摘要：它包括一組和一個對象，使用進行請求派發。流程基本就是這樣，接著我們直接進入接口看實現拼裝然后填充并返回一個對象創建一個這個是關鍵，會對各種進行注冊增加一個的將該加入到前兩個調用函數比較簡單，這里不進行介紹了。

Kubernetes v1.5.0

go-restful是用于構建REST-style web服務的golang包。
它是出現時因為一個javaer在golang中沒找到順手的REST-based服務構建包，所以就按照他在java里常用的JAX-RS的設計，在golang中造了一個輪子。

1.Route:
路由包含兩種，一種是標準JSR311接口規范的實現RouterJSR311,一種是快速路由CurlyRouter。
CurlyRouter支持正則表達式和動態參數，相比RouterJSR11更加輕量級，apiserver中使用的就是這種路由。
一種Route的設定包含：請求方法(http Method)，請求路徑(URL Path),輸入輸出類型(JSON/YAML)以及對應的回掉函數restful.RouteFunction，響應內容類型(Accept)等。

2.WebService：
WebService邏輯上是Route的集合，功能上主要是為一組Route統一設置包括root path,請求響應的數據類型等一些通用的屬性。
需要注意的是，WebService必須加入到Container中才能生效。

func (g *APIGroupVersion) InstallREST(container *restful.Container) error {
    installer := g.newInstaller()
    ws := installer.NewWebService()
    。。。
    container.Add(ws)
    return utilerrors.NewAggregate(registrationErrors)
}

上面是k8s的REST注冊接口，也調用了Container.Add(ws)，才能讓這個ws生效。

3.Container：
Container邏輯上是WebService的集合，功能上可以實現多終端的效果。
它包括一組restful.WebService和一個http.ServeMux對象，使用RouteSelector進行請求派發。
例如，下面代碼中創建了兩個Container，分別在不同的port上提供服務。
該代碼是go-restful的example：

package main

import (
    "github.com/emicklei/go-restful"
    "io"
    "log"
    "net/http"
)

func main() {
    ws := new(restful.WebService)
    ws.Route(ws.GET("/hello").To(hello))
    // ws被添加到默認的container restful.DefaultContainer中
    restful.Add(ws)
    go func() {
        // restful.DefaultContainer監聽在端口8080上
        http.ListenAndServe(":8080", nil)
    }()

    container2 := restful.NewContainer()
    ws2 := new(restful.WebService)
    ws2.Route(ws2.GET("/hello").To(hello2))
    // ws2被添加到container2中
    container2.Add(ws2)
    // container2中監聽端口8081
    server := &http.Server{Addr: ":8081", Handler: container2}
    log.Fatal(server.ListenAndServe())
}

func hello(req *restful.Request, resp *restful.Response) {
    io.WriteString(resp, "default world")
}

func hello2(req *restful.Request, resp *restful.Response) {
    io.WriteString(resp, "second world")
}

4.Filter:
Filter用于動態的攔截請求和響應，類似于放置在相應組件前的鉤子，在相應組件功能運行前捕獲請求或者響應，主要用于記錄log，驗證，重定向等功能。
go-restful中有三種類型的Filter：

Container Filter:
運行在Container中所有的WebService執行之前。

// install a (global) filter for the default container (processed before any webservice)
restful.Filter(globalLogging)

WebService Filter：
運行在WebService中所有的Route執行之前。

// install a webservice filter (processed before any route)
ws.Filter(webserviceLogging).Filter(measureTime)

Route Filter:
運行在調用Route綁定的方法之前。

// install 2 chained route filters (processed before calling findUser)
ws.Route(ws.GET("/{user-id}").Filter(routeLogging).Filter(NewCountFilter().routeCounter).To(findUser))

拿用官方提供的例子：

package main

import (
    "github.com/emicklei/go-restful"
    "log"
    "net/http"
)

type User struct {
    Id, Name string
}

type UserResource struct {
    // normally one would use DAO (data access object)
    users map[string]User
}

func (u UserResource) Register(container *restful.Container) {
      // 創建新的WebService
    ws := new(restful.WebService)
  
