// Run starts the kubelet reacting to config updates
func (kl *Kubelet) Run(updates <-chan kubetypes.PodUpdate) {
if kl.logServer == nil {
kl.logServer = http.StripPrefix("/logs/", http.FileServer(http.Dir("/var/log/")))
}
if kl.kubeClient == nil {
glog.Warning("No api server defined - no node status update will be sent.")
}
// Start the cloud provider sync manager
if kl.cloudResourceSyncManager != nil {
go kl.cloudResourceSyncManager.Run(wait.NeverStop)
}
if err := kl.initializeModules(); err != nil {
kl.recorder.Eventf(kl.nodeRef, v1.EventTypeWarning, events.KubeletSetupFailed, err.Error())
glog.Fatal(err)
}
// Start volume manager
go kl.volumeManager.Run(kl.sourcesReady, wait.NeverStop)
if kl.kubeClient != nil {
// Start syncing node status immediately, this may set up things the runtime needs to run.
go wait.Until(kl.syncNodeStatus, kl.nodeStatusUpdateFrequency, wait.NeverStop)
go kl.fastStatusUpdateOnce()
// start syncing lease
if utilfeature.DefaultFeatureGate.Enabled(features.NodeLease) {
go kl.nodeLeaseController.Run(wait.NeverStop)
}
}
go wait.Until(kl.updateRuntimeUp, 5*time.Second, wait.NeverStop)
// Start loop to sync iptables util rules
if kl.makeIPTablesUtilChains {
go wait.Until(kl.syncNetworkUtil, 1*time.Minute, wait.NeverStop)
}
// Start a goroutine responsible for killing pods (that are not properly
// handled by pod workers).
go wait.Until(kl.podKiller, 1*time.Second, wait.NeverStop)
// Start component sync loops.
kl.statusManager.Start()
kl.probeManager.Start()
// Start syncing RuntimeClasses if enabled.
if kl.runtimeClassManager != nil {
go kl.runtimeClassManager.Run(wait.NeverStop)
}
// Start the pod lifecycle event generator.
kl.pleg.Start()
kl.syncLoop(updates, kl)
}
// initializeModules will initialize internal modules that do not require the container runtime to be up.
// Note that the modules here must not depend on modules that are not initialized here.
func (kl *Kubelet) initializeModules() error {
// Prometheus metrics.
metrics.Register(kl.runtimeCache, collectors.NewVolumeStatsCollector(kl))
// Setup filesystem directories.
if err := kl.setupDataDirs(); err != nil {
return err
}
// If the container logs directory does not exist, create it.
if _, err := os.Stat(ContainerLogsDir); err != nil {
if err := kl.os.MkdirAll(ContainerLogsDir, 0755); err != nil {
glog.Errorf("Failed to create directory %q: %v", ContainerLogsDir, err)
}
}
// Start the image manager.
kl.imageManager.Start()
// Start the certificate manager if it was enabled.
if kl.serverCertificateManager != nil {
kl.serverCertificateManager.Start()
}
// Start out of memory watcher.
if err := kl.oomWatcher.Start(kl.nodeRef); err != nil {
return fmt.Errorf("Failed to start OOM watcher %v", err)
}
// Start resource analyzer
kl.resourceAnalyzer.Start()
return nil
}
3.1. setupDataDirs
initializeModules先创建相关目录。
具体目录如下：
ContainerLogsDir：目录为/var/log/containers。
rootDirectory：由参数传入，一般为/var/lib/kubelet。
PodsDir：目录为{rootDirectory}/pods。
PluginsDir：目录为{rootDirectory}/plugins。
initializeModules中setupDataDirs的相关代码如下：
// Setup filesystem directories.
if err := kl.setupDataDirs(); err != nil {
return err
}
// If the container logs directory does not exist, create it.
if _, err := os.Stat(ContainerLogsDir); err != nil {
if err := kl.os.MkdirAll(ContainerLogsDir, 0755); err != nil {
glog.Errorf("Failed to create directory %q: %v", ContainerLogsDir, err)
}
}
// Start the image manager.
kl.imageManager.Start()
// Start the certificate manager if it was enabled.
if kl.serverCertificateManager != nil {
kl.serverCertificateManager.Start()
}
// Start out of memory watcher.
if err := kl.oomWatcher.Start(kl.nodeRef); err != nil {
return fmt.Errorf("Failed to start OOM watcher %v", err)
}
// Start resource analyzer
kl.resourceAnalyzer.Start()
if kl.kubeClient != nil {
// Start syncing node status immediately, this may set up things the runtime needs to run.
