//go:build linux
// +build linux
/*
Copyright 2020 The Kubernetes Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
// Package nodeshutdown can watch for node level shutdown events and trigger graceful termination of pods running on the node prior to a system shutdown.
package nodeshutdown
import (
"fmt"
"path/filepath"
"sync"
"time"
v1 "k8s.io/api/core/v1"
utilfeature "k8s.io/apiserver/pkg/util/feature"
"k8s.io/client-go/tools/record"
"k8s.io/klog/v2"
"k8s.io/kubernetes/pkg/features"
kubeletevents "k8s.io/kubernetes/pkg/kubelet/events"
"k8s.io/kubernetes/pkg/kubelet/eviction"
"k8s.io/kubernetes/pkg/kubelet/lifecycle"
"k8s.io/kubernetes/pkg/kubelet/metrics"
"k8s.io/kubernetes/pkg/kubelet/nodeshutdown/systemd"
"k8s.io/kubernetes/pkg/kubelet/prober"
)
const (
nodeShutdownNotAdmittedReason = "NodeShutdown"
nodeShutdownNotAdmittedMessage = "Pod was rejected as the node is shutting down."
dbusReconnectPeriod = 1 * time.Second
localStorageStateFile = "graceful_node_shutdown_state"
)
var systemDbus = func() (dbusInhibiter, error) {
return systemd.NewDBusCon()
}
type dbusInhibiter interface {
CurrentInhibitDelay() (time.Duration, error)
InhibitShutdown() (systemd.InhibitLock, error)
ReleaseInhibitLock(lock systemd.InhibitLock) error
ReloadLogindConf() error
MonitorShutdown() (<-chan bool, error)
OverrideInhibitDelay(inhibitDelayMax time.Duration) error
}
// managerImpl has functions that can be used to interact with the Node Shutdown Manager.
type managerImpl struct {
logger klog.Logger
recorder record.EventRecorder
nodeRef *v1.ObjectReference
probeManager prober.Manager
getPods eviction.ActivePodsFunc
syncNodeStatus func()
dbusCon dbusInhibiter
inhibitLock systemd.InhibitLock
nodeShuttingDownMutex sync.Mutex
nodeShuttingDownNow bool
podManager *podManager
enableMetrics bool
storage storage
}
// NewManager returns a new node shutdown manager.
func NewManager(conf *Config) Manager {
if !utilfeature.DefaultFeatureGate.Enabled(features.GracefulNodeShutdown) {
m := managerStub{}
return m
}
podManager := newPodManager(conf)
// Disable if the configuration is empty
if len(podManager.shutdownGracePeriodByPodPriority) == 0 {
m := managerStub{}
return m
}
manager := &managerImpl{
logger: conf.Logger,
probeManager: conf.ProbeManager,
recorder: conf.Recorder,
nodeRef: conf.NodeRef,
getPods: conf.GetPodsFunc,
syncNodeStatus: conf.SyncNodeStatusFunc,
podManager: podManager,
enableMetrics: utilfeature.DefaultFeatureGate.Enabled(features.GracefulNodeShutdownBasedOnPodPriority),
storage: localStorage{
Path: filepath.Join(conf.StateDirectory, localStorageStateFile),
},
}
manager.logger.Info("Creating node shutdown manager",
"shutdownGracePeriodRequested", conf.ShutdownGracePeriodRequested,
"shutdownGracePeriodCriticalPods", conf.ShutdownGracePeriodCriticalPods,
"shutdownGracePeriodByPodPriority", podManager.shutdownGracePeriodByPodPriority,
)
return manager
}
// Admit rejects all pods if node is shutting
func (m *managerImpl) Admit(attrs *lifecycle.PodAdmitAttributes) lifecycle.PodAdmitResult {
nodeShuttingDown := m.ShutdownStatus() != nil
if nodeShuttingDown {
return lifecycle.PodAdmitResult{
Admit: false,
Reason: nodeShutdownNotAdmittedReason,
Message: nodeShutdownNotAdmittedMessage,
}
}
return lifecycle.PodAdmitResult{Admit: true}
}
// setMetrics sets the metrics for the node shutdown manager.
func (m *managerImpl) setMetrics() {
if m.enableMetrics && m.storage != nil {
sta := state{}
err := m.storage.Load(&sta)
if err != nil {
m.logger.Error(err, "Failed to load graceful shutdown state")
} else {
if !sta.StartTime.IsZero() {
metrics.GracefulShutdownStartTime.Set(timestamp(sta.StartTime))
}
if !sta.EndTime.IsZero() {
metrics.GracefulShutdownEndTime.Set(timestamp(sta.EndTime))
}
}
}
}
// Start starts the node shutdown manager and will start watching the node for shutdown events.
func (m *managerImpl) Start() error {
stop, err := m.start()
if err != nil {
return err
}
go func() {
for {
if stop != nil {
<-stop
}
time.Sleep(dbusReconnectPeriod)
m.logger.V(1).Info("Restarting watch for node shutdown events")
stop, err = m.start()
if err != nil {
m.logger.Error(err, "Unable to watch the node for shutdown events")
}
}
}()
m.setMetrics()
return nil
}
func (m *managerImpl) start() (chan struct{}, error) {
systemBus, err := systemDbus()
if err != nil {
return nil, err
}
m.dbusCon = systemBus
currentInhibitDelay, err := m.dbusCon.CurrentInhibitDelay()
if err != nil {
return nil, err
}
// If the logind's InhibitDelayMaxUSec as configured in (logind.conf) is less than periodRequested, attempt to update the value to periodRequested.
