generic_config.md

API server 通用配置

在 CreateServerChain func 中分析 CreateKubeAPIServerConfig

kubeAPIServerConfig, serviceResolver, pluginInitializer, err := CreateKubeAPIServerConfig(completedOptions)
	

CreateKubeAPIServerConfig

• 文件： cmd/kube-apiserver/app/server.go

1. 创建和节点通讯的结构体 proxyTransport

proxyTransport := CreateProxyTransport()

http.transport 主要功能是缓存长连接

2. 创建通用配置 genericConfig

genericConfig, versionedInformers, serviceResolver, pluginInitializers, admissionPostStartHook, storageFactory, err := buildGenericConfig(s.ServerRunOptions, proxyTransport)
	if err != nil {
		return nil, nil, nil, err
	}

3. 大量 applyTo 并且有对应的 AddFlags 标记命令行参数， 同时创建 ETCD 存储 和 k8s clientset

    // 初始化config
    genericConfig = genericapiserver.NewConfig(legacyscheme.Codecs)
	
	if lastErr = s.GenericServerRunOptions.ApplyTo(genericConfig); lastErr != nil {
		return
	}

	if lastErr = s.SecureServing.ApplyTo(&genericConfig.SecureServing, &genericConfig.LoopbackClientConfig); lastErr != nil {
		return
	}
	if lastErr = s.Features.ApplyTo(genericConfig); lastErr != nil {
		return
	}
	if lastErr = s.APIEnablement.ApplyTo(genericConfig, controlplane.DefaultAPIResourceConfigSource(), legacyscheme.Scheme); lastErr != nil {
		return
	}
	if lastErr = s.EgressSelector.ApplyTo(genericConfig); lastErr != nil {
		return
	}
	if utilfeature.DefaultFeatureGate.Enabled(genericfeatures.APIServerTracing) {
		if lastErr = s.Traces.ApplyTo(genericConfig.EgressSelector, genericConfig); lastErr != nil {
			return
		}
	}
	
	...
	
	if lastErr = s.Etcd.Complete(genericConfig.StorageObjectCountTracker, genericConfig.DrainedNotify(), genericConfig.AddPostStartHook); lastErr != nil {
		return
	}

	// Etcd 存储
	storageFactoryConfig := kubeapiserver.NewStorageFactoryConfig()
	storageFactoryConfig.APIResourceConfig = genericConfig.MergedResourceConfig
	storageFactory, lastErr = storageFactoryConfig.Complete(s.Etcd).New()
	if lastErr != nil {
		return
	}
	if lastErr = s.Etcd.ApplyWithStorageFactoryTo(storageFactory, genericConfig); lastErr != nil {
		return
	}

	// protobufs 禁止内部压缩功能
	
	// Use protobufs for self-communication.
	// Since not every generic apiserver has to support protobufs, we
	// cannot default to it in generic apiserver and need to explicitly
	// set it in kube-apiserver.
	genericConfig.LoopbackClientConfig.ContentConfig.ContentType = "application/vnd.kubernetes.protobuf"
	// Disable compression for self-communication, since we are going to be
	// on a fast local network
	genericConfig.LoopbackClientConfig.DisableCompression = true

	// 创建 clientset
	kubeClientConfig := genericConfig.LoopbackClientConfig
	clientgoExternalClient, err := clientgoclientset.NewForConfig(kubeClientConfig)
	if err != nil {
		lastErr = fmt.Errorf("failed to create real external clientset: %v", err)
		return
	}
	versionedInformers = clientgoinformers.NewSharedInformerFactory(clientgoExternalClient, 10*time.Minute)

	// 认证
	// Authentication.ApplyTo requires already applied OpenAPIConfig and EgressSelector if present
	if lastErr = s.Authentication.ApplyTo(&genericConfig.Authentication, genericConfig.SecureServing, genericConfig.EgressSelector, genericConfig.OpenAPIConfig, genericConfig.OpenAPIV3Config, clientgoExternalClient, versionedInformers); lastErr != nil {
	return
	}

	// 授权
	genericConfig.Authorization.Authorizer, genericConfig.RuleResolver, err = BuildAuthorizer(s, genericConfig.EgressSelector, versionedInformers)
	if err != nil {
	lastErr = fmt.Errorf("invalid authorization config: %v", err)
	return
	}

	// 审计
	lastErr = s.Audit.ApplyTo(genericConfig)
	if lastErr != nil {
		return
	}
	// 准入控制
	admissionConfig := &kubeapiserveradmission.Config{
		ExternalInformers:    versionedInformers,
		LoopbackClientConfig: genericConfig.LoopbackClientConfig,
		CloudConfigFile:      s.CloudProvider.CloudConfigFile,
	}
	serviceResolver = buildServiceResolver(s.EnableAggregatorRouting, genericConfig.LoopbackClientConfig.Host, versionedInformers)
	schemaResolver := resolver.NewDefinitionsSchemaResolver(k8sscheme.Scheme, genericConfig.OpenAPIConfig.GetDefinitions)
	pluginInitializers, admissionPostStartHook, err = admissionConfig.New(proxyTransport, genericConfig.EgressSelector, serviceResolver, genericConfig.TracerProvider, schemaResolver)
	if err != nil {
		lastErr = fmt.Errorf("failed to create admission plugin initializer: %v", err)
		return
	}

	err = s.Admission.ApplyTo(
		genericConfig,
		versionedInformers,
		kubeClientConfig,
		utilfeature.DefaultFeatureGate,
		pluginInitializers...)
	if err != nil {
		lastErr = fmt.Errorf("failed to initialize admission: %v", err)
		return
	}
    ...

	return