kubernetes api-server 路由解析

 1. 简介

　　  apiserver使用go-restful来构建REST-style Web服务，所以我们先来了解一下这个包的相关内容，以便更好地理解apiserver的源码。

 

 

 3.　创建http server步骤

1. 创建Container。
2. 创建自定义的Resource Handle，实现Resource相关的处理方法。
3. 创建对应于Resource的WebService，在WebService中添加相应Route，并将WebService加入到Container中。
4. 启动监听服务。

　　

// APIServerHandlers holds the different http.Handlers used by the API server.
// This includes the full handler chain, the director (which chooses between gorestful and nonGoRestful,
// the gorestful handler (used for the API) which falls through to the nonGoRestful handler on unregistered paths,
// and the nonGoRestful handler (which can contain a fallthrough of its own)
// FullHandlerChain -> Director -> {GoRestfulContainer,NonGoRestfulMux} based on inspection of registered web services
type APIServerHandler struct {
	// FullHandlerChain is the one that is eventually served with.  It should include the full filter
	// chain and then call the Director.
	FullHandlerChain http.Handler
	// The registered APIs.  InstallAPIs uses this.  Other servers probably shouldn't access this directly.
	GoRestfulContainer *restful.Container
	// NonGoRestfulMux is the final HTTP handler in the chain.
	// It comes after all filters and the API handling
	// This is where other servers can attach handler to various parts of the chain.
	NonGoRestfulMux *mux.PathRecorderMux

	// Director is here so that we can properly handle fall through and proxy cases.
	// This looks a bit bonkers, but here's what's happening.  We need to have /apis handling registered in gorestful in order to have
	// swagger generated for compatibility.  Doing that with `/apis` as a webservice, means that it forcibly 404s (no defaulting allowed)
	// all requests which are not /apis or /apis/.  We need those calls to fall through behind goresful for proper delegation.  Trying to
	// register for a pattern which includes everything behind it doesn't work because gorestful negotiates for verbs and content encoding
	// and all those things go crazy when gorestful really just needs to pass through.  In addition, openapi enforces unique verb constraints
	// which we don't fit into and it still muddies up swagger.  Trying to switch the webservices into a route doesn't work because the
	//  containing webservice faces all the same problems listed above.
	// This leads to the crazy thing done here.  Our mux does what we need, so we'll place it in front of gorestful.  It will introspect to
	// decide if the route is likely to be handled by goresful and route there if needed.  Otherwise, it goes to PostGoRestful mux in
	// order to handle "normal" paths and delegation. Hopefully no API consumers will ever have to deal with this level of detail.  I think
	// we should consider completely removing gorestful.
	// Other servers should only use this opaquely to delegate to an API server.
	Director http.Handler
}

　　

　　3.1 创建 container

　　master.Config --> Complete() --->CompletedConfig ---> New()-->InstallAPIs --->InstallLegacyAPIGroup -> installAPIResource --> apiGroupVersion.InstallREST 

　　 container 容器为 ： s.Handler.GoRestfulContainer

　　3.2 创建handler

  s, err := c.GenericConfig.New("kube-apiserver", delegationTarget)
　　

// New creates a new server which logically combines the handling chain with the passed server.
// name is used to differentiate for logging. The handler chain in particular can be difficult as it starts delgating.
// delegationTarget may not be nil.
func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*GenericAPIServer, error) {

　　handlerChainBuilder := func(handler http.Handler) http.Handler {
  　　 return c.BuildHandlerChainFunc(handler, c.Config)
　　}
　　apiServerHandler := NewAPIServerHandler(name, c.Serializer, handlerChainBuilder, delegationTarget.UnprotectedHandler())

　

　　handlerChaninBuilderFn 用于包装gorestfulcontainer的处理器，提供处理链　

// HandlerChainBuilderFn is used to wrap the GoRestfulContainer handler using the provided handler chain.
// It is normally used to apply filtering like authentication and authorization
type HandlerChainBuilderFn func(apiHandler http.Handler) http.Handler

