kubectl源码分析之cordon and uncordon

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原创最新推荐文章于 2026-04-21 05:16:24 发布 980 阅读 AI 写同款· GEO 优化 ›

kubectl滚动更新资源 rollout Manage the rollout of a resource. Valid resource types include: * deployments * daemonsets * statefulsets Examples: # Rollback to the previous deployment kubectl rollout undo deployment/abc # Check the rollout status of a da 阅读详情

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目前刚开始写一个月，一共写了18篇原创文章，文章目录如下：

istio多集群探秘，部署了50次多集群后我得出的结论

istio多集群链路追踪，附实操视频

istio防故障利器，你知道几个,istio新手不要读，太难！

istio业务权限控制，原来可以这么玩

istio实现非侵入压缩，微服务之间如何实现压缩

不懂envoyfilter也敢说精通istio系列-http-rbac-不要只会用AuthorizationPolicy配置权限

不懂envoyfilter也敢说精通istio系列-02-http-corsFilter-不要只会vs

不懂envoyfilter也敢说精通istio系列-03-http-csrf filter-再也不用再代码里写csrf逻辑了

不懂envoyfilter也敢说精通istio系列http-jwt_authn-不要只会RequestAuthorization

不懂envoyfilter也敢说精通istio系列-05-fault-filter-故障注入不止是vs

不懂envoyfilter也敢说精通istio系列-06-http-match-配置路由不只是vs

不懂envoyfilter也敢说精通istio系列-07-负载均衡配置不止是dr

不懂envoyfilter也敢说精通istio系列-08-连接池和断路器

不懂envoyfilter也敢说精通istio系列-09-http-route filter

不懂envoyfilter也敢说精通istio系列-network filter-redis proxy

不懂envoyfilter也敢说精通istio系列-network filter-HttpConnectionManager

不懂envoyfilter也敢说精通istio系列-ratelimit-istio ratelimit完全手册

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type DrainCmdOptions struct {//drain结构体
	PrintFlags *genericclioptions.PrintFlags
	ToPrinter  func(string) (printers.ResourcePrinterFunc, error)

	Namespace string

	drainer   *drain.Helper
	nodeInfos []*resource.Info

	genericclioptions.IOStreams
}

//创建cordon命令
func NewCmdCordon(f cmdutil.Factory, ioStreams genericclioptions.IOStreams) *cobra.Command {
	o := NewDrainCmdOptions(f, ioStreams)//初始化结构体

	cmd := &cobra.Command{//创建cobra命令
		Use:                   "cordon NODE",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Mark node as unschedulable"),
		Long:                  cordonLong,
		Example:               cordonExample,
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(o.Complete(f, cmd, args))//准备
			cmdutil.CheckErr(o.RunCordonOrUncordon(true))//运行
		},
	}
	cmd.Flags().StringVarP(&o.drainer.Selector, "selector", "l", o.drainer.Selector, "Selector (label query) to filter on")//selector选项
	cmdutil.AddDryRunFlag(cmd)//干跑选项
	return cmd
}

//创建uncordon命令
func NewCmdUncordon(f cmdutil.Factory, ioStreams genericclioptions.IOStreams) *cobra.Command {
	o := NewDrainCmdOptions(f, ioStreams)//初始化结构体

	cmd := &cobra.Command{//创建cobra命令
		Use:                   "uncordon NODE",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Mark node as schedulable"),
		Long:                  uncordonLong,
		Example:               uncordonExample,
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(o.Complete(f, cmd, args))//准备
			cmdutil.CheckErr(o.RunCordonOrUncordon(false))//运行
		},
	}
	cmd.Flags().StringVarP(&o.drainer.Selector, "selector", "l", o.drainer.Selector, "Selector (label query) to filter on")//selector选项
	cmdutil.AddDryRunFlag(cmd)//干跑选项
	return cmd
}

