kubectl源码分析之autoscale

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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 AutoscaleOptions struct {//autoscale结构体
  FilenameOptions *resource.FilenameOptions

  RecordFlags *genericclioptions.RecordFlags
  Recorder    genericclioptions.Recorder

  PrintFlags *genericclioptions.PrintFlags
  ToPrinter  func(string) (printers.ResourcePrinter, error)

  Name       string
  Generator  string
  Min        int32
  Max        int32
  CPUPercent int32

  createAnnotation bool
  args             []string
  enforceNamespace bool
  namespace        string
  dryRun           bool
  builder          *resource.Builder
  generatorFunc    func(string, *meta.RESTMapping) (generate.StructuredGenerator, error)

  HPAClient         autoscalingv1client.HorizontalPodAutoscalersGetter
  scaleKindResolver scale.ScaleKindResolver

  genericclioptions.IOStreams
}

func NewAutoscaleOptions(ioStreams genericclioptions.IOStreams) *AutoscaleOptions {
  return &AutoscaleOptions{//初始化结构体
    PrintFlags:      genericclioptions.NewPrintFlags("autoscaled").WithTypeSetter(scheme.Scheme),
    FilenameOptions: &resource.FilenameOptions{},
    RecordFlags:     genericclioptions.NewRecordFlags(),
    Recorder:        genericclioptions.NoopRecorder{},

    IOStreams: ioStreams,
  }
}

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

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

  cmd := &cobra.Command{//创建cobra命令
    Use:                   "autoscale (-f FILENAME | TYPE NAME | TYPE/NAME) [--min=MINPODS] --max=MAXPODS [--cpu-percent=CPU]",
    DisableFlagsInUseLine: true,
    Short:                 i18n.T("Auto-scale a Deployment, ReplicaSet, or ReplicationController"),
    Long:                  autoscaleLong,
    Example:               autoscaleExample,
    Run: func(cmd *cobra.Command, args []string) {
      cmdutil.CheckErr(o.Complete(f, cmd, args))//准备
      cmdutil.CheckErr(o.Validate())//校验
      cmdutil.CheckErr(o.Run())//运行
    },
    ValidArgs: validArgs,//有效参数
  }

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

  cmd.Flags().StringVar(&o.Generator, "generator", generateversioned.HorizontalPodAutoscalerV1GeneratorName, i18n.T("The name of the API generator to use. Currently there is only 1 generator."))//generator选项
  cmd.Flags().Int32Var(&o.Min, "min", -1, "The lower limit for the number of pods that can be set by the autoscaler. If it's not specified or negative, the server will apply a default value.")//min选项
  cmd.Flags().Int32Var(&o.Max, "max", -1, "The upper limit for the number of pods that can be set by the autoscaler. Required.")//max选项
  cmd.MarkFlagRequired("max")//max是必须的
  cmd.Flags().Int32Var(&o.CPUPercent, "cpu-percent", -1, fmt.Sprintf("The target average CPU utilization (represented as a percent of requested CPU) over all the pods. If it's not specified or negative, a default autoscaling policy will be used."))//cpu-percent选项
  cmd.Flags().StringVar(&o.Name, "name", "", i18n.T("The name for the newly created object. If not specified, the name of the input resource will be used."))//hpa名称
  cmdutil.AddDryRunFlag(cmd)//干跑选项
  cmdutil.AddFilenameOptionFlags(cmd, o.FilenameOptions, "identifying the resource to autoscale.")//文件选项
  cmdutil.AddApplyAnnotationFlags(cmd)//save-config选项
  return cmd
}

//准备方法
func (o *AutoscaleOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []string) error {
  var err error
  o.dryRun = cmdutil.GetFlagBool(cmd, "dry-run")//设置干跑
  o.createAnnotation = cmdutil.GetFlagBool(cmd, cmdutil.ApplyAnnotationsFlag)//设置是否创建last-applied-configuration注解
  o.builder = f.NewBuilder()//设置builder
  discoveryClient, err := f.ToDiscoveryClient()//获取client
  if err != nil {
    return err
  }
  o.scaleKindResolver = scale.NewDiscoveryScaleKindResolver(discoveryClient)//设置scaleKindResolver
  o.args = args//设置参数
  o.RecordFlags.Complete(cmd)//record complete

  o.Recorder, err = o.RecordFlags.ToRecorder()//record flag转recorder
  if err != nil {
    return err
  }

  kubeClient, err := f.KubernetesClientSet()//设置kubeClient
  if err != nil {
    return err
  }
  o.HPAClient = kubeClient.AutoscalingV1()//设置HPAclient

