kubectl源码分析之create命令

发布一个k8s部署视频：https://edu.youkuaiyun.com/course/detail/26967

课程内容：各种k8s部署方式。包括minikube部署，kubeadm部署，kubeasz部署，rancher部署，k3s部署。包括开发测试环境部署k8s，和生产环境部署k8s。

腾讯课堂连接地址https://ke.qq.com/course/478827?taid=4373109931462251&tuin=ba64518

第二个视频发布  https://edu.youkuaiyun.com/course/detail/27109

腾讯课堂连接地址https://ke.qq.com/course/484107?tuin=ba64518

介绍主要的k8s资源的使用配置和命令。包括configmap，pod，service，replicaset，namespace，deployment，daemonset，ingress，pv，pvc，sc，role，rolebinding，clusterrole，clusterrolebinding，secret，serviceaccount，statefulset，job，cronjob，podDisruptionbudget，podSecurityPolicy,networkPolicy,resourceQuota，limitrange，endpoint，event，conponentstatus，node，apiservice，controllerRevision等。

第三个视频发布：https://edu.youkuaiyun.com/course/detail/27574

详细介绍helm命令，学习helm chart语法，编写helm chart。深入分析各项目源码，学习编写helm插件

第四个课程发布：https://edu.youkuaiyun.com/course/detail/28488

本课程将详细介绍k8s所有命令，以及命令的go源码分析，学习知其然，知其所以然

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func NewCmdCreate(f cmdutil.Factory, ioStreams genericclioptions.IOStreams) *cobra.Command {
	o := NewCreateOptions(ioStreams)

	cmd := &cobra.Command{
		Use:                   "create -f FILENAME",
		DisableFlagsInUseLine: true,
		Short:                 i18n.T("Create a resource from a file or from stdin."),
		Long:                  createLong,
		Example:               createExample,
		Run: func(cmd *cobra.Command, args []string) {
			if cmdutil.IsFilenameSliceEmpty(o.FilenameOptions.Filenames, o.FilenameOptions.Kustomize) {
				ioStreams.ErrOut.Write([]byte("Error: must specify one of -f and -k\n\n"))
				defaultRunFunc := cmdutil.DefaultSubCommandRun(ioStreams.ErrOut)
				defaultRunFunc(cmd, args)
				return
			}
			cmdutil.CheckErr(o.Complete(f, cmd))
			cmdutil.CheckErr(o.ValidateArgs(cmd, args))
			cmdutil.CheckErr(o.RunCreate(f, cmd))
		},
	}

	// bind flag structs
	o.RecordFlags.AddFlags(cmd)

	usage := "to use to create the resource"
	cmdutil.AddFilenameOptionFlags(cmd, &o.FilenameOptions, usage)
	cmdutil.AddValidateFlags(cmd)
	cmd.Flags().BoolVar(&o.EditBeforeCreate, "edit", o.EditBeforeCreate, "Edit the API resource before creating")
	cmd.Flags().Bool("windows-line-endings", runtime.GOOS == "windows",
		"Only relevant if --edit=true. Defaults to the line ending native to your platform.")
	cmdutil.AddApplyAnnotationFlags(cmd)
	cmdutil.AddDryRunFlag(cmd)
	cmd.Flags().StringVarP(&o.Selector, "selector", "l", o.Selector, "Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)")
	cmd.Flags().StringVar(&o.Raw, "raw", o.Raw, "Raw URI to POST to the server.  Uses the transport specified by the kubeconfig file.")

	o.PrintFlags.AddFlags(cmd)

	// create subcommands
	cmd.AddCommand(NewCmdCreateNamespace(f, ioStreams))
	cmd.AddCommand(NewCmdCreateQuota(f, ioStreams))
	cmd.AddCommand(NewCmdCreateSecret(f, ioStreams))
	cmd.AddCommand(NewCmdCreateConfigMap(f, ioStreams))
	cmd.AddCommand(NewCmdCreateServiceAccount(f, ioStreams))
	cmd.AddCommand(NewCmdCreateService(f, ioStreams))
	cmd.AddCommand(NewCmdCreateDeployment(f, ioStreams))
	cmd.AddCommand(NewCmdCreateClusterRole(f, ioStreams))
	cmd.AddCommand(NewCmdCreateClusterRoleBinding(f, ioStreams))
	cmd.AddCommand(NewCmdCreateRole(f, ioStreams))
	cmd.AddCommand(NewCmdCreateRoleBinding(f, ioStreams))
	cmd.AddCommand(NewCmdCreatePodDisruptionBudget(f, ioStreams))
	cmd.AddCommand(NewCmdCreatePriorityClass(f, ioStreams))
	cmd.AddCommand(NewCmdCreateJob(f, ioStreams))
	cmd.AddCommand(NewCmdCreateCronJob(f, ioStreams))
	return cmd
}