      // 設定WebService對應的路徑("/users")和支持的MIME類型(restful.MIME_XML/ restful.MIME_JSON)
    ws.
        Path("/users").
        Consumes(restful.MIME_XML, restful.MIME_JSON).
        Produces(restful.MIME_JSON, restful.MIME_XML) // you can specify this per route as well

      // 添加路由： GET /{user-id} --> u.findUser
    ws.Route(ws.GET("/{user-id}").To(u.findUser))
  
      // 添加路由： POST / --> u.updateUser
    ws.Route(ws.POST("").To(u.updateUser))
  
      // 添加路由： PUT /{user-id} --> u.createUser
    ws.Route(ws.PUT("/{user-id}").To(u.createUser))
  
      // 添加路由： DELETE /{user-id} --> u.removeUser
    ws.Route(ws.DELETE("/{user-id}").To(u.removeUser))

      // 將初始化好的WebService添加到Container中
    container.Add(ws)
}

// GET http://localhost:8080/users/1
//
func (u UserResource) findUser(request *restful.Request, response *restful.Response) {
    id := request.PathParameter("user-id")
    usr := u.users[id]
    if len(usr.Id) == 0 {
        response.AddHeader("Content-Type", "text/plain")
        response.WriteErrorString(http.StatusNotFound, "User could not be found.")
    } else {
        response.WriteEntity(usr)
    }
}

// POST http://localhost:8080/users
// 1Melissa Raspberry
//
func (u *UserResource) updateUser(request *restful.Request, response *restful.Response) {
    usr := new(User)
    err := request.ReadEntity(&usr)
    if err == nil {
        u.users[usr.Id] = *usr
        response.WriteEntity(usr)
    } else {
        response.AddHeader("Content-Type", "text/plain")
        response.WriteErrorString(http.StatusInternalServerError, err.Error())
    }
}

// PUT http://localhost:8080/users/1
// 1Melissa
//
func (u *UserResource) createUser(request *restful.Request, response *restful.Response) {
    usr := User{Id: request.PathParameter("user-id")}
    err := request.ReadEntity(&usr)
    if err == nil {
        u.users[usr.Id] = usr
        response.WriteHeader(http.StatusCreated)
        response.WriteEntity(usr)
    } else {
        response.AddHeader("Content-Type", "text/plain")
        response.WriteErrorString(http.StatusInternalServerError, err.Error())
    }
}

// DELETE http://localhost:8080/users/1
//
func (u *UserResource) removeUser(request *restful.Request, response *restful.Response) {
    id := request.PathParameter("user-id")
    delete(u.users, id)
}

func main() {
      // 創建一個空的Container
    wsContainer := restful.NewContainer()
  
    // 設定路由為CurlyRouter(快速路由)
    wsContainer.Router(restful.CurlyRouter{})
  
      // 創建自定義的Resource Handle(此處為UserResource)
    u := UserResource{map[string]User{}}
  
      // 創建WebService，并將WebService加入到Container中
    u.Register(wsContainer)

    log.Printf("start listening on localhost:8080")
    server := &http.Server{Addr: ":8080", Handler: wsContainer}
      
      // 啟動服務
    log.Fatal(server.ListenAndServe())
}

上面的示例代碼構建RESTful服務，分為幾個步驟，apiServer也是類似：
1.創建Container
2.配置Container屬性：ServeMux/Router type等
3.創建自定義的Resource Handle，實現Resource相關的處理方式。
4.創建對應Resource的WebService，在WebService中添加響應Route，并將WebService加入到Container中。
5.啟動監聽服務。

apiServer的Container相關的結構是APIContainer。
路徑：pkg/genericapiserver/mux/container.go

type APIContainer struct {
    *restful.Container
    NonSwaggerRoutes PathRecorderMux
    SecretRoutes     Mux
}

