kubectl源码分析之cp

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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 CopyOptions struct {//cp结构体
	Container  string
	Namespace  string
	NoPreserve bool

	ClientConfig      *restclient.Config
	Clientset         kubernetes.Interface
	ExecParentCmdName string

	genericclioptions.IOStreams
}

func NewCopyOptions(ioStreams genericclioptions.IOStreams) *CopyOptions {
	return &CopyOptions{//初始化结构体
		IOStreams: ioStreams,
	}
}

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

	cmd := &cobra.Command{//创建cobra命令
		Use:                   "cp <file-spec-src> <file-spec-dest>",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Copy files and directories to and from containers."),
		Long:                  "Copy files and directories to and from containers.",
		Example:               cpExample,
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(o.Complete(f, cmd))//准备
			cmdutil.CheckErr(o.Run(args))//运行
		},
	}
	cmd.Flags().StringVarP(&o.Container, "container", "c", o.Container, "Container name. If omitted, the first container in the pod will be chosen")//容器选项
	cmd.Flags().BoolVarP(&o.NoPreserve, "no-preserve", "", false, "The copied file/directory's ownership and permissions will not be preserved in the container")//no-preserve选项

	return cmd
}

type fileSpec struct {//文件结构体
	PodNamespace string
	PodName      string
	File         string
}

//准备函数
func (o *CopyOptions) Complete(f cmdutil.Factory, cmd *cobra.Command) error {
	if cmd.Parent() != nil {//设置父命令名称
		o.ExecParentCmdName = cmd.Parent().CommandPath()
	}

	var err error
	o.Namespace, _, err = f.ToRawKubeConfigLoader().Namespace()//设置名称空间
	if err != nil {
		return err
	}

	o.Clientset, err = f.KubernetesClientSet()//设置Clientset
	if err != nil {
		return err
	}

	o.ClientConfig, err = f.ToRESTConfig()//设置restconfig
	if err != nil {
		return err
	}
	return nil
}

// Validate makes sure provided values for CopyOptions are valid
//校验
func (o *CopyOptions) Validate(cmd *cobra.Command, args []string) error {
	if len(args) != 2 {//参数必须是两个
		return cmdutil.UsageErrorf(cmd, cpUsageStr)
	}
	return nil
}

//运行
func (o *CopyOptions) Run(args []string) error {
	if len(args) < 2 {//参数小于2个报错
		return fmt.Errorf("source and destination are required")
	}
	srcSpec, err := extractFileSpec(args[0])//从参数抽取源文件规范
	if err != nil {
		return err
	}
	destSpec, err := extractFileSpec(args[1])//从arg抽取目标文件规范
	if err != nil {
		return err
	}

	if len(srcSpec.PodName) != 0 && len(destSpec.PodName) != 0 {//源pod和目标pod都不为空
		if _, err := os.Stat(args[0]); err == nil {//参数0，文件存在
			return o.copyToPod(fileSpec{File: args[0]}, destSpec, &exec.ExecOptions{})//拷贝到pod
		}
		return fmt.Errorf("src doesn't exist in local filesystem")//报错
	}

	if len(srcSpec.PodName) != 0 {//源pod不额外空
		return o.copyFromPod(srcSpec, destSpec)//从pod拷贝到本地
	}
	if len(destSpec.PodName) != 0 {//目标pod不为空
		return o.copyToPod(srcSpec, destSpec, &exec.ExecOptions{})//从本地拷贝到目标
	}
	return fmt.Errorf("one of src or dest must be a remote file specification")//报错
}

func extractFileSpec(arg string) (fileSpec, error) {//抽取文件规范
	if i := strings.Index(arg, ":"); i == -1 {//没有冒号
		return fileSpec{File: arg}, nil
	} else if i > 0 {
		file := arg[i+1:]
		pod := arg[:i]
		pieces := strings.Split(pod, "/")//用/分割，
		if len(pieces) == 1 {//分割后为1个，指定pod名称
			return fileSpec{
				PodName: pieces[0],
				File:    file,
			}, nil
		}
		if len(pieces) == 2 {//分割后参数为2个，指定名称空间和pod名称
			return fileSpec{
				PodNamespace: pieces[0],
				PodName:      pieces[1],
				File:         file,
			}, nil
		}
	}

	return fileSpec{}, errFileSpecDoesntMatchFormat
}

//拷贝到pod
func (o *CopyOptions) copyToPod(src, dest fileSpec, options *exec.ExecOptions) error {
	if len(src.File) == 0 || len(dest.File) == 0 {// 文件名为空报错
		return errFileCannotBeEmpty
	}
	reader, writer := io.Pipe()//创建管道

