kubelet.go

/*
Copyright 2015 The Kubernetes Authors All rights reserved.

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 kubelet

import (
	"bytes"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"os"
	"path"
	"path/filepath"
	goRuntime "runtime"
	"sort"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"github.com/golang/glog"
	cadvisorapi "github.com/google/cadvisor/info/v1"
	"k8s.io/kubernetes/pkg/api"
	apierrors "k8s.io/kubernetes/pkg/api/errors"
	utilpod "k8s.io/kubernetes/pkg/api/pod"
	"k8s.io/kubernetes/pkg/api/resource"
	"k8s.io/kubernetes/pkg/api/unversioned"
	"k8s.io/kubernetes/pkg/api/validation"
	"k8s.io/kubernetes/pkg/apis/componentconfig"
	"k8s.io/kubernetes/pkg/client/cache"
	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
	"k8s.io/kubernetes/pkg/client/record"
	"k8s.io/kubernetes/pkg/cloudprovider"
	"k8s.io/kubernetes/pkg/fieldpath"
	"k8s.io/kubernetes/pkg/fields"
	"k8s.io/kubernetes/pkg/kubelet/cadvisor"
	"k8s.io/kubernetes/pkg/kubelet/cm"
	"k8s.io/kubernetes/pkg/kubelet/config"
	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
	"k8s.io/kubernetes/pkg/kubelet/dockertools"
	"k8s.io/kubernetes/pkg/kubelet/envvars"
	"k8s.io/kubernetes/pkg/kubelet/eviction"
	"k8s.io/kubernetes/pkg/kubelet/lifecycle"
	"k8s.io/kubernetes/pkg/kubelet/metrics"
	"k8s.io/kubernetes/pkg/kubelet/network"
	"k8s.io/kubernetes/pkg/kubelet/pleg"
	kubepod "k8s.io/kubernetes/pkg/kubelet/pod"
	"k8s.io/kubernetes/pkg/kubelet/prober"
	proberesults "k8s.io/kubernetes/pkg/kubelet/prober/results"
	"k8s.io/kubernetes/pkg/kubelet/rkt"
	"k8s.io/kubernetes/pkg/kubelet/server"
	"k8s.io/kubernetes/pkg/kubelet/server/stats"
	"k8s.io/kubernetes/pkg/kubelet/status"
	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
	"k8s.io/kubernetes/pkg/kubelet/util/format"
	"k8s.io/kubernetes/pkg/kubelet/util/ioutils"
	"k8s.io/kubernetes/pkg/kubelet/util/queue"
	"k8s.io/kubernetes/pkg/runtime"
	"k8s.io/kubernetes/pkg/securitycontext"
	"k8s.io/kubernetes/pkg/types"
	"k8s.io/kubernetes/pkg/util"
	"k8s.io/kubernetes/pkg/util/bandwidth"
	utilerrors "k8s.io/kubernetes/pkg/util/errors"
	utilexec "k8s.io/kubernetes/pkg/util/exec"
	"k8s.io/kubernetes/pkg/util/flowcontrol"
	kubeio "k8s.io/kubernetes/pkg/util/io"
	"k8s.io/kubernetes/pkg/util/mount"
	utilnet "k8s.io/kubernetes/pkg/util/net"
	"k8s.io/kubernetes/pkg/util/oom"
	"k8s.io/kubernetes/pkg/util/procfs"
	utilruntime "k8s.io/kubernetes/pkg/util/runtime"
	"k8s.io/kubernetes/pkg/util/selinux"
	"k8s.io/kubernetes/pkg/util/sets"
	utilvalidation "k8s.io/kubernetes/pkg/util/validation"
	"k8s.io/kubernetes/pkg/util/validation/field"
	"k8s.io/kubernetes/pkg/util/wait"
	"k8s.io/kubernetes/pkg/version"
	"k8s.io/kubernetes/pkg/volume"
	"k8s.io/kubernetes/pkg/watch"
	"k8s.io/kubernetes/plugin/pkg/scheduler/algorithm/predicates"
	"k8s.io/kubernetes/plugin/pkg/scheduler/schedulercache"
	"k8s.io/kubernetes/third_party/golang/expansion"
)

const (
	// Max amount of time to wait for the container runtime to come up.
	maxWaitForContainerRuntime = 5 * time.Minute

	// nodeStatusUpdateRetry specifies how many times kubelet retries when posting node status failed.
	nodeStatusUpdateRetry = 5

	// Location of container logs.
	containerLogsDir = "/var/log/containers"