而該結構是在GenericAPIServer中被使用，分析過apiServer的啟動過程的話，應該對該結構比較熟悉。

type GenericAPIServer struct {
    discoveryAddresses DiscoveryAddresses

    LoopbackClientConfig *restclient.Config

    minRequestTimeout time.Duration

    ...

    requestContextMapper api.RequestContextMapper

    // 這里使用到了restful.Container
    HandlerContainer *genericmux.APIContainer

    SecureServingInfo   *SecureServingInfo
    InsecureServingInfo *ServingInfo

    effectiveSecurePort, effectiveInsecurePort int

    ExternalAddress string

    storage map[string]rest.Storage

    Serializer runtime.NegotiatedSerializer

    Handler         http.Handler
    InsecureHandler http.Handler

    apiGroupsForDiscoveryLock sync.RWMutex
    apiGroupsForDiscovery     map[string]unversioned.APIGroup

    ...
}

而該結構的初始化是在master的初始化過程中進行的。
調用過程： main --> App.Run --> master.Complete.New --> c.Config.GenericConfig.SkipComplete().New()
路徑： pkg/genericapiserver/config.go

func (c completedConfig) New() (*GenericAPIServer, error) {
    if c.Serializer == nil {
        return nil, fmt.Errorf("Genericapiserver.New() called with config.Serializer == nil")
    }

    s := &GenericAPIServer{
        discoveryAddresses:     c.DiscoveryAddresses,
        LoopbackClientConfig:   c.LoopbackClientConfig,
        legacyAPIGroupPrefixes: c.LegacyAPIGroupPrefixes,
        admissionControl:       c.AdmissionControl,
        requestContextMapper:   c.RequestContextMapper,
        Serializer:             c.Serializer,

        minRequestTimeout:    time.Duration(c.MinRequestTimeout) * time.Second,
        enableSwaggerSupport: c.EnableSwaggerSupport,

        SecureServingInfo:   c.SecureServingInfo,
        InsecureServingInfo: c.InsecureServingInfo,
        ExternalAddress:     c.ExternalAddress,

        apiGroupsForDiscovery: map[string]unversioned.APIGroup{},

        enableOpenAPISupport: c.EnableOpenAPISupport,
        openAPIConfig:        c.OpenAPIConfig,

        postStartHooks: map[string]postStartHookEntry{},
    }
    // 這里進行了Contianer的初始化
    s.HandlerContainer = mux.NewAPIContainer(http.NewServeMux(), c.Serializer)
    // 添加了DynamicApisDiscovery的
    s.installAPI(c.Config)

    s.Handler, s.InsecureHandler = c.BuildHandlerChainsFunc(s.HandlerContainer.ServeMux, c.Config)

    return s, nil
}

繼續調用mux.NewAPIContainer()接口創建，該接口的兩個參數：新建了一個http的ServeMux; 另一個是實現了編解碼序列化反序列化的對象

func NewAPIContainer(mux *http.ServeMux, s runtime.NegotiatedSerializer) *APIContainer {
    c := APIContainer{
        // New一個Container
        Container: restful.NewContainer(),
        NonSwaggerRoutes: PathRecorderMux{
            mux: mux,
        },
        SecretRoutes: mux,
    }
    // 配置http.ServeMux
    c.Container.ServeMux = mux
    // 配置該Container的路由方式：CurlyRouter 即快速路由
    c.Container.Router(restful.CurlyRouter{}) // e.g. for proxy/{kind}/{name}/{*}
    // 配置panic產生之后的恢復處理函數
    apiserver.InstallRecoverHandler(s, c.Container)
    apiserver.InstallServiceErrorHandler(s, c.Container)

    return &c
}

看下apiserver.InstallRecoverHandler()實現：

func InstallRecoverHandler(s runtime.NegotiatedSerializer, container *restful.Container) {
    container.RecoverHandler(func(panicReason interface{}, httpWriter http.ResponseWriter) {
        logStackOnRecover(s, panicReason, httpWriter)
    })
}