这个函数的作用是创建create命令，添加create命令flag，创建create命令子命令。以及create命令运行代码。

func (f *RecordFlags) AddFlags(cmd *cobra.Command) {
	if f == nil {
		return
	}

	if f.Record != nil {
		cmd.Flags().BoolVar(f.Record, "record", *f.Record, "Record current kubectl command in the resource annotation. If set to false, do not record the command. If set to true, record the command. If not set, default to updating the existing annotation value only if one already exists.")
	}
}

为create命令添加record flag。

func AddFilenameOptionFlags(cmd *cobra.Command, options *resource.FilenameOptions, usage string) {
	AddJsonFilenameFlag(cmd.Flags(), &options.Filenames, "Filename, directory, or URL to files "+usage)
	AddKustomizeFlag(cmd.Flags(), &options.Kustomize)
	cmd.Flags().BoolVarP(&options.Recursive, "recursive", "R", options.Recursive, "Process the directory used in -f, --filename recursively. Useful when you want to manage related manifests organized within the same directory.")
}

为create命令添加-f，-k，-r flag

func AddApplyAnnotationFlags(cmd *cobra.Command) {
	cmd.Flags().Bool(ApplyAnnotationsFlag, false, "If true, the configuration of current object will be saved in its annotation. Otherwise, the annotation will be unchanged. This flag is useful when you want to perform kubectl apply on this object in the future.")
}

为create命令添加save-config flag

func AddDryRunFlag(cmd *cobra.Command) {
	cmd.Flags().Bool("dry-run", false, "If true, only print the object that would be sent, without sending it.")
}

为create命令添加dry-run flag

func (f *PrintFlags) AddFlags(cmd *cobra.Command) {
	f.JSONYamlPrintFlags.AddFlags(cmd)
	f.NamePrintFlags.AddFlags(cmd)
	f.TemplatePrinterFlags.AddFlags(cmd)

	if f.OutputFormat != nil {
		cmd.Flags().StringVarP(f.OutputFormat, "output", "o", *f.OutputFormat, fmt.Sprintf("Output format. One of: %s.", strings.Join(f.AllowedFormats(), "|")))
		if f.OutputFlagSpecified == nil {
			f.OutputFlagSpecified = func() bool {
				return cmd.Flag("output").Changed
			}
		}
	}
}

为create命令添加output flag

cmdutil.CheckErr(o.Complete(f, cmd))
			cmdutil.CheckErr(o.ValidateArgs(cmd, args))
			cmdutil.CheckErr(o.RunCreate(f, cmd))

complete函数的作用是为命令执行做些准备工作，validateArgs函数的作用是校验参数，runCreate函数的作用是运行命令逻辑。

CheckErr函数的作用是处理错误。

func checkErr(err error, handleErr func(string, int)) {
	// unwrap aggregates of 1
	if agg, ok := err.(utilerrors.Aggregate); ok && len(agg.Errors()) == 1 {
		err = agg.Errors()[0]
	}

