kubectl源码分析之scale

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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 ScaleOptions struct {//scale结构体
	FilenameOptions resource.FilenameOptions
	RecordFlags     *genericclioptions.RecordFlags
	PrintFlags      *genericclioptions.PrintFlags
	PrintObj        printers.ResourcePrinterFunc

	Selector        string
	All             bool
	Replicas        int
	ResourceVersion string
	CurrentReplicas int
	Timeout         time.Duration

	Recorder                     genericclioptions.Recorder
	builder                      *resource.Builder
	namespace                    string
	enforceNamespace             bool
	args                         []string
	shortOutput                  bool
	clientSet                    kubernetes.Interface
	scaler                       scale.Scaler
	unstructuredClientForMapping func(mapping *meta.RESTMapping) (resource.RESTClient, error)
	parent                       string

	genericclioptions.IOStreams
}

func NewScaleOptions(ioStreams genericclioptions.IOStreams) *ScaleOptions {
	return &ScaleOptions{//初始化结构体
		PrintFlags:      genericclioptions.NewPrintFlags("scaled"),
		RecordFlags:     genericclioptions.NewRecordFlags(),
		CurrentReplicas: -1,
		Recorder:        genericclioptions.NoopRecorder{},
		IOStreams:       ioStreams,
	}
}

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

	validArgs := []string{"deployment", "replicaset", "replicationcontroller", "statefulset"}

	cmd := &cobra.Command{//创建cobra命令
		Use:                   "scale [--resource-version=version] [--current-replicas=count] --replicas=COUNT (-f FILENAME | TYPE NAME)",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job"),
		Long:                  scaleLong,
		Example:               scaleExample,
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(o.Complete(f, cmd, args))//准备
			cmdutil.CheckErr(o.Validate(cmd))//校验
			cmdutil.CheckErr(o.RunScale())//运行
		},
		ValidArgs: validArgs,//有效参数
	}

	o.RecordFlags.AddFlags(cmd)//record选项
	o.PrintFlags.AddFlags(cmd)//打印选项

	cmd.Flags().StringVarP(&o.Selector, "selector", "l", o.Selector, "Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)")//selecor选项
	cmd.Flags().BoolVar(&o.All, "all", o.All, "Select all resources in the namespace of the specified resource types")//all选项
	cmd.Flags().StringVar(&o.ResourceVersion, "resource-version", o.ResourceVersion, i18n.T("Precondition for resource version. Requires that the current resource version match this value in order to scale."))//resource-version选项
	cmd.Flags().IntVar(&o.CurrentReplicas, "current-replicas", o.CurrentReplicas, "Precondition for current size. Requires that the current size of the resource match this value in order to scale.")//current-replicas选项
	cmd.Flags().IntVar(&o.Replicas, "replicas", o.Replicas, "The new desired number of replicas. Required.")//replicas选项
	cmd.MarkFlagRequired("replicas")//必须有
	cmd.Flags().DurationVar(&o.Timeout, "timeout", 0, "The length of time to wait before giving up on a scale operation, zero means don't wait. Any other values should contain a corresponding time unit (e.g. 1s, 2m, 3h).")//timout选项
	cmdutil.AddFilenameOptionFlags(cmd, &o.FilenameOptions, "identifying the resource to set a new size")//文件选项
	return cmd
}

//准备函数
func (o *ScaleOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []string) error {
	var err error
	o.RecordFlags.Complete(cmd)//record complete
	o.Recorder, err = o.RecordFlags.ToRecorder()//record flag转recorder
	if err != nil {
		return err
	}
	printer, err := o.PrintFlags.ToPrinter()//printflag转printer
	if err != nil {
		return err
	}
	o.PrintObj = printer.PrintObj//设置printObj函数

	o.namespace, o.enforceNamespace, err = f.ToRawKubeConfigLoader().Namespace()//设置namespace和EnforceNamespace
	if err != nil {
		return err
	}
	o.builder = f.NewBuilder()//设置builder
	o.args = args//设置参数
	o.shortOutput = cmdutil.GetFlagString(cmd, "output") == "name"//判断输出格式是否是name
	o.clientSet, err = f.KubernetesClientSet()//设置client
	if err != nil {
		return err
	}
	o.scaler, err = scaler(f)//设置scaler
	if err != nil {
		return err
	}
	o.unstructuredClientForMapping = f.UnstructuredClientForMapping//设置unstructuredClientForMapping 
	o.parent = cmd.Parent().Name()//设置父命令

