client-go之dynamic包(上篇)源码分析

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dynamic包

用于动态生成informer/lister/client等

interface.go

  • 接口.go 
    // ResourceInterface的工厂模式，方法Resource可以获取对应gvr的ResourceInterface接口
type Interface interface {
	Resource(resource schema.GroupVersionResource) NamespaceableResourceInterface
}
// 操作对应obj的接口
type ResourceInterface interface {
	Create(ctx context.Context, obj *unstructured.Unstructured, options metav1.CreateOptions, subresources ...string) (*unstructured.Unstructured, error)
	Update(ctx context.Context, obj *unstructured.Unstructured, options metav1.UpdateOptions, subresources ...string) (*unstructured.Unstructured, error)
	UpdateStatus(ctx context.Context, obj *unstructured.Unstructured, options metav1.UpdateOptions) (*unstructured.Unstructured, error)
	Delete(ctx context.Context, name string, options metav1.DeleteOptions, subresources ...string) error
	DeleteCollection(ctx context.Context, options metav1.DeleteOptions, listOptions metav1.ListOptions) error
	Get(ctx context.Context, name string, options metav1.GetOptions, subresources ...string) (*unstructured.Unstructured, error)
	List(ctx context.Context, opts metav1.ListOptions) (*unstructured.UnstructuredList, error)
	Watch(ctx context.Context, opts metav1.ListOptions) (watch.Interface, error)
	Patch(ctx context.Context, name string, pt types.PatchType, data []byte, options metav1.PatchOptions, subresources ...string) (*unstructured.Unstructured, error)
}
// 限定了namespace的ResourceInterface
type NamespaceableResourceInterface interface {
	Namespace(string) ResourceInterface
	ResourceInterface
}

simple.go 对于上面提到的接口的简单实现

  • 函数 
    // ConfigFor 返回提供的配置的副本，并设置了适当的动态客户端默认值。
func ConfigFor(inConfig *rest.Config) *rest.Config {
  // 复制参数配置文件
	config := rest.CopyConfig(inConfig)
  // 设置默认属性
	config.AcceptContentTypes = "application/json"
	config.ContentType = "application/json"
	config.NegotiatedSerializer = basicNegotiatedSerializer{}
	if config.UserAgent == "" {
		config.UserAgent = rest.DefaultKubernetesUserAgent()
	}
	return config
}

// NewForConfig 创建新的动态客户端或返回错误。
func NewForConfig(inConfig *rest.Config) (Interface, error) {
  // 复制并设置默认的属性
	config := ConfigFor(inConfig)
	// 用于序列化选项
	config.GroupVersion = &schema.GroupVersion{}
	config.APIPath = "/if-you-see-this-search-for-the-break"
  // 获取包装了http.client的client，操作obj，后面章节讲解
	restClient, err := rest.RESTClientFor(config)
	if err != nil {
		return nil, err
	}
	return &dynamicClient{client: restClient}, nil
}
  • 结构体 
    // rest.RESTClient（操作obj的具体执行client）的包装结构体
type dynamicClient struct {
	client *rest.RESTClient
}
// 操作对应obj的接口
type ResourceInterface interface {
	Create(ctx context.Context, obj *unstructured.Unstructured, options metav1.CreateOptions, subresources ...string) (*unstructured.Unstructured, error)
	Update(ctx context.Context, obj *unstructured.Unstructured, options metav1.UpdateOptions, subresources ...string) (*unstructured.Unstructured, error)
	UpdateStatus(ctx context.Context, obj *unstructured.Unstructured, options metav1.UpdateOptions) (*unstructured.Unstructured, error)
	Delete(ctx context.Context, name string, options metav1.DeleteOptions, subresources ...string) error
	DeleteCollection(ctx context.Context, options metav1.DeleteOptions, listOptions metav1.ListOptions) error
	Get(ctx context.Context, name string, options metav1.GetOptions, subresources ...string) (*unstructured.Unstructured, error)
	List(ctx context.Context, opts metav1.ListOptions) (*unstructured.UnstructuredList, error)
	Watch(ctx context.Context, opts metav1.ListOptions) (watch.Interface, error)
	Patch(ctx context.Context, name string, pt types.PatchType, data []byte, options metav1.PatchOptions, subresources ...string) (*unstructured.Unstructured, error)
}
// 限定了namespace的ResourceInterface
type NamespaceableResourceInterface interface {
	Namespace(string) ResourceInterface
	ResourceInterface
}

