// NewKubeletCommand creates a *cobra.Command object with default parameters
func NewKubeletCommand(stopCh <-chan struct{}) *cobra.Command {
...
cmd := &cobra.Command{
Use: componentKubelet,
Long: `...`,
// The Kubelet has special flag parsing requirements to enforce flag precedence rules,
// so we do all our parsing manually in Run, below.
// DisableFlagParsing=true provides the full set of flags passed to the kubelet in the
// `args` arg to Run, without Cobra's interference.
DisableFlagParsing: true,
Run: func(cmd *cobra.Command, args []string) {
...
// run the kubelet
glog.V(5).Infof("KubeletConfiguration: %#v", kubeletServer.KubeletConfiguration)
if err := Run(kubeletServer, kubeletDeps, stopCh); err != nil {
glog.Fatal(err)
}
},
}
...
return cmd
}
// initial flag parse, since we disable cobra's flag parsing
if err := cleanFlagSet.Parse(args); err != nil {
cmd.Usage()
glog.Fatal(err)
}
// check if there are non-flag arguments in the command line
cmds := cleanFlagSet.Args()
if len(cmds) > 0 {
cmd.Usage()
glog.Fatalf("unknown command: %s", cmds[0])
}
遇到help和version参数则打印相关内容并退出。
// short-circuit on help
help, err := cleanFlagSet.GetBool("help")
if err != nil {
glog.Fatal(`"help" flag is non-bool, programmer error, please correct`)
}
if help {
cmd.Help()
return
}
// short-circuit on verflag
verflag.PrintAndExitIfRequested()
utilflag.PrintFlags(cleanFlagSet)
// set feature gates from initial flags-based config
if err := utilfeature.DefaultFeatureGate.SetFromMap(kubeletConfig.FeatureGates); err != nil {
glog.Fatal(err)
}
// validate the initial KubeletFlags
if err := options.ValidateKubeletFlags(kubeletFlags); err != nil {
glog.Fatal(err)
}
if kubeletFlags.ContainerRuntime == "remote" && cleanFlagSet.Changed("pod-infra-container-image") {
glog.Warning("Warning: For remote container runtime, --pod-infra-container-image is ignored in kubelet, which should be set in that remote runtime instead")
}
// load kubelet config file, if provided
if configFile := kubeletFlags.KubeletConfigFile; len(configFile) > 0 {
kubeletConfig, err = loadConfigFile(configFile)
if err != nil {
glog.Fatal(err)
}
// We must enforce flag precedence by re-parsing the command line into the new object.
// This is necessary to preserve backwards-compatibility across binary upgrades.
// See issue #56171 for more details.
if err := kubeletConfigFlagPrecedence(kubeletConfig, args); err != nil {
glog.Fatal(err)
}
// update feature gates based on new config
if err := utilfeature.DefaultFeatureGate.SetFromMap(kubeletConfig.FeatureGates); err != nil {
glog.Fatal(err)
}
}
// We always validate the local configuration (command line + config file).
// This is the default "last-known-good" config for dynamic config, and must always remain valid.
if err := kubeletconfigvalidation.ValidateKubeletConfiguration(kubeletConfig); err != nil {
glog.Fatal(err)
}
2.1.4. dynamic kubelet config
如果开启使用动态kubelet的配置，则由动态配置文件替换kubelet配置文件。
// use dynamic kubelet config, if enabled
var kubeletConfigController *dynamickubeletconfig.Controller
if dynamicConfigDir := kubeletFlags.DynamicConfigDir.Value(); len(dynamicConfigDir) > 0 {
var dynamicKubeletConfig *kubeletconfiginternal.KubeletConfiguration
dynamicKubeletConfig, kubeletConfigController, err = BootstrapKubeletConfigController(dynamicConfigDir,
func(kc *kubeletconfiginternal.KubeletConfiguration) error {
// Here, we enforce flag precedence inside the controller, prior to the controller's validation sequence,
// so that we get a complete validation at the same point where we can decide to reject dynamic config.
// This fixes the flag-precedence component of issue #63305.
// See issue #56171 for general details on flag precedence.
return kubeletConfigFlagPrecedence(kc, args)
})
if err != nil {
glog.Fatal(err)
}
// If we should just use our existing, local config, the controller will return a nil config
if dynamicKubeletConfig != nil {
kubeletConfig = dynamicKubeletConfig
// Note: flag precedence was already enforced in the controller, prior to validation,
// by our above transform function. Now we simply update feature gates from the new config.