	// max backoff period, exported for the e2e test
	MaxContainerBackOff = 300 * time.Second

	// Capacity of the channel for storing pods to kill. A small number should
	// suffice because a goroutine is dedicated to check the channel and does
	// not block on anything else.
	podKillingChannelCapacity = 50

	// Period for performing global cleanup tasks.
	housekeepingPeriod = time.Second * 2

	// The path in containers' filesystems where the hosts file is mounted.
	etcHostsPath = "/etc/hosts"

	// Capacity of the channel for receiving pod lifecycle events. This number
	// is a bit arbitrary and may be adjusted in the future.
	plegChannelCapacity = 1000

	// Generic PLEG relies on relisting for discovering container events.
	// A longer period means that kubelet will take longer to detect container
	// changes and to update pod status. On the other hand, a shorter period
	// will cause more frequent relisting (e.g., container runtime operations),
	// leading to higher cpu usage.
	// Note that even though we set the period to 1s, the relisting itself can
	// take more than 1s to finish if the container runtime responds slowly
	// and/or when there are many container changes in one cycle.
	plegRelistPeriod = time.Second * 1

	// backOffPeriod is the period to back off when pod syncing results in an
	// error. It is also used as the base period for the exponential backoff
	// container restarts and image pulls.
	backOffPeriod = time.Second * 10

	// Period for performing container garbage collection.
	ContainerGCPeriod = time.Minute
	// Period for performing image garbage collection.
	ImageGCPeriod = 5 * time.Minute

	// Maximum period to wait for pod volume setup operations
	maxWaitForVolumeOps = 20 * time.Minute
)

// SyncHandler is an interface implemented by Kubelet, for testability
type SyncHandler interface {
	HandlePodAdditions(pods []*api.Pod)
	HandlePodUpdates(pods []*api.Pod)
	HandlePodDeletions(pods []*api.Pod)
	HandlePodReconcile(pods []*api.Pod)
	HandlePodSyncs(pods []*api.Pod)
	HandlePodCleanups() error
}

// Option is a functional option type for Kubelet
type Option func(*Kubelet)

// NewMainKubelet instantiates a new Kubelet object along with all the required internal modules.
// No initialization of Kubelet and its modules should happen here.
func NewMainKubelet(
	hostname string,
	nodeName string,
	dockerClient dockertools.DockerInterface,
	kubeClient clientset.Interface,
	rootDirectory string,
	podInfraContainerImage string,
	resyncInterval time.Duration,
	pullQPS float32,
	pullBurst int,
	eventQPS float32,
	eventBurst int,
	containerGCPolicy kubecontainer.ContainerGCPolicy,
	sourcesReadyFn config.SourcesReadyFn,
	registerNode bool,
	registerSchedulable bool,
	standaloneMode bool,
	clusterDomain string,
	clusterDNS net.IP,
	masterServiceNamespace string,
	volumePlugins []volume.VolumePlugin,
	networkPlugins []network.NetworkPlugin,
	networkPluginName string,
	streamingConnectionIdleTimeout time.Duration,
	recorder record.EventRecorder,
	cadvisorInterface cadvisor.Interface,
	imageGCPolicy ImageGCPolicy,
	diskSpacePolicy DiskSpacePolicy,
	cloud cloudprovider.Interface,
	nodeLabels map[string]string,
	nodeStatusUpdateFrequency time.Duration,
	osInterface kubecontainer.OSInterface,
	cgroupRoot string,
	containerRuntime string,
	rktPath string,
	rktAPIEndpoint string,
	rktStage1Image string,
	mounter mount.Interface,
	writer kubeio.Writer,
	configureCBR0 bool,
	nonMasqueradeCIDR string,
	podCIDR string,
	reconcileCIDR bool,
	maxPods int,
	nvidiaGPUs int,
	dockerExecHandler dockertools.ExecHandler,
	resolverConfig string,
	cpuCFSQuota bool,
	daemonEndpoints *api.NodeDaemonEndpoints,
	oomAdjuster *oom.OOMAdjuster,
	serializeImagePulls bool,
	containerManager cm.ContainerManager,
	outOfDiskTransitionFrequency time.Duration,
	flannelExperimentalOverlay bool,
	nodeIP net.IP,
	reservation kubetypes.Reservation,
	enableCustomMetrics bool,
	volumeStatsAggPeriod time.Duration,
	containerRuntimeOptions []kubecontainer.Option,
	hairpinMode string,
	babysitDaemons bool,
	evictionConfig eviction.Config,
	kubeOptions []Option,
) (*Kubelet, error) {
	if rootDirectory == "" {
		return nil, fmt.Errorf("invalid root directory %q", rootDirectory)
	}
	if resyncInterval <= 0 {
		return nil, fmt.Errorf("invalid sync frequency %d", resyncInterval)
	}