　　

func NewAPIServerHandler(name string, s runtime.NegotiatedSerializer, handlerChainBuilder HandlerChainBuilderFn, notFoundHandler http.Handler) *APIServerHandler {
	nonGoRestfulMux := mux.NewPathRecorderMux(name)
	if notFoundHandler != nil {
		nonGoRestfulMux.NotFoundHandler(notFoundHandler)
	}

	gorestfulContainer := restful.NewContainer()
        // ServeMux还负责清理URL请求路径，/重定向包含的任何请求。或者.。元素或重复的斜杠/作为等效的、更干净的URL。
	gorestfulContainer.ServeMux = http.NewServeMux()
　　　　　// 添加请求路径
	gorestfulContainer.Router(restful.CurlyRouter{}) // e.g. for proxy/{kind}/{name}/{*}
	gorestfulContainer.RecoverHandler(func(panicReason interface{}, httpWriter http.ResponseWriter) {
		logStackOnRecover(s, panicReason, httpWriter)
	})
	gorestfulContainer.ServiceErrorHandler(func(serviceErr restful.ServiceError, request *restful.Request, response *restful.Response) {
		serviceErrorHandler(s, serviceErr, request, response)
	})

	director := director{
		name:               name,
		goRestfulContainer: gorestfulContainer,
		nonGoRestfulMux:    nonGoRestfulMux,
	}

	return &APIServerHandler{
		FullHandlerChain:   handlerChainBuilder(director),
		GoRestfulContainer: gorestfulContainer,
		NonGoRestfulMux:    nonGoRestfulMux,
		Director:           director,
	}
}

　　https://blog.csdn.net/Daniel_greenspan/article/details/78624725

 

　　3.3 WebService加入到Container中

    apiResources, ws, registrationErrors := installer.Install()
　　

// InstallREST registers the REST handlers (storage, watch, proxy and redirect) into a restful Container.
// It is expected that the provided path root prefix will serve all operations. Root MUST NOT end
// in a slash.
func (g *APIGroupVersion) InstallREST(container *restful.Container) error {
	prefix := path.Join(g.Root, g.GroupVersion.Group, g.GroupVersion.Version)
	installer := &APIInstaller{
		group:                        g,
		prefix:                       prefix,
		minRequestTimeout:            g.MinRequestTimeout,
		enableAPIResponseCompression: g.EnableAPIResponseCompression,
	}

	apiResources, ws, registrationErrors := installer.Install()
	versionDiscoveryHandler := discovery.NewAPIVersionHandler(g.Serializer, g.GroupVersion, staticLister{apiResources})
	versionDiscoveryHandler.AddToWebService(ws)
	container.Add(ws)
	return utilerrors.NewAggregate(registrationErrors)
}

　　

// Install handlers for API resources.
func (a *APIInstaller) Install() ([]metav1.APIResource, *restful.WebService, []error) {
	var apiResources []metav1.APIResource
	var errors []error
	ws := a.newWebService()

	// Register the paths in a deterministic (sorted) order to get a deterministic swagger spec.
	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 {
		apiResource, err := a.registerResourceHandlers(path, a.group.Storage[path], ws)
		if err != nil {
			errors = append(errors, fmt.Errorf("error in registering resource: %s, %v", path, err))
		}
		if apiResource != nil {
			apiResources = append(apiResources, *apiResource)
		}
	}
	return apiResources, ws, errors
}

　　

 

 创建webservice

// newWebService creates a new restful webservice with the api installer's prefix and version.
func (a *APIInstaller) newWebService() *restful.WebService {
	ws := new(restful.WebService)
	ws.Path(a.prefix)
	// a.prefix contains "prefix/group/version"
	ws.Doc("API at " + a.prefix)
	// Backwards compatibility, we accepted objects with empty content-type at V1.
	// If we stop using go-restful, we can default empty content-type to application/json on an
	// endpoint by endpoint basis
	ws.Consumes("*/*")
	mediaTypes, streamMediaTypes := negotiation.MediaTypesForSerializer(a.group.Serializer)
	ws.Produces(append(mediaTypes, streamMediaTypes...)...)
	ws.ApiVersion(a.group.GroupVersion.String())

	return ws
}