	if err == nil {
		return
	}

	switch {
	case err == ErrExit:
		handleErr("", DefaultErrorExitCode)
	case kerrors.IsInvalid(err):
		details := err.(*kerrors.StatusError).Status().Details
		s := fmt.Sprintf("The %s %q is invalid", details.Kind, details.Name)
		if len(details.Kind) == 0 && len(details.Name) == 0 {
			s = "The request is invalid"
		}
		if len(details.Causes) > 0 {
			errs := statusCausesToAggrError(details.Causes)
			handleErr(MultilineError(s+": ", errs), DefaultErrorExitCode)
		} else {
			handleErr(s, DefaultErrorExitCode)
		}
	case clientcmd.IsConfigurationInvalid(err):
		handleErr(MultilineError("Error in configuration: ", err), DefaultErrorExitCode)
	default:
		switch err := err.(type) {
		case *meta.NoResourceMatchError:
			switch {
			case len(err.PartialResource.Group) > 0 && len(err.PartialResource.Version) > 0:
				handleErr(fmt.Sprintf("the server doesn't have a resource type %q in group %q and version %q", err.PartialResource.Resource, err.PartialResource.Group, err.PartialResource.Version), DefaultErrorExitCode)
			case len(err.PartialResource.Group) > 0:
				handleErr(fmt.Sprintf("the server doesn't have a resource type %q in group %q", err.PartialResource.Resource, err.PartialResource.Group), DefaultErrorExitCode)
			case len(err.PartialResource.Version) > 0:
				handleErr(fmt.Sprintf("the server doesn't have a resource type %q in version %q", err.PartialResource.Resource, err.PartialResource.Version), DefaultErrorExitCode)
			default:
				handleErr(fmt.Sprintf("the server doesn't have a resource type %q", err.PartialResource.Resource), DefaultErrorExitCode)
			}
		case utilerrors.Aggregate:
			handleErr(MultipleErrors(``, err.Errors()), DefaultErrorExitCode)
		case utilexec.ExitError:
			handleErr(err.Error(), err.ExitStatus())
		default: // for any other error type
			msg, ok := StandardErrorMessage(err)
			if !ok {
				msg = err.Error()
				if !strings.HasPrefix(msg, "error: ") {
					msg = fmt.Sprintf("error: %s", msg)
				}
			}
			handleErr(msg, DefaultErrorExitCode)
		}
	}
}

分错误类型处理错误，错误类型有，

ErrExit，kerrors.IsInvalid(err)，clientcmd.IsConfigurationInvalid(err)，

*meta.NoResourceMatchError，utilerrors.Aggregate，utilexec.ExitError，default

func fatal(msg string, code int) {
	if klog.V(2) {
		klog.FatalDepth(2, msg)
	}
	if len(msg) > 0 {
		// add newline if needed
		if !strings.HasSuffix(msg, "\n") {
			msg += "\n"
		}
		fmt.Fprint(os.Stderr, msg)
	}
	os.Exit(code)
}

默认handleErr函数

func (o *CreateOptions) Complete(f cmdutil.Factory, cmd *cobra.Command) error {
	var err error
	o.RecordFlags.Complete(cmd)
	o.Recorder, err = o.RecordFlags.ToRecorder()
	if err != nil {
		return err
	}

	o.DryRun = cmdutil.GetDryRunFlag(cmd)

	if o.DryRun {
		o.PrintFlags.Complete("%s (dry run)")
	}
	printer, err := o.PrintFlags.ToPrinter()
	if err != nil {
		return err
	}

	o.PrintObj = func(obj kruntime.Object) error {
		return printer.PrintObj(obj, o.Out)
	}

	return nil
}

complete函数，

o.RecordFlags.Complete(cmd)准备record的cause

o.Recorder, err = o.RecordFlags.ToRecorder()：把record flag 转换为recorder

if o.DryRun {
   o.PrintFlags.Complete("%s (dry run)")
}如果执行了dry-run flag则准备print数据

printer, err := o.PrintFlags.ToPrinter()把print参数转换为printer对象

o.PrintObj = func(obj kruntime.Object) error {
   return printer.PrintObj(obj, o.Out)
}赋值printObj函数

func (f *RecordFlags) Complete(cmd *cobra.Command) error {
	if f == nil {
		return nil
	}

	f.changeCause = parseCommandArguments(cmd)
	return nil
}

recordflag的complete函数，赋值change cause

func (f *RecordFlags) ToRecorder() (Recorder, error) {
	if f == nil {
		return NoopRecorder{}, nil
	}

	shouldRecord := false
	if f.Record != nil {
		shouldRecord = *f.Record
	}

	// if flag was explicitly set to false by the user,
	// do not record
	if !shouldRecord {
		return NoopRecorder{}, nil
	}

	return &ChangeCauseRecorder{
		changeCause: f.changeCause,
	}, nil
}

record flag 转recorder，如果没有执行record flag 或record Flag为空则为NoopRecorder，否则为ChangeCauseRecorder

func (f *PrintFlags) ToPrinter() (printers.ResourcePrinter, error) {
	outputFormat := ""
	if f.OutputFormat != nil {
		outputFormat = *f.OutputFormat
	}
	// For backwards compatibility we want to support a --template argument given, even when no --output format is provided.
	// If no explicit output format has been provided via the --output flag, fallback
	// to honoring the --template argument.
	templateFlagSpecified := f.TemplatePrinterFlags != nil &&
		f.TemplatePrinterFlags.TemplateArgument != nil &&
		len(*f.TemplatePrinterFlags.TemplateArgument) > 0
	outputFlagSpecified := f.OutputFlagSpecified != nil && f.OutputFlagSpecified()
	if templateFlagSpecified && !outputFlagSpecified {
		outputFormat = "go-template"
	}