//准备函数
func (o *DrainCmdOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []string) error {
	var err error

	if len(args) == 0 && !cmd.Flags().Changed("selector") {//如果参数和selector都没指定则报错
		return cmdutil.UsageErrorf(cmd, fmt.Sprintf("USAGE: %s [flags]", cmd.Use))
	}
	if len(args) > 0 && len(o.drainer.Selector) > 0 {//如果参数和selector同时指定则报错
		return cmdutil.UsageErrorf(cmd, "error: cannot specify both a node name and a --selector option")
	}

	o.drainer.DryRun = cmdutil.GetDryRunFlag(cmd)//设置干跑

	if o.drainer.Client, err = f.KubernetesClientSet(); err != nil {//设置clientset
		return err
	}

	if len(o.drainer.PodSelector) > 0 {//解析podSelector
		if _, err := labels.Parse(o.drainer.PodSelector); err != nil {
			return errors.New("--pod-selector=<pod_selector> must be a valid label selector")
		}
	}

	o.nodeInfos = []*resource.Info{}//创建info对象

	o.Namespace, _, err = f.ToRawKubeConfigLoader().Namespace()//设置Namespace
	if err != nil {
		return err
	}

	o.ToPrinter = func(operation string) (printers.ResourcePrinterFunc, error) {//设置printflag转printer函数
		o.PrintFlags.NamePrintFlags.Operation = operation
		if o.drainer.DryRun {
			o.PrintFlags.Complete("%s (dry run)")
		}

		printer, err := o.PrintFlags.ToPrinter()
		if err != nil {
			return nil, err
		}

		return printer.PrintObj, nil
	}

	builder := f.NewBuilder().
		WithScheme(scheme.Scheme, scheme.Scheme.PrioritizedVersionsAllGroups()...).
		NamespaceParam(o.Namespace).DefaultNamespace().
		ResourceNames("nodes", args...).
		SingleResourceType().
		Flatten()//构造result对象

	if len(o.drainer.Selector) > 0 {
		builder = builder.LabelSelectorParam(o.drainer.Selector).
			ResourceTypes("nodes")
	}

	r := builder.Do()//构造result对象

	if err = r.Err(); err != nil {
		return err
	}

	return r.Visit(func(info *resource.Info, err error) error {//visit result对象
		if err != nil {
			return err
		}
		if info.Mapping.Resource.GroupResource() != (schema.GroupResource{Group: "", Resource: "nodes"}) {//判断是否node
			return fmt.Errorf("error: expected resource of type node, got %q", info.Mapping.Resource)
		}

		o.nodeInfos = append(o.nodeInfos, info)//append node info
		return nil
	})
}

//执行cordon或uncordon
func (o *DrainCmdOptions) RunCordonOrUncordon(desired bool) error {
	cordonOrUncordon := "cordon"//默认是cordon
	if !desired {// 如果desired为false，则为uncordon
		cordonOrUncordon = "un" + cordonOrUncordon
	}

	for _, nodeInfo := range o.nodeInfos {//遍历info

		printError := func(err error) {//打印错误函数
			fmt.Fprintf(o.ErrOut, "error: unable to %s node %q: %v\n", cordonOrUncordon, nodeInfo.Name, err)
		}

		gvk := nodeInfo.ResourceMapping().GroupVersionKind//获取info的gvk
		if gvk.Kind == "Node" {//如果kind为node
			c, err := drain.NewCordonHelperFromRuntimeObject(nodeInfo.Object, scheme.Scheme, gvk)//构造cordon帮助工具
			if err != nil {
				printError(err)
				continue
			}

			if updateRequired := c.UpdateIfRequired(desired); !updateRequired {//判断是否需要更新资源
				printObj, err := o.ToPrinter(already(desired))//printflag转printer
				if err != nil {
					fmt.Fprintf(o.ErrOut, "error: %v\n", err)
					continue
				}
				printObj(nodeInfo.Object, o.Out)//打印结果
			} else {//如果需要更新资源
				if !o.drainer.DryRun {//如果非干盘
					err, patchErr := c.PatchOrReplace(o.drainer.Client)//应用补丁到服务器
					if patchErr != nil {
						printError(patchErr)
					}
					if err != nil {
						printError(err)
						continue
					}
				}
				printObj, err := o.ToPrinter(changed(desired))//printflag转printer
				if err != nil {
					fmt.Fprintf(o.ErrOut, "%v\n", err)
					continue
				}
				printObj(nodeInfo.Object, o.Out)//打印结果
			}
		} else {
			printObj, err := o.ToPrinter("skipped")//printflag转printer
			if err != nil {
				fmt.Fprintf(o.ErrOut, "%v\n", err)
				continue
			}
			printObj(nodeInfo.Object, o.Out)//打印跳过结果
		}
	}

	return nil
}