kubelet源码分析(version: git tag 1.7.6)

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kubelet源码分析(version: git tag 1.7.6)

天色渐晚 2017-09-25 19:05:00 浏览1084
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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.EventsGetter
11     KubeClient              clientset.Interface
12     ExternalKubeClient      clientgoclientset.Interface
13     Mounter                 mount.Interface
14     NetworkPlugins          []network.NetworkPlugin
15     OOMAdjuster             *oom.OOMAdjuster
16     OSInterface             kubecontainer.OSInterface
17     PodConfig               *config.PodConfig
18     Recorder                record.EventRecorder
19     Writer                  kubeio.Writer
20     VolumePlugins           []volume.VolumePlugin
21     TLSOptions              *server.TLSOptions
22 }

   以下为server.AuthInterface 接口定义:

1 // AuthInterface contains all methods required by the auth filters
2 type AuthInterface interface {
3     authenticator.Request     
4     authorizer.RequestAttributesGetter
5     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.ResourceList
11 
12     // Returns a NodeConfig that is being used by the container manager.
13     GetNodeConfig() NodeConfig
14 
15     // Returns internal Status.
16     Status() Status
17 
18     // NewPodContainerManager is a factory method which returns a podContainerManager object
19     // Returns a noop implementation if qos cgroup hierarchy is not enabled
20     NewPodContainerManager() PodContainerManager
21 
22     // GetMountedSubsystems returns the mounted cgroup subsystems on the node
23     GetMountedSubsystems() *CgroupSubsystems
24 
25     // GetQOSContainersInfo returns the names of top level QoS containers
26     GetQOSContainersInfo() QOSContainersInfo
27 
28     // GetNodeAllocatable returns the amount of compute resources that have to be reserved from scheduling.
29     GetNodeAllocatableReservation() v1.ResourceList
30 
31     // GetCapacity returns the amount of compute resources tracked by container manager available on the node.
32     GetCapacity() v1.ResourceList
33 
34     // UpdateQOSCgroups performs housekeeping updates to ensure that the top
35     // level QoS containers have their desired state in a thread-safe way
36     UpdateQOSCgroups() error
37 }

  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.Config
20         // Passing empty strings as the cert and key files means no
21         // cert/keys are specified and GetCertificate in the TLSConfig
22         // should be called instead.
23         glog.Fatal(s.ListenAndServeTLS(tlsOptions.CertFile, tlsOptions.KeyFile))    } else {
24         glog.Fatal(s.ListenAndServe())
25     }   
26 }

 

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