  // get the generator
  o.generatorFunc = func(name string, mapping *meta.RESTMapping) (generate.StructuredGenerator, error) {//判断genetator，生成generator对象
    switch o.Generator {
    case generateversioned.HorizontalPodAutoscalerV1GeneratorName:
      return &generateversioned.HorizontalPodAutoscalerGeneratorV1{
        Name:               name,
        MinReplicas:        o.Min,
        MaxReplicas:        o.Max,
        CPUPercent:         o.CPUPercent,
        ScaleRefName:       name,
        ScaleRefKind:       mapping.GroupVersionKind.Kind,
        ScaleRefAPIVersion: mapping.GroupVersionKind.GroupVersion().String(),
      }, nil
    default:
      return nil, cmdutil.UsageErrorf(cmd, "Generator %s not supported. ", o.Generator)
    }
  }

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

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

    return o.PrintFlags.ToPrinter()
  }

  return nil
}

// Validate checks that the provided attach options are specified.
//校验函数
func (o *AutoscaleOptions) Validate() error {
  if o.Max < 1 {//max不能小于1
    return fmt.Errorf("--max=MAXPODS is required and must be at least 1, max: %d", o.Max)
  }
  if o.Max < o.Min {//max必须大于min
    return fmt.Errorf("--max=MAXPODS must be larger or equal to --min=MINPODS, max: %d, min: %d", o.Max, o.Min)
  }

  return nil
}

//运行
func (o *AutoscaleOptions) Run() error {
  r := o.builder.
    Unstructured().
    ContinueOnError().
    NamespaceParam(o.namespace).DefaultNamespace().
    FilenameParam(o.enforceNamespace, o.FilenameOptions).
    ResourceTypeOrNameArgs(false, o.args...).
    Flatten().
    Do()//构造result对象
  if err := r.Err(); err != nil {
    return err
  }

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

    mapping := info.ResourceMapping()//获取info的mapping
    gvr := mapping.GroupVersionKind.GroupVersion().WithResource(mapping.Resource.Resource)//获取groupverisonresource
    if _, err := o.scaleKindResolver.ScaleForResource(gvr); err != nil {//判断资源是否可以scale
      return fmt.Errorf("cannot autoscale a %v: %v", mapping.GroupVersionKind.Kind, err)
    }

    generator, err := o.generatorFunc(info.Name, mapping)//射程generator对象
    if err != nil {
      return err
    }

    // Generate new object
    object, err := generator.StructuredGenerate()//用generator生成结构化对象
    if err != nil {
      return err
    }
    hpa, ok := object.(*autoscalingv1.HorizontalPodAutoscaler)//对象转hpa对象
    if !ok {
      return fmt.Errorf("generator made %T, not autoscalingv1.HorizontalPodAutoscaler", object)
    }

    if err := o.Recorder.Record(hpa); err != nil {//判断是否创建change-cause注解
      klog.V(4).Infof("error recording current command: %v", err)
    }

    if o.dryRun {//如果是干跑
      count++

      printer, err := o.ToPrinter("created")//printflag转printer
      if err != nil {
        return err
      }
      return printer.PrintObj(hpa, o.Out)//打印结果
    }

    if err := util.CreateOrUpdateAnnotation(o.createAnnotation, hpa, scheme.DefaultJSONEncoder()); err != nil {//hpa对象是否创建last-applied-configuration注解
      return err
    }

    actualHPA, err := o.HPAClient.HorizontalPodAutoscalers(o.namespace).Create(hpa)//创建hpa资源到服务端
    if err != nil {
      return err
    }

    count++
    printer, err := o.ToPrinter("autoscaled")//printflag转printer
    if err != nil {
      return err
    }
    return printer.PrintObj(actualHPA, o.Out)//打印结果
  })
  if err != nil {
    return err
  }
  if count == 0 {
    return fmt.Errorf("no objects passed to autoscale")
  }
  return nil
}