go wait.Until(kl.syncNodeStatus, kl.nodeStatusUpdateFrequency, wait.NeverStop)
go kl.fastStatusUpdateOnce()
// start syncing lease
if utilfeature.DefaultFeatureGate.Enabled(features.NodeLease) {
go kl.nodeLeaseController.Run(wait.NeverStop)
}
}
go wait.Until(kl.updateRuntimeUp, 5*time.Second, wait.NeverStop)
4.4. syncNetworkUtil
通过循环的方式同步iptables的规则，不过当前代码并没有执行任何操作。
// Start loop to sync iptables util rules
if kl.makeIPTablesUtilChains {
go wait.Until(kl.syncNetworkUtil, 1*time.Minute, wait.NeverStop)
}
4.5. podKiller
但pod没有被podworker正确处理的时候，启动一个goroutine负责杀死pod。
// Start a goroutine responsible for killing pods (that are not properly
// handled by pod workers).
go wait.Until(kl.podKiller, 1*time.Second, wait.NeverStop)
podKiller代码如下：
此部分代码位于pkg/kubelet/kubelet_pods.go
// podKiller launches a goroutine to kill a pod received from the channel if
// another goroutine isn't already in action.
func (kl *Kubelet) podKiller() {
killing := sets.NewString()
// guard for the killing set
lock := sync.Mutex{}
for podPair := range kl.podKillingCh {
runningPod := podPair.RunningPod
apiPod := podPair.APIPod
lock.Lock()
exists := killing.Has(string(runningPod.ID))
if !exists {
killing.Insert(string(runningPod.ID))
}
lock.Unlock()
if !exists {
go func(apiPod *v1.Pod, runningPod *kubecontainer.Pod) {
glog.V(2).Infof("Killing unwanted pod %q", runningPod.Name)
err := kl.killPod(apiPod, runningPod, nil, nil)
if err != nil {
glog.Errorf("Failed killing the pod %q: %v", runningPod.Name, err)
}
lock.Lock()
killing.Delete(string(runningPod.ID))
lock.Unlock()
}(apiPod, runningPod)
}
}
}
func (m *manager) Start() {
// Don't start the status manager if we don't have a client. This will happen
// on the master, where the kubelet is responsible for bootstrapping the pods
// of the master components.
if m.kubeClient == nil {
glog.Infof("Kubernetes client is nil, not starting status manager.")
return
}
glog.Info("Starting to sync pod status with apiserver")
syncTicker := time.Tick(syncPeriod)
// syncPod and syncBatch share the same go routine to avoid sync races.
go wait.Forever(func() {
select {
case syncRequest := <-m.podStatusChannel:
glog.V(5).Infof("Status Manager: syncing pod: %q, with status: (%d, %v) from podStatusChannel",
syncRequest.podUID, syncRequest.status.version, syncRequest.status.status)
m.syncPod(syncRequest.podUID, syncRequest.status)
case <-syncTicker:
m.syncBatch()
}
}, 0)
}
4.7. probeManager
处理容器探针
kl.probeManager.Start()
4.8. runtimeClassManager
// Start syncing RuntimeClasses if enabled.
if kl.runtimeClassManager != nil {
go kl.runtimeClassManager.Run(wait.NeverStop)
}
4.9. PodLifecycleEventGenerator
// Start the pod lifecycle event generator.
kl.pleg.Start()
PodLifecycleEventGenerator是一个pod生命周期时间生成器接口，具体如下：
// PodLifecycleEventGenerator contains functions for generating pod life cycle events.
type PodLifecycleEventGenerator interface {
Start()
Watch() chan *PodLifecycleEvent
Healthy() (bool, error)
}
start方法具体实现如下：
// Start spawns a goroutine to relist periodically.
func (g *GenericPLEG) Start() {
go wait.Until(g.relist, g.relistPeriod, wait.NeverStop)
}
// syncLoop is the main loop for processing changes. It watches for changes from
// three channels (file, apiserver, and http) and creates a union of them. For
// any new change seen, will run a sync against desired state and running state. If
// no changes are seen to the configuration, will synchronize the last known desired
// state every sync-frequency seconds. Never returns.
func (kl *Kubelet) syncLoop(updates <-chan kubetypes.PodUpdate, handler SyncHandler) {
glog.Info("Starting kubelet main sync loop.")
// The resyncTicker wakes up kubelet to checks if there are any pod workers
// that need to be sync'd. A one-second period is sufficient because the
// sync interval is defaulted to 10s.
syncTicker := time.NewTicker(time.Second)
defer syncTicker.Stop()
housekeepingTicker := time.NewTicker(housekeepingPeriod)
defer housekeepingTicker.Stop()
plegCh := kl.pleg.Watch()
const (
base = 100 * time.Millisecond
max = 5 * time.Second
factor = 2
)
duration := base
for {
if rs := kl.runtimeState.runtimeErrors(); len(rs) != 0 {
glog.Infof("skipping pod synchronization - %v", rs)
// exponential backoff
time.Sleep(duration)
duration = time.Duration(math.Min(float64(max), factor*float64(duration)))
continue
}
// reset backoff if we have a success
duration = base
kl.syncLoopMonitor.Store(kl.clock.Now())
if !kl.syncLoopIteration(updates, handler, syncTicker.C, housekeepingTicker.C, plegCh) {
break
}
kl.syncLoopMonitor.Store(kl.clock.Now())
}
}