if periodRequested := m.podManager.periodRequested(); periodRequested > currentInhibitDelay {
err := m.dbusCon.OverrideInhibitDelay(periodRequested)
if err != nil {
return nil, fmt.Errorf("unable to override inhibit delay by shutdown manager: %v", err)
}
err = m.dbusCon.ReloadLogindConf()
if err != nil {
return nil, err
}
// Read the current inhibitDelay again, if the override was successful, currentInhibitDelay will be equal to shutdownGracePeriodRequested.
updatedInhibitDelay, err := m.dbusCon.CurrentInhibitDelay()
if err != nil {
return nil, err
}
if periodRequested > updatedInhibitDelay {
return nil, fmt.Errorf("node shutdown manager was unable to update logind InhibitDelayMaxSec to %v (ShutdownGracePeriod), current value of InhibitDelayMaxSec (%v) is less than requested ShutdownGracePeriod", periodRequested, updatedInhibitDelay)
}
}
err = m.acquireInhibitLock()
if err != nil {
return nil, err
}
events, err := m.dbusCon.MonitorShutdown()
if err != nil {
releaseErr := m.dbusCon.ReleaseInhibitLock(m.inhibitLock)
if releaseErr != nil {
return nil, fmt.Errorf("failed releasing inhibitLock: %v and failed monitoring shutdown: %v", releaseErr, err)
}
return nil, fmt.Errorf("failed to monitor shutdown: %v", err)
}
stop := make(chan struct{})
go func() {
// Monitor for shutdown events. This follows the logind Inhibit Delay pattern described on https://www.freedesktop.org/wiki/Software/systemd/inhibit/
// 1. When shutdown manager starts, an inhibit lock is taken.
// 2. When shutdown(true) event is received, process the shutdown and release the inhibit lock.
// 3. When shutdown(false) event is received, this indicates a previous shutdown was cancelled. In this case, acquire the inhibit lock again.
for {
select {
case isShuttingDown, ok := <-events:
if !ok {
m.logger.Error(err, "Ended to watching the node for shutdown events")
close(stop)
return
}
m.logger.V(1).Info("Shutdown manager detected new shutdown event, isNodeShuttingDownNow", "event", isShuttingDown)
var shutdownType string
if isShuttingDown {
shutdownType = "shutdown"
} else {
shutdownType = "cancelled"
}
m.logger.V(1).Info("Shutdown manager detected new shutdown event", "event", shutdownType)
if isShuttingDown {
m.recorder.Event(m.nodeRef, v1.EventTypeNormal, kubeletevents.NodeShutdown, "Shutdown manager detected shutdown event")
} else {
m.recorder.Event(m.nodeRef, v1.EventTypeNormal, kubeletevents.NodeShutdown, "Shutdown manager detected shutdown cancellation")
}
m.nodeShuttingDownMutex.Lock()
m.nodeShuttingDownNow = isShuttingDown
m.nodeShuttingDownMutex.Unlock()
if isShuttingDown {
// Update node status and ready condition
go m.syncNodeStatus()
m.processShutdownEvent()
} else {
_ = m.acquireInhibitLock()
}
}
}
}()
return stop, nil
}
func (m *managerImpl) acquireInhibitLock() error {
lock, err := m.dbusCon.InhibitShutdown()
if err != nil {
return err
}
if m.inhibitLock != 0 {
m.dbusCon.ReleaseInhibitLock(m.inhibitLock)
}
m.inhibitLock = lock
return nil
}
// ShutdownStatus will return an error if the node is currently shutting down.
func (m *managerImpl) ShutdownStatus() error {
m.nodeShuttingDownMutex.Lock()
defer m.nodeShuttingDownMutex.Unlock()
if m.nodeShuttingDownNow {
return fmt.Errorf("node is shutting down")
}
return nil
}
func (m *managerImpl) processShutdownEvent() error {
m.logger.V(1).Info("Shutdown manager processing shutdown event")
activePods := m.getPods()
defer func() {
m.dbusCon.ReleaseInhibitLock(m.inhibitLock)
m.logger.V(1).Info("Shutdown manager completed processing shutdown event, node will shutdown shortly")
}()
if m.enableMetrics && m.storage != nil {
startTime := time.Now()
err := m.storage.Store(state{
StartTime: startTime,
})
if err != nil {
m.logger.Error(err, "Failed to store graceful shutdown state")
}
metrics.GracefulShutdownStartTime.Set(timestamp(startTime))
metrics.GracefulShutdownEndTime.Set(0)
defer func() {
endTime := time.Now()
err := m.storage.Store(state{
StartTime: startTime,
EndTime: endTime,
})
if err != nil {
m.logger.Error(err, "Failed to store graceful shutdown state")
}
metrics.GracefulShutdownStartTime.Set(timestamp(endTime))
}()
}
return m.podManager.killPods(activePods)
}
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