// RecoverHandler changes the default function (logStackOnRecover) to be called
// when a panic is detected. DoNotRecover must be have its default value (=false).
func (c *Container) RecoverHandler(handler RecoverHandleFunction) {
    c.recoverHandleFunc = handler
}

根據英文注釋可以看明白，該RecoverHandler就是在產生panic后會調用的恢復處理函數，默認的調用函數是logStackOnRecover,調用Container.RecoverHandler()后會修改該默認函數，并且Container.DoNotRecover的bool值必須是false才能生效。
apiserver.InstallServiceErrorHandler()接口就不看了，其實就是修改Service Error產生后的錯誤處理函數，默認是調用writeServiceError()。

到這里Container的初始化基本OK了。

Container已創建并且也進行了初始化。該輪到WebService了，這節會介紹k8s的WebService的創建及添加。
接續上文的Container初始化入口，繼續往下看s.installAPI(c.Config):

func (s *GenericAPIServer) installAPI(c *Config) {
    // 這里原本還有很多routes.Install()函數
    // 這些install()貌似和mux有關。
    // 而mux就是一個http的多分器，用于派發某個Request路徑到對應的http.Handler進行處理
    。。。
    // 往HandlerContainer中的Container里添加WebService
    // 該WebService的創建在s.DynamicApisDiscovery()中進行
    // 實際上創建的WebService是用于list 該group下的所有versions
    s.HandlerContainer.Add(s.DynamicApisDiscovery())
}

先看下WebService的創建接口s.DynamicApisDiscovery()：
路徑：pkg/genericapiserver/genericapiserver.go

// DynamicApisDiscovery returns a webservice serving api group discovery.
// Note: during the server runtime apiGroupsForDiscovery might change.
func (s *GenericAPIServer) DynamicApisDiscovery() *restful.WebService {
    return apiserver.NewApisWebService(s.Serializer, APIGroupPrefix, func(req *restful.Request) []unversioned.APIGroup {
        // 需要加鎖
        // 接口注釋也有說明。因為k8s可以動態加載第三方apiGroups
        s.apiGroupsForDiscoveryLock.RLock()
        defer s.apiGroupsForDiscoveryLock.RUnlock()

        // 將apiGroupsForDiscovery中所有的APIGroup按照其名字進行升序排序
        sortedGroups := []unversioned.APIGroup{}
        groupNames := make([]string, 0, len(s.apiGroupsForDiscovery))
        for groupName := range s.apiGroupsForDiscovery {
            groupNames = append(groupNames, groupName)
        }
        sort.Strings(groupNames)
        for _, groupName := range groupNames {
            sortedGroups = append(sortedGroups, s.apiGroupsForDiscovery[groupName])
        }
        // 創建切片，并填充各個APIGroup的ServerAddressByClientCIDRs信息
        clientIP := utilnet.GetClientIP(req.Request)
        serverCIDR := s.discoveryAddresses.ServerAddressByClientCIDRs(clientIP)
        groups := make([]unversioned.APIGroup, len(sortedGroups))
        for i := range sortedGroups {
            groups[i] = sortedGroups[i]
            groups[i].ServerAddressByClientCIDRs = serverCIDR
        }
        return groups
    })
}

繼續深入看apiserver.NewApisWebService()，該接口傳入了編解碼對象，APIGroup的Prefix，還有一個function。

func NewApisWebService(s runtime.NegotiatedSerializer, apiPrefix string, f func(req *restful.Request) []unversioned.APIGroup) *restful.WebService {
    // 用于向后兼容v1.1版本，返回一個空的APIGroup
    ss := StripVersionNegotiatedSerializer{s}
    // 獲取支持的媒體類型,比如：application/json，application/yaml
    mediaTypes, _ := mediaTypesForSerializer(s)
    // 構建go-restful的Route處理方法
    rootAPIHandler := RootAPIHandler(ss, f)
    // 創建WebService
    ws := new(restful.WebService)
    // 添加Path
    ws.Path(apiPrefix)
    // API 說明
    ws.Doc("get available API versions")
    // 配置GET("/") 轉到rootAPIHandler()接口
    ws.Route(ws.GET("/").To(rootAPIHandler).
        Doc("get available API versions").
        Operation("getAPIVersions").
        Produces(mediaTypes...).
        Consumes(mediaTypes...).
        Writes(unversioned.APIGroupList{}))
    return ws
}