	return nil
}

//校验函数
func (o *ScaleOptions) Validate(cmd *cobra.Command) error {
	if o.Replicas < 0 {//replicas不能小于0
		return fmt.Errorf("The --replicas=COUNT flag is required, and COUNT must be greater than or equal to 0")
	}

	return nil
}

//运行
func (o *ScaleOptions) RunScale() error {
	r := o.builder.
		Unstructured().
		ContinueOnError().
		NamespaceParam(o.namespace).DefaultNamespace().
		FilenameParam(o.enforceNamespace, &o.FilenameOptions).
		ResourceTypeOrNameArgs(o.All, o.args...).
		Flatten().
		LabelSelectorParam(o.Selector).
		Do()//构造result对象
	err := r.Err()
	if err != nil {
		return err
	}

	infos := []*resource.Info{}
	err = r.Visit(func(info *resource.Info, err error) error {//visit result 追加info到Infos
		if err == nil {
			infos = append(infos, info)
		}
		return nil
	})

	if len(o.ResourceVersion) != 0 && len(infos) > 1 {//如果资源版本不为空，infos大于1个则报错
		return fmt.Errorf("cannot use --resource-version with multiple resources")
	}

	// only set a precondition if the user has requested one.  A nil precondition means we can do a blind update, so
	// we avoid a Scale GET that may or may not succeed
	var precondition *scale.ScalePrecondition
	if o.CurrentReplicas != -1 || len(o.ResourceVersion) > 0 {//如果当前副本不等于-1，资源版本有值
		precondition = &scale.ScalePrecondition{Size: o.CurrentReplicas, ResourceVersion: o.ResourceVersion}//设置precondition 
	}
	retry := scale.NewRetryParams(1*time.Second, 5*time.Minute)//设置retry 

	var waitForReplicas *scale.RetryParams
	if o.Timeout != 0 {//timout不为0
		waitForReplicas = scale.NewRetryParams(1*time.Second, timeout)//设置waitForReplicas 
	}

	counter := 0
	err = r.Visit(func(info *resource.Info, err error) error {//visit result
		if err != nil {
			return err
		}

		mapping := info.ResourceMapping()//获取info的Mapping
		if err := o.scaler.Scale(info.Namespace, info.Name, uint(o.Replicas), precondition, retry, waitForReplicas, mapping.Resource); err != nil {//执行scale
			return err
		}

		// if the recorder makes a change, compute and create another patch
		if mergePatch, err := o.Recorder.MakeRecordMergePatch(info.Object); err != nil {//生成record补丁
			klog.V(4).Infof("error recording current command: %v", err)
		} else if len(mergePatch) > 0 {//如果补丁有值
			client, err := o.unstructuredClientForMapping(mapping)//获取client
			if err != nil {
				return err
			}
			helper := resource.NewHelper(client, mapping)//获取helper
			if _, err := helper.Patch(info.Namespace, info.Name, types.MergePatchType, mergePatch, nil); err != nil {//应用补丁到服务端
				klog.V(4).Infof("error recording reason: %v", err)
			}
		}

		counter++//counter自增
		return o.PrintObj(info.Object, o.Out)//打印结果
	})
	if err != nil {
		return err
	}
	if counter == 0 {//count等于0报错
		return fmt.Errorf("no objects passed to scale")
	}
	return nil
}

//执行scale
func (s *genericScaler) Scale(namespace, resourceName string, newSize uint, preconditions *ScalePrecondition, retry, waitForReplicas *RetryParams, gvr schema.GroupVersionResource) error {
	if retry == nil {
		// make it try only once, immediately
		retry = &RetryParams{Interval: time.Millisecond, Timeout: time.Millisecond}
	}
	cond := ScaleCondition(s, preconditions, namespace, resourceName, newSize, nil, gvr)//构造scale 条件
	if err := wait.PollImmediate(retry.Interval, retry.Timeout, cond); err != nil {//立即整形scale
		return err
	}
	if waitForReplicas != nil {
		return WaitForScaleHasDesiredReplicas(s.scaleNamespacer, gvr.GroupResource(), resourceName, namespace, newSize, waitForReplicas)//等待scale完成
	}
	return nil
}