k8s源码分析4-create命令执行流程

本节重点总结 :

1. newCmdCreate 调用cobra的Run函数
2. 调用RunCreate构建resourceBuilder对象
3. 调用visit方法创建资源
4. 底层使用resetclient 和k8s-api通信

架构图

create的流程 NewCmdCreate

• 代码入口 D:\go_path\src\github.com\kubernetes\kubernetes\staging\src\k8s.io\kubectl\pkg\cmd\create\create.go

创建Create选项对象

o := NewCreateOptions(ioStreams)

初始化cmd

	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))
		},
	}

设置选项

• 具体绑定到o的各个字段上

	// 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.")
	cmdutil.AddFieldManagerFlagVar(cmd, &o.fieldManager, "kubectl-create")

	o.PrintFlags.AddFlags(cmd)

绑定创建子命令

	// 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))
	cmd.AddCommand(NewCmdCreateIngress(f, ioStreams))

核心的cmd.Run函数

校验文件参数

			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
			}

完善并填充所需字段

cmdutil.CheckErr(o.Complete(f, cmd))

校验参数

cmdutil.CheckErr(o.ValidateArgs(cmd, args))

核心的RunCreate

• 位置 D:\go_path\src\github.com\kubernetes\kubernetes\staging\src\k8s.io\kubectl\pkg\cmd\create\create.go

cmdutil.CheckErr(o.RunCreate(f, cmd))

如果配置了apiserver的raw-uri就直接发送请求

	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])
	}

如果配置了创建前 edit就执行 RunEditOnCreate

	if o.EditBeforeCreate {
		return RunEditOnCreate(f, o.PrintFlags, o.RecordFlags, o.IOStreams, cmd, &o.FilenameOptions, o.fieldManager)
	}

根据配置中的validate决定是否开启validate

• --validate=true: 使用一种模式校验一下配置，模式是true的
• 意思是避免yaml中配置错了

	schema, err := f.Validator(cmdutil.GetFlagBool(cmd, "validate"))
	if err != nil {
		return err
	}

根据命令行获取namespace

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

构建builder对象

	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
	}

FilenameParam读取配置文件

• 除了支持简单的本地文件，也支持标准输入和http/https协议访问的文件，保存为Visitor
• 代码位置 D:\go_path\src\github.com\kubernetes\kubernetes\staging\src\k8s.io\cli-runtime\pkg\resource\builder.go

func (b *Builder) FilenameParam(enforceNamespace bool, filenameOptions *FilenameOptions) *Builder {
	if errs := filenameOptions.validate(); len(errs) > 0 {
		b.errs = append(b.errs, errs...)
		return b
	}
	recursive := filenameOptions.Recursive
	paths := filenameOptions.Filenames
	for _, s := range paths {
		switch {
		case s == "-":
			b.Stdin()
		case strings.Index(s, "http://") == 0 || strings.Index(s, "https://") == 0:
			url, err := url.Parse(s)
			if err != nil {
				b.errs = append(b.errs, fmt.Errorf("the URL passed to filename %q is not valid: %v", s, err))
				continue
			}
			b.URL(defaultHttpGetAttempts, url)
		default:
			if !recursive {
				b.singleItemImplied = true
			}
			b.Path(recursive, s)
		}
	}
	if filenameOptions.Kustomize != "" {
		b.paths = append(
			b.paths,
			&KustomizeVisitor{
				mapper:  b.mapper,
				dirPath: filenameOptions.Kustomize,
				schema:  b.schema,
				fSys:    filesys.MakeFsOnDisk(),
			})
	}

	if enforceNamespace {
		b.RequireNamespace()
	}

	return b
}

调用visit函数创建资源

	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.DryRunStrategy != cmdutil.DryRunClient {
			if o.DryRunStrategy == cmdutil.DryRunServer {
				if err := o.DryRunVerifier.HasSupport(info.Mapping.GroupVersionKind); err != nil {
					return cmdutil.AddSourceToErr("creating", info.Source, err)
				}
			}
			obj, err := resource.
				NewHelper(info.Client, info.Mapping).
				DryRun(o.DryRunStrategy == cmdutil.DryRunServer).
				WithFieldManager(o.fieldManager).
				Create(info.Namespace, true, info.Object)
			if err != nil {
				return cmdutil.AddSourceToErr("creating", info.Source, err)
			}
			info.Refresh(obj, true)
		}

• Create函数追踪底层调用 createResource创建资源
• 位置 D:\go_path\src\github.com\kubernetes\kubernetes\staging\src\k8s.io\cli-runtime\pkg\resource\helper.go

func (m *Helper) createResource(c RESTClient, resource, namespace string, obj runtime.Object, options *metav1.CreateOptions) (runtime.Object, error) {
	return c.Post().
		NamespaceIfScoped(namespace, m.NamespaceScoped).
		Resource(resource).
		VersionedParams(options, metav1.ParameterCodec).
		Body(obj).
		Do(context.TODO()).
		Get()
}

• 底层使用 restfulclient .post
• D:\go_path\src\github.com\kubernetes\kubernetes\staging\src\k8s.io\cli-runtime\pkg\resource\interfaces.go

type RESTClient interface {
	Get() *rest.Request
	Post() *rest.Request
	Patch(types.PatchType) *rest.Request
	Delete() *rest.Request
	Put() *rest.Request
}

本节重点总结 :

1. newCmdCreate 调用cobra的Run函数
2. 调用RunCreate构建resourceBuilder对象
3. 调用visit方法创建资源
4. 底层使用resetclient 和k8s-api通信