到這里list某個Group下所有的versions的API已經注冊完成了。
這些都不是關鍵的RESTful API的注冊，關鍵的注冊都會在pkg/apiserver/apiserver.go中的InstallREST()接口中進行。
琢磨過apiServer啟動流程的同學，應該會知道/api和/apis的注冊接口最后都會調用到該接口。
/api的注冊接口是pkg/genericapiserver/genericapiserver.go中的InstallLegacyAPIGroup()接口
/apis的注冊接口是InstallAPIGroup()。
這兩個接口都會調用s.installAPIResources()，最后再調用apiGroupVersion.InstallREST()進行API注冊。
流程基本就是這樣，接著我們直接進入InstallREST()接口看實現：

func (g *APIGroupVersion) InstallREST(container *restful.Container) error {
    // 拼裝path: "Prefix/Group/Version"    
    // 然后填充并返回一個APIInstaller對象
    installer := g.newInstaller()
    // 創建一個WebService
    ws := installer.NewWebService()
    // 這個是關鍵，會對各種URL進行注冊
    apiResources, registrationErrors := installer.Install(ws)
    lister := g.ResourceLister
    if lister == nil {
        lister = staticLister{apiResources}
    }
    // 增加一個list的API
    AddSupportedResourcesWebService(g.Serializer, ws, g.GroupVersion, lister)
    // 將該WebService加入到Container
    container.Add(ws)
    return utilerrors.NewAggregate(registrationErrors)
}

前兩個調用函數比較簡單，這里不進行介紹了。直接進入關鍵函數installer.Install(ws)：

func (a *APIInstaller) Install(ws *restful.WebService) (apiResources []unversioned.APIResource, errors []error) {
    errors = make([]error, 0)

    proxyHandler := (&ProxyHandler{
        prefix:     a.prefix + "/proxy/",
        storage:    a.group.Storage,
        serializer: a.group.Serializer,
        mapper:     a.group.Context,
    })

    // 將所有的path合成一個切片，并按照升序重新排序
    paths := make([]string, len(a.group.Storage))
    var i int = 0
    for path := range a.group.Storage {
        paths[i] = path
        i++
    }
    sort.Strings(paths)
    for _, path := range paths {
        // 注冊各個URL,關鍵接口
        // 傳入的參數：path，rest.Storage，WebService，Handler
        apiResource, err := a.registerResourceHandlers(path, a.group.Storage[path], ws, proxyHandler)
        if err != nil {
            errors = append(errors, fmt.Errorf("error in registering resource: %s, %v", path, err))
        }
        // 將所有注冊成功的Resource合成一個切片
        // 將該切片作為返回值，便于之后的接口注冊list Resources的API
        if apiResource != nil {
            apiResources = append(apiResources, *apiResource)
        }
    }
    return apiResources, errors
}

該接口先是遍歷所有的path，并升序重新排列，然后循環調用接口注冊各個URL的API,并將這些注冊成功的APIResource加入到同一個切片中。
我們繼續看a.registerResourceHandlers()接口：

func (a *APIInstaller) registerResourceHandlers(path string, storage rest.Storage, ws *restful.WebService, proxyHandler http.Handler) (*unversioned.APIResource, error) {
    ...

