为什么kubeadm可以用于生产？

第一是kubeadm已经被官方收编，可以在官网文档中找到它的身影。

另外一个是kubeadm是用golang调用k8s的命令去执行创建k8s集群的。查看一下kubeadm的代码即可知道。

本文来源于csdn作者 sunican

挨个打开目录查看文件可知，源代码基本就在kinder目录。为什么这个目录名叫kinder呢？熟悉k8s项目的同学应该知道，有个项目叫kind。

查看roadmap.md可知，原来kinder(或者说kubeadm)作者从kind项目得到了灵感。

查看kinder/main.go可知，主体代码在kinder/cmd/kinder目录下

import (
    "k8s.io/kubeadm/kinder/cmd/kinder"
)

func main() {
    kinder.Main()
}

根据这个去看一下kinder.go文件，可以看到是Main函数调用了Run函数，而Run函数就一行

return NewCommand().Execute()

再找到NewCommand函数的定义就会发现，这个就是我们今天要看的主角。它借用了cobra来对构建k8s用到的命令进行统一的封装和调用。

func NewCommand() *cobra.Command {
    flags := &Flags{}
    cmd := &cobra.Command{
        Args:  cobra.NoArgs,
        Use:   "kinder",
        Short: "kinder is an example of kind(https://github.com/kubernetes-sigs/kind) used as a library",
        Long: "   _  ___         _\n" +
            "  | |/ (_)_ _  __| |___ _ _\n" +
            "  | ' <| | ' \\/ _` / -_) '_|\n" +
            "  |_|\\_\\_|_||_\\__,_\\___|_|\n\n" +
            "kinder is an example of kind(https://github.com/kubernetes-sigs/kind) used as a library.\n\n" +
            "All the kind commands will be available in kinder, side by side with additional commands \n" +
            "designed for helping kubeadm contributors.\n\n" +
            "kinder is still a work in progress. Test It, Break It, Send feedback!",
        PersistentPreRunE: func(cmd *cobra.Command, args []string) error {
            return runE(flags, cmd, args)
        },
        SilenceUsage: true,
        Version:      constants.KinderVersion,
    }
    cmd.PersistentFlags().StringVar(
        &flags.LogLevel,
        "loglevel",
        defaultLevel.String(),
        "logrus log level [panic, fatal, error, warning, info, debug, trace]",
    )

    logger := kindcmd.NewLogger()
    ioStreams := kindcmd.StandardIOStreams()

    // add kind top level subcommands re-used without changes
    cmd.AddCommand(kinddelete.NewCommand(logger, ioStreams))
    cmd.AddCommand(kindexport.NewCommand(logger, ioStreams))

    // add kind commands customized in kind
    cmd.AddCommand(build.NewCommand())
    cmd.AddCommand(create.NewCommand())
    cmd.AddCommand(version.NewCommand())
    cmd.AddCommand(get.NewCommand())

    // add kinder only commands
    cmd.AddCommand(cp.NewCommand())
    cmd.AddCommand(do.NewCommand())
    cmd.AddCommand(exec.NewCommand())
    cmd.AddCommand(test.NewCommand())

    return cmd
}

cmd对应的每个函数调用，大家可以自行下载代码之后查看。今天分享就到这里。