if err := utilfeature.DefaultFeatureGate.SetFromMap(kubeletConfig.FeatureGates); err != nil {
glog.Fatal(err)
}
}
}
// construct a KubeletServer from kubeletFlags and kubeletConfig
kubeletServer := &options.KubeletServer{
KubeletFlags: *kubeletFlags,
KubeletConfiguration: *kubeletConfig,
}
2.2.2. kubeletDeps
// use kubeletServer to construct the default KubeletDeps
kubeletDeps, err := UnsecuredDependencies(kubeletServer)
if err != nil {
glog.Fatal(err)
}
// add the kubelet config controller to kubeletDeps
kubeletDeps.KubeletConfigController = kubeletConfigController
2.2.3. docker shim
如果开启了docker shim参数，则执行RunDockershim。
// start the experimental docker shim, if enabled
if kubeletServer.KubeletFlags.ExperimentalDockershim {
if err := RunDockershim(&kubeletServer.KubeletFlags, kubeletConfig, stopCh); err != nil {
glog.Fatal(err)
}
return
}
2.3. AddFlags
// keep cleanFlagSet separate, so Cobra doesn't pollute it with the global flags
kubeletFlags.AddFlags(cleanFlagSet)
options.AddKubeletConfigFlags(cleanFlagSet, kubeletConfig)
options.AddGlobalFlags(cleanFlagSet)
cleanFlagSet.BoolP("help", "h", false, fmt.Sprintf("help for %s", cmd.Name()))
// ugly, but necessary, because Cobra's default UsageFunc and HelpFunc pollute the flagset with global flags
const usageFmt = "Usage:\n %s\n\nFlags:\n%s"
cmd.SetUsageFunc(func(cmd *cobra.Command) error {
fmt.Fprintf(cmd.OutOrStderr(), usageFmt, cmd.UseLine(), cleanFlagSet.FlagUsagesWrapped(2))
return nil
})
cmd.SetHelpFunc(func(cmd *cobra.Command, args []string) {
fmt.Fprintf(cmd.OutOrStdout(), "%s\n\n"+usageFmt, cmd.Long, cmd.UseLine(), cleanFlagSet.FlagUsagesWrapped(2))
})
// Run runs the specified KubeletServer with the given Dependencies. This should never exit.
// The kubeDeps argument may be nil - if so, it is initialized from the settings on KubeletServer.
// Otherwise, the caller is assumed to have set up the Dependencies object and a default one will
// not be generated.
func Run(s *options.KubeletServer, kubeDeps *kubelet.Dependencies, stopCh <-chan struct{}) error {
// To help debugging, immediately log version
glog.Infof("Version: %+v", version.Get())
if err := initForOS(s.KubeletFlags.WindowsService); err != nil {
return fmt.Errorf("failed OS init: %v", err)
}
if err := run(s, kubeDeps, stopCh); err != nil {
return fmt.Errorf("failed to run Kubelet: %v", err)
}
return nil
}
dynamicKubeClient, err = dynamic.NewForConfig(clientConfig)
if err != nil {
glog.Warningf("Failed to initialize dynamic KubeClient: %v", err)
}
3.1.4. eventClient
// make a separate client for events
eventClientConfig := *clientConfig
eventClientConfig.QPS = float32(s.EventRecordQPS)
eventClientConfig.Burst = int(s.EventBurst)
eventClient, err = v1core.NewForConfig(&eventClientConfig)
if err != nil {
glog.Warningf("Failed to create API Server client for Events: %v", err)
}
3.1.5. heartbeatClient
// make a separate client for heartbeat with throttling disabled and a timeout attached
heartbeatClientConfig := *clientConfig
heartbeatClientConfig.Timeout = s.KubeletConfiguration.NodeStatusUpdateFrequency.Duration
// if the NodeLease feature is enabled, the timeout is the minimum of the lease duration and status update frequency
if utilfeature.DefaultFeatureGate.Enabled(features.NodeLease) {
leaseTimeout := time.Duration(s.KubeletConfiguration.NodeLeaseDurationSeconds) * time.Second
if heartbeatClientConfig.Timeout > leaseTimeout {
heartbeatClientConfig.Timeout = leaseTimeout
}
}
heartbeatClientConfig.QPS = float32(-1)
heartbeatClient, err = clientset.NewForConfig(&heartbeatClientConfig)
if err != nil {
glog.Warningf("Failed to create API Server client for heartbeat: %v", err)
}
3.1.6. csiClient
// csiClient works with CRDs that support json only
clientConfig.ContentType = "application/json"
csiClient, err := csiclientset.NewForConfig(clientConfig)
if err != nil {
glog.Warningf("Failed to create CSI API client: %v", err)
}
// RunKubelet is responsible for setting up and running a kubelet. It is used in three different applications:
// 1 Integration tests
// 2 Kubelet binary
// 3 Standalone 'kubernetes' binary
// Eventually, #2 will be replaced with instances of #3
func RunKubelet(kubeServer *options.KubeletServer, kubeDeps *kubelet.Dependencies, runOnce bool) error {
...
k, err := CreateAndInitKubelet(&kubeServer.KubeletConfiguration,
...
kubeServer.NodeStatusMaxImages)
if err != nil {
return fmt.Errorf("failed to create kubelet: %v", err)
}
// NewMainKubelet should have set up a pod source config if one didn't exist
// when the builder was run. This is just a precaution.
if kubeDeps.PodConfig == nil {
return fmt.Errorf("failed to create kubelet, pod source config was nil")
}
podCfg := kubeDeps.PodConfig
rlimit.RlimitNumFiles(uint64(kubeServer.MaxOpenFiles))
// process pods and exit.
if runOnce {
if _, err := k.RunOnce(podCfg.Updates()); err != nil {
return fmt.Errorf("runonce failed: %v", err)
}
glog.Infof("Started kubelet as runonce")
} else {
startKubelet(k, podCfg, &kubeServer.KubeletConfiguration, kubeDeps, kubeServer.EnableServer)
glog.Infof("Started kubelet")
}
return nil
}
