K8S APISERVER源码: 服务启动

文章目录

[隐藏]

• 启动流程
• Container初始化

基于版本 1.6.7

启动流程

• cmd/kube-apiserver/apiserver.go

func main() {     app.Run(s)  }  

• cmd/kube-apiserver/app/server.go

func Run(s *options.ServerRunOptions) error {      // 构建master配置信息      config, sharedInformers, err := BuildMasterConfig(s)      // 调用RunServer      return RunServer(config, sharedInformers, wait.NeverStop)  }    func RunServer(config *master.Config, sharedInformers informers.SharedInformerFactory, stopCh <-chan struct{}) error {      // 执行相关初始化      m, err := config.Complete().New()     // => TO: Container初始化      // 启动      return m.GenericAPIServer.PrepareRun().Run(stopCh)  // => next  }  

• vendor/k8s.io/apiserver/pkg/server/genericapiserver.go

启动主体函数都在这个文件中, 绑定地址/端口号, 并最终启动

func (s preparedGenericAPIServer) Run(stopCh <-chan struct{}) error {      s.NonBlockingRun(stopCh)  }    func (s preparedGenericAPIServer) NonBlockingRun(stopCh <-chan struct{}) error {      s.serveSecurely(internalStopCh)      // or      s.serveInsecurely(internalStopCh) // => next  }  

• vendor/k8s.io/apiserver/pkg/server/serve.go

func (s *GenericAPIServer) serveInsecurely(stopCh <-chan struct{}) error {      insecureServer := &http.Server{          Addr:           s.InsecureServingInfo.BindAddress,          Handler:        s.InsecureHandler,   // s.Hnalder for secure          MaxHeaderBytes: 1 << 20,      }     runServer(insecureServer, s.InsecureServingInfo.BindNetwork, stopCh) // => next  }      func runServer(server *http.Server, network string, stopCh <-chan struct{}) (int, error) {      go func() {          for {              var listener net.Listener              listener = tcpKeepAliveListener{ln.(*net.TCPListener)}              // *http.Server              err := server.Serve(listener)              }      }()  }  

Container初始化

• cmd/kube-apiserver/app/server.go

func RunServer(config *master.Config, sharedInformers informers.SharedInformerFactory, stopCh <-chan struct{}) error {      // 执行相关初始化      m, err := config.Complete().New()     // => TO: Container初始化      // 启动      return m.GenericAPIServer.PrepareRun().Run(stopCh)  // => next  }  

• kubernetes/pkg/master/master.go

func (c completedConfig) New() (*Master, error) {     // m.GenericAPIServer.HandlerContainer = APIContainer,   APIContainer.Container =  restful.NewContainer()      s, err := c.Config.GenericConfig.SkipComplete().New() // completion is done in Complete, no need for a second time     m := &Master{          GenericAPIServer: s,      }  }  

• vendor/k8s.io/apiserver/pkg/server/config.go

到这里, 完成了 s.Handler, s.InsecureHandler 的初始化

func (c completedConfig) New() (*GenericAPIServer, error) {    s := &GenericAPIServer{    }    // s.HandlerContainer = APIContainer      s.HandlerContainer = mux.NewAPIContainer(http.NewServeMux(), c.Serializer)  // => next 1      // 生成 Handler      s.Handler, s.InsecureHandler = c.BuildHandlerChainsFunc(s.HandlerContainer.ServeMux, c.Config)  // => next 2  }  

• 1: vendor/k8s.io/apiserver/pkg/server/mux/container.go

新建一个APIContainer, 包含

// NewAPIContainer constructs a new container for APIs  func NewAPIContainer(mux *http.ServeMux, s runtime.NegotiatedSerializer) *APIContainer {      c := APIContainer{          // 新建一个Container          Container: restful.NewContainer(),          NonSwaggerRoutes: PathRecorderMux{              mux: mux,          },          UnlistedRoutes: mux,      }      // 配置 http.ServerMux      c.Container.ServeMux = mux      // 配置路由方式, 使用CurlyRouter      c.Container.Router(restful.CurlyRouter{}) // e.g. for proxy/{kind}/{name}/{*}      return &c  }  

• 2: vendor/k8s.io/apiserver/pkg/server/config.go

type Config struct {      BuildHandlerChainsFunc func(apiHandler http.Handler, c *Config) (secure, insecure http.Handler)  }      func NewConfig() *Config {      return &Config{              BuildHandlerChainsFunc:      DefaultBuildHandlerChain,      }  }      func DefaultBuildHandlerChain(apiHandler http.Handler, c *Config) (secure, insecure http.Handler) {      return generic(protect(apiHandler)), generic(audit(apiHandler)) // add filters to handler  }  

注意, 这里传递的参数是: s.HandlerContainer.ServeMux, DefaultBuildHandlerChain的参数是apiHandler http.Handler, 前者包含后者interface定义的方法.

• net/http/server.go

type Handler interface {          ServeHTTP(ResponseWriter, *Request)  }    // ServeHTTP dispatches the request to the handler whose  // pattern most closely matches the request URL.  func (mux *ServeMux) ServeHTTP(w ResponseWriter, r *Request) {      if r.RequestURI == "*" {          if r.ProtoAtLeast(1, 1) {              w.Header().Set("Connection", "close")          }          w.WriteHeader(StatusBadRequest)          return      }      h, _ := mux.Handler(r)      h.ServeHTTP(w, r)  }  

初始化后, Hnalder 以及 InsecureHandler赋值Container, 然后在new Server前, 将handler放入

&http.Server{          Addr:           s.InsecureServingInfo.BindAddress,          Handler:        s.InsecureHandler,   // s.Hanlder for secure          MaxHeaderBytes: 1 << 20,  }  

原文出处：wklken -> http://www.wklken.me/posts/2017/09/23/source-apiserver-02.html