// NamespaceableResourceInterface接口的实现
type dynamicResourceClient struct {
	client    *dynamicClient
	namespace string // 限定namespace
	resource  schema.GroupVersionResource // 限定gvr
}

// 实现Interface接口的Resource方法，获取操作资源的client
func (c *dynamicClient) Resource(resource schema.GroupVersionResource) NamespaceableResourceInterface {
	return &dynamicResourceClient{client: c, resource: resource}
}

// 实现了NamespaceableResourceInterface接口的Namespace方法
func (c *dynamicResourceClient) Namespace(ns string) ResourceInterface {
	ret := *c // 获取指针地址
	ret.namespace = ns // 修改对应地址的值
	return &ret // 返回指针地址对应的value
}

// 只分析create方法，其他方法类似
// 实现了ResourceInterface接口的Create方法，用来创建参数对应的obj
func (c *dynamicResourceClient) Create(ctx context.Context, obj *unstructured.Unstructured, opts metav1.CreateOptions, subresources ...string) (*unstructured.Unstructured, error) {
  // 把Unstructured obj（内部其实是map类型）转化为字节数组
	outBytes, err := runtime.Encode(unstructured.UnstructuredJSONScheme, obj)
	if err != nil {
		return nil, err
	}
	name := ""
  // 如果subresources不为空，这里会判定obj的name不为空
	if len(subresources) > 0 {
		accessor, err := meta.Accessor(obj)
		if err != nil {
			return nil, err
		}
		name = accessor.GetName()
		if len(name) == 0 {
			return nil, fmt.Errorf("name is required")
		}
	}
  
  // 如果name不为空，再创建时则使用该name，否则随机生成。（这里只是建立了tcp长链接和解码相应，具体的执行逻辑还是在k8s api-server中调用k8s api的etcd相关接口）
	result := c.client.client.
		Post().
		AbsPath(append(c.makeURLSegments(name), subresources...)...).
		Body(outBytes).
		SpecificallyVersionedParams(&opts, dynamicParameterCodec, versionV1).
		Do(ctx)
	if err := result.Error(); err != nil {
		return nil, err
	}
  // 返回原始结果（字节数组数据）
	retBytes, err := result.Raw()
	if err != nil {
		return nil, err
	}
  // 使用json编解码器  解码原始数据，得到一个Unstructured类型的数据
	uncastObj, err := runtime.Decode(unstructured.UnstructuredJSONScheme, retBytes)
	if err != nil {
		return nil, err
	}
	return uncastObj.(*unstructured.Unstructured), nil
}

scheme.go 实现kubernetes/apimachinery的序列化和编解码（ListOptions/GetOptions/DeleteOptions/CreateOptions/UpdateOptions/PatchOptions），供上面ResourceClient使用。

  • 变量 
    // 暂时没有什么用途（估计是备用）
var watchScheme = runtime.NewScheme()
// 供basicNegotiatedSerializer来获取gvk/类型转化/创建obj
var basicScheme = runtime.NewScheme()
// 为上面ResourceClient删除操作的Options创建删除CodecFactory（编解码器工厂），提供Scheme参数
var deleteScheme = runtime.NewScheme()
// 为上面ResourceClient各种操作创建参数CodecFactory（编解码器工厂），提供Scheme参数
var parameterScheme = runtime.NewScheme()
// 创建删除CodecFactory（编解码器工厂）,编解码DeleteOptions对象
var deleteOptionsCodec = serializer.NewCodecFactory(deleteScheme)
// 创建参数CodecFactory（编解码器工厂）,编解码ListOptions/GetOptions/CreateOptions/UpdateOptions/PatchOptions对象，作为请求参数
var dynamicParameterCodec = runtime.NewParameterCodec(parameterScheme)
// 定义gv
var versionV1 = schema.GroupVersion{Version: "v1"}
// 添加ListOptions/GetOptions/DeleteOptions/CreateOptions/UpdateOptions/PatchOptions，初始化各个schema
func init() {
	metav1.AddToGroupVersion(watchScheme, versionV1)
	metav1.AddToGroupVersion(basicScheme, versionV1)
	metav1.AddToGroupVersion(parameterScheme, versionV1)
	metav1.AddToGroupVersion(deleteScheme, versionV1)
}
  • 结构体 
    // 实现了NegotiatedSerializer接口,根据content判断，以何种方式编解码obj
type basicNegotiatedSerializer struct{}