    // 構建creater、lister、deleter、updater、watcher等，其實就是storage
    creater, isCreater := storage.(rest.Creater)
    namedCreater, isNamedCreater := storage.(rest.NamedCreater)
    lister, isLister := storage.(rest.Lister)
    getter, isGetter := storage.(rest.Getter)
    getterWithOptions, isGetterWithOptions := storage.(rest.GetterWithOptions)
    deleter, isDeleter := storage.(rest.Deleter)
    gracefulDeleter, isGracefulDeleter := storage.(rest.GracefulDeleter)
    collectionDeleter, isCollectionDeleter := storage.(rest.CollectionDeleter)
    updater, isUpdater := storage.(rest.Updater)
    patcher, isPatcher := storage.(rest.Patcher)
    watcher, isWatcher := storage.(rest.Watcher)
    _, isRedirector := storage.(rest.Redirector)
    connecter, isConnecter := storage.(rest.Connecter)
    storageMeta, isMetadata := storage.(rest.StorageMetadata)
    ...
    var apiResource unversioned.APIResource
    // k8s資源分為兩類：無namespace的RESTScopeNameRoot; 有namespace的RESTScopeNameNamespace
    // 在對應的path上添加各類actions，并指定對應的handler。
    switch scope.Name() {
    case meta.RESTScopeNameRoot:
        // Handle non-namespace scoped resources like nodes.
        resourcePath := resource
        resourceParams := params
        itemPath := resourcePath + "/{name}"
        nameParams := append(params, nameParam)
        proxyParams := append(nameParams, pathParam)
        suffix := ""
        if hasSubresource {
            suffix = "/" + subresource
            itemPath = itemPath + suffix
            resourcePath = itemPath
            resourceParams = nameParams
        }
        apiResource.Name = path
        apiResource.Namespaced = false
        apiResource.Kind = resourceKind
        namer := rootScopeNaming{scope, a.group.Linker, gpath.Join(a.prefix, resourcePath, "/"), suffix}

        // Handler for standard REST verbs (GET, PUT, POST and DELETE).
        // Add actions at the resource path: /api/apiVersion/resource
        actions = appendIf(actions, action{"LIST", resourcePath, resourceParams, namer, false}, isLister)
        actions = appendIf(actions, action{"POST", resourcePath, resourceParams, namer, false}, isCreater)
        actions = appendIf(actions, action{"DELETECOLLECTION", resourcePath, resourceParams, namer, false}, isCollectionDeleter)
        // DEPRECATED
        actions = appendIf(actions, action{"WATCHLIST", "watch/" + resourcePath, resourceParams, namer, false}, allowWatchList)

        // Add actions at the item path: /api/apiVersion/resource/{name}
        actions = appendIf(actions, action{"GET", itemPath, nameParams, namer, false}, isGetter)
        if getSubpath {
            actions = appendIf(actions, action{"GET", itemPath + "/{path:*}", proxyParams, namer, false}, isGetter)
        }
        actions = appendIf(actions, action{"PUT", itemPath, nameParams, namer, false}, isUpdater)
        actions = appendIf(actions, action{"PATCH", itemPath, nameParams, namer, false}, isPatcher)
        actions = appendIf(actions, action{"DELETE", itemPath, nameParams, namer, false}, isDeleter)
        actions = appendIf(actions, action{"WATCH", "watch/" + itemPath, nameParams, namer, false}, isWatcher)
        // We add "proxy" subresource to remove the need for the generic top level prefix proxy.
        // The generic top level prefix proxy is deprecated in v1.2, and will be removed in 1.3, or 1.4 at the latest.
        // TODO: DEPRECATED in v1.2.
        actions = appendIf(actions, action{"PROXY", "proxy/" + itemPath + "/{path:*}", proxyParams, namer, false}, isRedirector)
        // TODO: DEPRECATED in v1.2.
        actions = appendIf(actions, action{"PROXY", "proxy/" + itemPath, nameParams, namer, false}, isRedirector)
        actions = appendIf(actions, action{"CONNECT", itemPath, nameParams, namer, false}, isConnecter)
        actions = appendIf(actions, action{"CONNECT", itemPath + "/{path:*}", proxyParams, namer, false}, isConnecter && connectSubpath)
        break
    case meta.RESTScopeNameNamespace:
        ...
        break
    default:
        return nil, fmt.Errorf("unsupported restscope: %s", scope.Name())
    }