	if f.JSONYamlPrintFlags != nil {
		if p, err := f.JSONYamlPrintFlags.ToPrinter(outputFormat); !IsNoCompatiblePrinterError(err) {
			return f.TypeSetterPrinter.WrapToPrinter(p, err)
		}
	}

	if f.NamePrintFlags != nil {
		if p, err := f.NamePrintFlags.ToPrinter(outputFormat); !IsNoCompatiblePrinterError(err) {
			return f.TypeSetterPrinter.WrapToPrinter(p, err)
		}
	}

	if f.TemplatePrinterFlags != nil {
		if p, err := f.TemplatePrinterFlags.ToPrinter(outputFormat); !IsNoCompatiblePrinterError(err) {
			return f.TypeSetterPrinter.WrapToPrinter(p, err)
		}
	}

	return nil, NoCompatiblePrinterError{OutputFormat: f.OutputFormat, AllowedFormats: f.AllowedFormats()}
}

根据outputFormat依次转为，

f.JSONYamlPrintFlags.ToPrinter(outputFormat)，f.NamePrintFlags.ToPrinter(outputFormat)，f.TemplatePrinterFlags.ToPrinter(outputFormat)并用TypeSetterPrinter包装

func (o *CreateOptions) ValidateArgs(cmd *cobra.Command, args []string) error {
	if len(args) != 0 {
		return cmdutil.UsageErrorf(cmd, "Unexpected args: %v", args)
	}
	if len(o.Raw) > 0 {
		if o.EditBeforeCreate {
			return cmdutil.UsageErrorf(cmd, "--raw and --edit are mutually exclusive")
		}
		if len(o.FilenameOptions.Filenames) != 1 {
			return cmdutil.UsageErrorf(cmd, "--raw can only use a single local file or stdin")
		}
		if strings.Index(o.FilenameOptions.Filenames[0], "http://") == 0 || strings.Index(o.FilenameOptions.Filenames[0], "https://") == 0 {
			return cmdutil.UsageErrorf(cmd, "--raw cannot read from a url")
		}
		if o.FilenameOptions.Recursive {
			return cmdutil.UsageErrorf(cmd, "--raw and --recursive are mutually exclusive")
		}
		if len(o.Selector) > 0 {
			return cmdutil.UsageErrorf(cmd, "--raw and --selector (-l) are mutually exclusive")
		}
		if len(cmdutil.GetFlagString(cmd, "output")) > 0 {
			return cmdutil.UsageErrorf(cmd, "--raw and --output are mutually exclusive")
		}
		if _, err := url.ParseRequestURI(o.Raw); err != nil {
			return cmdutil.UsageErrorf(cmd, "--raw must be a valid URL path: %v", err)
		}
	}

	return nil
}

验证参数

func (o *CreateOptions) RunCreate(f cmdutil.Factory, cmd *cobra.Command) error {
	// raw only makes sense for a single file resource multiple objects aren't likely to do what you want.
	// the validator enforces this, so
	if len(o.Raw) > 0 {
		restClient, err := f.RESTClient()
		if err != nil {
			return err
		}
		return rawhttp.RawPost(restClient, o.IOStreams, o.Raw, o.FilenameOptions.Filenames[0])
	}

	if o.EditBeforeCreate {
		return RunEditOnCreate(f, o.PrintFlags, o.RecordFlags, o.IOStreams, cmd, &o.FilenameOptions)
	}
	schema, err := f.Validator(cmdutil.GetFlagBool(cmd, "validate"))
	if err != nil {
		return err
	}

	cmdNamespace, enforceNamespace, err := f.ToRawKubeConfigLoader().Namespace()
	if err != nil {
		return err
	}

	r := f.NewBuilder().
		Unstructured().
		Schema(schema).
		ContinueOnError().
		NamespaceParam(cmdNamespace).DefaultNamespace().
		FilenameParam(enforceNamespace, &o.FilenameOptions).
		LabelSelectorParam(o.Selector).
		Flatten().
		Do()
	err = r.Err()
	if err != nil {
		return err
	}

