kubelet源码分析（version： git tag 1.7.6）-白红宇

一、概述

　　kubelet源码入口：cmd/kubelet/kubelet.go main()

　　cmd/kubelet/app 包中的Run函数：

　查看先参数，kubelet.KubeletDeps

1 type KubeletDeps struct { 2     Builder KubeletBuilder 3     ContainerRuntimeOptions []kubecontainer.Option  4     Options                 []Option 5     Auth                server.AuthInterface                --------      interface， 重点关注【下面还有，以这个为例】 6     CAdvisorInterface       cadvisor.Interface 7     Cloud                   cloudprovider.Interface 8     ContainerManager        cm.ContainerManager 9     DockerClient            libdocker.Interface  　　　　　　　10     EventClient             v1core.EventsGetter11     KubeClient              clientset.Interface12     ExternalKubeClient      clientgoclientset.Interface13     Mounter                 mount.Interface14     NetworkPlugins          []network.NetworkPlugin15     OOMAdjuster             *oom.OOMAdjuster16     OSInterface             kubecontainer.OSInterface17     PodConfig               *config.PodConfig18     Recorder                record.EventRecorder19     Writer                  kubeio.Writer20     VolumePlugins           []volume.VolumePlugin21     TLSOptions              *server.TLSOptions22 }

　　以下为server.AuthInterface 接口定义：

1 // AuthInterface contains all methods required by the auth filters2 type AuthInterface interface {3     authenticator.Request     4     authorizer.RequestAttributesGetter5     authorizer.Authorizer     6 }

　　继续查看：

1 type Request interface { 2     AuthenticateRequest(req *http.Request) (user.Info, bool, error) 3 }   4  5 type RequestAttributesGetter interface { 6     GetRequestAttributes(user.Info, *http.Request) Attributes 7 }   8  9 type Authorizer interface {10     Authorize(a Attributes) (authorized bool, reason string, err error)11 }

　　KubeletDeps 结构体中其他的接口也类似；

二、流程分析

　　　　主要是参数的初始化判断，然后通过kubeDeps.ContainerManager进行管理；

　　该函数返回的是一个ContainerManager接口，如下：

1 // Manages the containers running on a machine. 2 type ContainerManager interface { 3     // Runs the container manager's housekeeping. 4     // - Ensures that the Docker daemon is in a container. 5     // - Creates the system container where all non-containerized processes run. 6     Start(*v1.Node, ActivePodsFunc) error 7  8     // Returns resources allocated to system cgroups in the machine. 9     // These cgroups include the system and Kubernetes services.10     SystemCgroupsLimit() v1.ResourceList11 12     // Returns a NodeConfig that is being used by the container manager.13     GetNodeConfig() NodeConfig14 15     // Returns internal Status.16     Status() Status17 18     // NewPodContainerManager is a factory method which returns a podContainerManager object19     // Returns a noop implementation if qos cgroup hierarchy is not enabled20     NewPodContainerManager() PodContainerManager21 22     // GetMountedSubsystems returns the mounted cgroup subsystems on the node23     GetMountedSubsystems() *CgroupSubsystems24 25     // GetQOSContainersInfo returns the names of top level QoS containers26     GetQOSContainersInfo() QOSContainersInfo27 28     // GetNodeAllocatable returns the amount of compute resources that have to be reserved from scheduling.29     GetNodeAllocatableReservation() v1.ResourceList30 31     // GetCapacity returns the amount of compute resources tracked by container manager available on the node.32     GetCapacity() v1.ResourceList33 34     // UpdateQOSCgroups performs housekeeping updates to ensure that the top35     // level QoS containers have their desired state in a thread-safe way36     UpdateQOSCgroups() error37 }

　　而结构体containerManagerImpl 实现了ContainerManager接口：

　　　　继续往下：

　　　进入函数，查看注释：

　　主要就是做一些基本验证：

　　　启动kublet服务：

1 func startKubelet(k kubelet.KubeletBootstrap, podCfg *config.PodConfig, kubeCfg *componentconfig.KubeletConfiguration, kubeDeps *kubelet.KubeletDeps) {       2     // start the kubelet       3     go wait.Until(func() { k.Run(podCfg.Updates()) }, 0, wait.NeverStop)　　# go routine， 这里主要是对接kube-api 4  5     // start the kubelet server     6     if kubeCfg.EnableServer {  7         go wait.Until(func() { 8             k.ListenAndServe(net.ParseIP(kubeCfg.Address), uint(kubeCfg.Port), kubeDeps.TLSOptions, kubeDeps.Auth, kubeCfg.EnableDebuggingHandlers, kubeCfg.EnableContentionProfiling) 9         }, 0, wait.NeverStop)   // *****10     }     if kubeCfg.ReadOnlyPort > 0 {  11         go wait.Until(func() {12             k.ListenAndServeReadOnly(net.ParseIP(kubeCfg.Address), uint(kubeCfg.ReadOnlyPort))13         }, 0, wait.NeverStop) 14     } 15 }

　　启动kubelet HTTP server:

1 // ListenAndServe runs the kubelet HTTP server.2 func (kl *Kubelet) ListenAndServe(address net.IP, port uint, tlsOptions *server.TLSOptions, auth server.AuthInterface, enableDebuggingHandlers, enableContentionProfiling bool) {3     server.ListenAndServeKubeletServer(kl, kl.resourceAnalyzer, address, port, tlsOptions, auth, enableDebuggingHandlers, enableContentionProfiling, kl.containerRuntime, kl.criHandler)4 }

　　continue:

1 // ListenAndServeKubeletServer initializes a server to respond to HTTP network requests on the Kubelet. 2 func ListenAndServeKubeletServer( 3     host HostInterface, 4     resourceAnalyzer stats.ResourceAnalyzer, 5     address net.IP, 6     port uint, 7     tlsOptions *TLSOptions, 8     auth AuthInterface, 9     enableDebuggingHandlers,10     enableContentionProfiling bool,11     runtime kubecontainer.Runtime,12     criHandler http.Handler) {    glog.Infof("Starting to listen on %s:%d", address, port)13     handler := NewServer(host, resourceAnalyzer, auth, enableDebuggingHandlers, enableContentionProfiling, runtime, criHandler)    s := &http.Server{14         Addr:           net.JoinHostPort(address.String(), strconv.FormatUint(uint64(port), 10)),15         Handler:        &handler,16         MaxHeaderBytes: 1 << 20, 17     }   18     if tlsOptions != nil {19         s.TLSConfig = tlsOptions.Config20         // Passing empty strings as the cert and key files means no21         // cert/keys are specified and GetCertificate in the TLSConfig22         // should be called instead.23         glog.Fatal(s.ListenAndServeTLS(tlsOptions.CertFile, tlsOptions.KeyFile))    } else {24         glog.Fatal(s.ListenAndServe())25     }   26 }