// 实现NegotiatedSerializer的SupportedMediaTypes方法,自定义可以处理的MediaType，并定义各种MediaType的Serializer
func (s basicNegotiatedSerializer) SupportedMediaTypes() []runtime.SerializerInfo {
	return []runtime.SerializerInfo{
		{
			MediaType:        "application/json",
			MediaTypeType:    "application",
			MediaTypeSubType: "json",
			EncodesAsText:    true,
			Serializer:       json.NewSerializer(json.DefaultMetaFactory, unstructuredCreater{basicScheme}, unstructuredTyper{basicScheme}, false),
			PrettySerializer: json.NewSerializer(json.DefaultMetaFactory, unstructuredCreater{basicScheme}, unstructuredTyper{basicScheme}, true),
			StreamSerializer: &runtime.StreamSerializerInfo{
				EncodesAsText: true,
				Serializer:    json.NewSerializer(json.DefaultMetaFactory, basicScheme, basicScheme, false),
				Framer:        json.Framer,
			},
		},
	}
}
// 实现NegotiatedSerializer的EncoderForVersion方法,获取一个版本化的Encoder（编码为指定版本）
func (s basicNegotiatedSerializer) EncoderForVersion(encoder runtime.Encoder, gv runtime.GroupVersioner) runtime.Encoder {
	return runtime.WithVersionEncoder{
		Version:     gv,
		Encoder:     encoder,
		ObjectTyper: unstructuredTyper{basicScheme},
	}
}

// 实现NegotiatedSerializer的DecoderToVersion方法, 获取原始的decoder
func (s basicNegotiatedSerializer) DecoderToVersion(decoder runtime.Decoder, gv runtime.GroupVersioner) runtime.Decoder {
	return decoder
}

// unstructuredCreater 包装了ObjectCreater（用于New一个gvk对应的obj），如果有err，那么和ObjectCreater的区别是返回了空的obj，而err为空
type unstructuredCreater struct {
	nested runtime.ObjectCreater
}

// 实现了ObjectCreater接口的New方法
func (c unstructuredCreater) New(kind schema.GroupVersionKind) (runtime.Object, error) {
	out, err := c.nested.New(kind)
	if err == nil {
		return out, nil
	}
  // 这里和ObjectCreater有区别，如果有err，那么和ObjectCreater的区别是返回了空的obj，而err为空
	out = &unstructured.Unstructured{}
	out.GetObjectKind().SetGroupVersionKind(kind)
	return out, nil
}

// unstructuredTyper 包装了ObjectTyper（用于获取obj对应的gvk列表），如果有err，那么和ObjectTyper的区别是会判断是否是Unstructured类型且obj对应的gvk是否为空
type unstructuredTyper struct {
	nested runtime.ObjectTyper
}

// 实现了ObjectTyper接口的ObjectKinds方法
func (t unstructuredTyper) ObjectKinds(obj runtime.Object) ([]schema.GroupVersionKind, bool, error) {
	kinds, unversioned, err := t.nested.ObjectKinds(obj)
	if err == nil {
		return kinds, unversioned, nil
	}
  // 判断obj是否是Unstructured类型且对应的gvk是否为空
	if _, ok := obj.(runtime.Unstructured); ok && !obj.GetObjectKind().GroupVersionKind().Empty() {
		return []schema.GroupVersionKind{obj.GetObjectKind().GroupVersionKind()}, false, nil
	}
	return nil, false, err
}
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