    ...
    // 根據之前生成的actions,進行遍歷
    // 然后在WebService中添加指定的route
    for _, action := range actions {
        versionedObject := storageMeta.ProducesObject(action.Verb)
        if versionedObject == nil {
            versionedObject = defaultVersionedObject
        }
        reqScope.Namer = action.Namer
        namespaced := ""
        if apiResource.Namespaced {
            namespaced = "Namespaced"
        }
        operationSuffix := ""
        if strings.HasSuffix(action.Path, "/{path:*}") {
            operationSuffix = operationSuffix + "WithPath"
        }
        if action.AllNamespaces {
            operationSuffix = operationSuffix + "ForAllNamespaces"
            namespaced = ""
        }
        // 判斷action的動作類型
        // 生成響應的handler，創建route添加到WebService中
        switch action.Verb {
        case "GET": // Get a resource.
            var handler restful.RouteFunction
            // 判斷是否有參數
            if isGetterWithOptions {
                handler = GetResourceWithOptions(getterWithOptions, reqScope)
            } else {
                handler = GetResource(getter, exporter, reqScope)
            }
            // 生成處理函數
            handler = metrics.InstrumentRouteFunc(action.Verb, resource, handler)
            doc := "read the specified " + kind
            if hasSubresource {
                doc = "read " + subresource + " of the specified " + kind
            }
            route := ws.GET(action.Path).To(handler).
                Doc(doc).
                Param(ws.QueryParameter("pretty", "If "true", then the output is pretty printed.")).
                Operation("read"+namespaced+kind+strings.Title(subresource)+operationSuffix).
                Produces(append(storageMeta.ProducesMIMETypes(action.Verb), mediaTypes...)...).
                Returns(http.StatusOK, "OK", versionedObject).
                Writes(versionedObject)
            if isGetterWithOptions {
                if err := addObjectParams(ws, route, versionedGetOptions); err != nil {
                    return nil, err
                }
            }
            if isExporter {
                if err := addObjectParams(ws, route, versionedExportOptions); err != nil {
                    return nil, err
                }
            }
            addParams(route, action.Params)
            ws.Route(route)
        case "LIST": // List all resources of a kind.
            ...
        case "PUT": // Update a resource.
            ...
        case "PATCH": // Partially update a resource
            ...
        case "POST": // Create a resource.
            ...
        case "DELETE": // Delete a resource.
            ...
        case "DELETECOLLECTION":
            ...
        case "WATCH": // Watch a resource.
            ...
        case "WATCHLIST": // Watch all resources of a kind.
            ...
        case "PROXY": // Proxy requests to a resource.
            ...
        case "CONNECT":
            ...
            }
        default:
            return nil, fmt.Errorf("unrecognized action verb: %s", action.Verb)
        }
        // Note: update GetAttribs() when adding a custom handler.
    }
    return &apiResource, nil
}

首先構建creater、lister、getter、deleter、updater、patcher、watcher，其實他們都是storage，只是對應著對etcd的不同操作。
然后針對所有的action，構建響應的handler。創建對應的route,最后把route添加到service里面。這樣就完成了api的注冊。

關鍵的REST API注冊基本就這樣結束了，除此之外還會有很多別的API的注冊：
比如APIGroupVersion.InstallREST()接口中的AddSupportedResourcesWebService(g.Serializer, ws, g.GroupVersion, lister)；
GenericAPIServer.InstallLegacyAPIGroup()接口中的apiserver.AddApiWebService()的調用；
等等。。
其實上面也注冊了各種REST API，比如像PodList,ServiceList,ReplicationControllerList等。這些就不深入了，都是大同小異。

1.go-restful example: http://ernestmicklei.com/2012...
2.go-restful api desgin: http://ernestmicklei.com/2012...
3.go-restful github code： https://github.com/emicklei/g...
4.go-restful GoDoc: https://godoc.org/github.com/...