	// strip trailing slash (if any)
	if dest.File != "/" && strings.HasSuffix(string(dest.File[len(dest.File)-1]), "/") {//目标文件不为/，并且目标文件有/结尾
		dest.File = dest.File[:len(dest.File)-1]//去掉目标文件末尾/
	}

	if err := o.checkDestinationIsDir(dest); err == nil {//如果目标是目录
		// If no error, dest.File was found to be a directory.
		// Copy specified src into it
		dest.File = dest.File + "/" + path.Base(src.File)//目标文件为目标加源文件
	}

	go func() {
		defer writer.Close()
		err := makeTar(src.File, dest.File, writer)//创建tar文件
		cmdutil.CheckErr(err)
	}()
	var cmdArr []string

	// TODO: Improve error messages by first testing if 'tar' is present in the container?
	if o.NoPreserve {//如果指定no-preserve
		cmdArr = []string{"tar", "--no-same-permissions", "--no-same-owner", "-xmf", "-"}//构造命令行
	} else {
		cmdArr = []string{"tar", "-xmf", "-"}
	}
	destDir := path.Dir(dest.File)//获取目标文件目录
	if len(destDir) > 0 {//如果目标文件目录有值
		cmdArr = append(cmdArr, "-C", destDir)//追加命令
	}

	options.StreamOptions = exec.StreamOptions{//构造流选项
		IOStreams: genericclioptions.IOStreams{
			In:     reader,
			Out:    o.Out,
			ErrOut: o.ErrOut,
		},
		Stdin: true,

		Namespace: dest.PodNamespace,
		PodName:   dest.PodName,
	}

	options.Command = cmdArr
	options.Executor = &exec.DefaultRemoteExecutor{}
	return o.execute(options)//执行拷贝
}

// 执行拷贝
func (o *CopyOptions) execute(options *exec.ExecOptions) error {
	if len(options.Namespace) == 0 {//如果名称空间为空，用o的名称空间
		options.Namespace = o.Namespace
	}

	if len(o.Container) > 0 {//如果container不为空，设置container
		options.ContainerName = o.Container
	}

	options.Config = o.ClientConfig//设置restconfig
	options.PodClient = o.Clientset.CoreV1()//设置podclient

	if err := options.Validate(); err != nil {//执行校验
		return err
	}

	if err := options.Run(); err != nil {//运行拷贝
		return err
	}
	return nil
}

//创建tar文件
func makeTar(srcPath, destPath string, writer io.Writer) error {
	// TODO: use compression here?
	tarWriter := tar.NewWriter(writer)//包装writer
	defer tarWriter.Close()

	srcPath = path.Clean(srcPath)//源路径
	destPath = path.Clean(destPath)//目标路径
	return recursiveTar(path.Dir(srcPath), path.Base(srcPath), path.Dir(destPath), path.Base(destPath), tarWriter)//递归创建tar
}

//从pod拷贝到本地
func (o *CopyOptions) copyFromPod(src, dest fileSpec) error {
	if len(src.File) == 0 || len(dest.File) == 0 {//源文件和目标文件不能为空
		return errFileCannotBeEmpty
	}

	reader, outStream := io.Pipe()//创建pipe
	options := &exec.ExecOptions{//构造exec选项
		StreamOptions: exec.StreamOptions{
			IOStreams: genericclioptions.IOStreams{
				In:     nil,
				Out:    outStream,
				ErrOut: o.Out,
			},

			Namespace: src.PodNamespace,
			PodName:   src.PodName,
		},

		// TODO: Improve error messages by first testing if 'tar' is present in the container?
		Command:  []string{"tar", "cf", "-", src.File},
		Executor: &exec.DefaultRemoteExecutor{},
	}

	go func() {
		defer outStream.Close()
		err := o.execute(options)//执行拷贝
		cmdutil.CheckErr(err)
	}()
	prefix := getPrefix(src.File)//获取prefix
	prefix = path.Clean(prefix)
	// remove extraneous path shortcuts - these could occur if a path contained extra "../"
	// and attempted to navigate beyond "/" in a remote filesystem
	prefix = stripPathShortcuts(prefix)//修剪prefix
	return o.untarAll(src, reader, dest.File, prefix)//执行解压缩
}