	count := 0
	err = r.Visit(func(info *resource.Info, err error) error {
		if err != nil {
			return err
		}
		if err := util.CreateOrUpdateAnnotation(cmdutil.GetFlagBool(cmd, cmdutil.ApplyAnnotationsFlag), info.Object, scheme.DefaultJSONEncoder()); err != nil {
			return cmdutil.AddSourceToErr("creating", info.Source, err)
		}

		if err := o.Recorder.Record(info.Object); err != nil {
			klog.V(4).Infof("error recording current command: %v", err)
		}

		if !o.DryRun {
			if err := createAndRefresh(info); err != nil {
				return cmdutil.AddSourceToErr("creating", info.Source, err)
			}
		}

		count++

		return o.PrintObj(info.Object)
	})
	if err != nil {
		return err
	}
	if count == 0 {
		return fmt.Errorf("no objects passed to create")
	}
	return nil
}

分三种情况，分别是指定，--raw，--edit和没有指定上面两个参数的执行逻辑。

当指定--raw则运行rawhttp.RawPost

如果指定--edir则运行RunEditOnCreate

否则运行下面逻辑。

schema, err := f.Validator(cmdutil.GetFlagBool(cmd, "validate"))构造资源校验schema

cmdNamespace, enforceNamespace, err := f.ToRawKubeConfigLoader().Namespace()获取namespace和强制namespace

r := f.NewBuilder().
   Unstructured().
   Schema(schema).
   ContinueOnError().
   NamespaceParam(cmdNamespace).DefaultNamespace().
   FilenameParam(enforceNamespace, &o.FilenameOptions).
   LabelSelectorParam(o.Selector).
   Flatten().
   Do()构造info对象

err = r.Visit(func(info *resource.Info, err error) error {
   if err != nil {
      return err
   }
   if err := util.CreateOrUpdateAnnotation(cmdutil.GetFlagBool(cmd, cmdutil.ApplyAnnotationsFlag), info.Object, scheme.DefaultJSONEncoder()); err != nil {
      return cmdutil.AddSourceToErr("creating", info.Source, err)
   }

   if err := o.Recorder.Record(info.Object); err != nil {
      klog.V(4).Infof("error recording current command: %v", err)
   }

   if !o.DryRun {
      if err := createAndRefresh(info); err != nil {
         return cmdutil.AddSourceToErr("creating", info.Source, err)
      }
   }

   count++

   return o.PrintObj(info.Object)
})

访问info对象。进行处理。

if err := util.CreateOrUpdateAnnotation(cmdutil.GetFlagBool(cmd, cmdutil.ApplyAnnotationsFlag), info.Object, scheme.DefaultJSONEncoder()); err != nil {
   return cmdutil.AddSourceToErr("creating", info.Source, err)
}如果指定save-config flag则添加相应注解

if err := o.Recorder.Record(info.Object); err != nil {
   klog.V(4).Infof("error recording current command: %v", err)
}如果指定record flag则添加相应注解

if !o.DryRun {
   if err := createAndRefresh(info); err != nil {
      return cmdutil.AddSourceToErr("creating", info.Source, err)
   }
}

如果没有指定dry-run，则创建资源并刷新

o.PrintObj(info.Object)打印结果

func CreateOrUpdateAnnotation(createAnnotation bool, obj runtime.Object, codec runtime.Encoder) error {
	if createAnnotation {
		return CreateApplyAnnotation(obj, codec)
	}
	return updateApplyAnnotation(obj, codec)
}

创建或更新注解

func RunEditOnCreate(f cmdutil.Factory, printFlags *genericclioptions.PrintFlags, recordFlags *genericclioptions.RecordFlags, ioStreams genericclioptions.IOStreams, cmd *cobra.Command, options *resource.FilenameOptions) error {
	editOptions := editor.NewEditOptions(editor.EditBeforeCreateMode, ioStreams)
	editOptions.FilenameOptions = *options
	editOptions.ValidateOptions = cmdutil.ValidateOptions{
		EnableValidation: cmdutil.GetFlagBool(cmd, "validate"),
	}
	editOptions.PrintFlags = printFlags
	editOptions.ApplyAnnotation = cmdutil.GetFlagBool(cmd, cmdutil.ApplyAnnotationsFlag)
	editOptions.RecordFlags = recordFlags

	err := editOptions.Complete(f, []string{}, cmd)
	if err != nil {
		return err
	}
	return editOptions.Run()
}

如果指定了edit flag则进入创建时编辑函数。把create option转换为edit option，然后运行编辑命令。