	serviceStore := cache.NewStore(cache.MetaNamespaceKeyFunc)
	if kubeClient != nil {
		// TODO: cache.NewListWatchFromClient is limited as it takes a client implementation rather
		// than an interface. There is no way to construct a list+watcher using resource name.
		listWatch := &cache.ListWatch{
			ListFunc: func(options api.ListOptions) (runtime.Object, error) {
				return kubeClient.Core().Services(api.NamespaceAll).List(options)
			},
			WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
				return kubeClient.Core().Services(api.NamespaceAll).Watch(options)
			},
		}
		cache.NewReflector(listWatch, &api.Service{}, serviceStore, 0).Run()
	}
	serviceLister := &cache.StoreToServiceLister{Store: serviceStore}

	nodeStore := cache.NewStore(cache.MetaNamespaceKeyFunc)
	if kubeClient != nil {
		// TODO: cache.NewListWatchFromClient is limited as it takes a client implementation rather
		// than an interface. There is no way to construct a list+watcher using resource name.
		fieldSelector := fields.Set{api.ObjectNameField: nodeName}.AsSelector()
		listWatch := &cache.ListWatch{
			ListFunc: func(options api.ListOptions) (runtime.Object, error) {
				options.FieldSelector = fieldSelector
				return kubeClient.Core().Nodes().List(options)
			},
			WatchFunc: func(options api.ListOptions) (watch.Interface, error) {
				options.FieldSelector = fieldSelector
				return kubeClient.Core().Nodes().Watch(options)
			},
		}
		cache.NewReflector(listWatch, &api.Node{}, nodeStore, 0).Run()
	}
	nodeLister := &cache.StoreToNodeLister{Store: nodeStore}
	nodeInfo := &predicates.CachedNodeInfo{StoreToNodeLister: nodeLister}

	// TODO: get the real node object of ourself,
	// and use the real node name and UID.
	// TODO: what is namespace for node?
	nodeRef := &api.ObjectReference{
		Kind:      "Node",
		Name:      nodeName,
		UID:       types.UID(nodeName),
		Namespace: "",
	}

	diskSpaceManager, err := newDiskSpaceManager(cadvisorInterface, diskSpacePolicy)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize disk manager: %v", err)
	}
	containerRefManager := kubecontainer.NewRefManager()

	volumeManager := newVolumeManager()

	oomWatcher := NewOOMWatcher(cadvisorInterface, recorder)

	// TODO: remove when internal cbr0 implementation gets removed in favor
	// of the kubenet network plugin
	if networkPluginName == "kubenet" {
		configureCBR0 = false
		flannelExperimentalOverlay = false
	}

	klet := &Kubelet{
		hostname:                       hostname,
		nodeName:                       nodeName,
		dockerClient:                   dockerClient,
		kubeClient:                     kubeClient,
		rootDirectory:                  rootDirectory,
		resyncInterval:                 resyncInterval,
		containerRefManager:            containerRefManager,
		httpClient:                     &http.Client{},
		sourcesReady:                   config.NewSourcesReady(sourcesReadyFn),
		registerNode:                   registerNode,
		registerSchedulable:            registerSchedulable,
		standaloneMode:                 standaloneMode,
		clusterDomain:                  clusterDomain,
		clusterDNS:                     clusterDNS,
		serviceLister:                  serviceLister,
		nodeLister:                     nodeLister,
		nodeInfo:                       nodeInfo,
		masterServiceNamespace:         masterServiceNamespace,
		streamingConnectionIdleTimeout: streamingConnectionIdleTimeout,
		recorder:                       recorder,
		cadvisor:                       cadvisorInterface,
		diskSpaceManager:               diskSpaceManager,
		volumeManager:                  volumeManager,
		cloud:                          cloud,
		nodeRef:                        nodeRef,
		nodeLabels:                     nodeLabels,
		nodeStatusUpdateFrequency:      nodeStatusUpdateFrequency,
		os:                         osInterface,
		oomWatcher:                 oomWatcher,
		cgroupRoot:                 cgroupRoot,
		mounter:                    mounter,
		writer:                     writer,
		configureCBR0:              configureCBR0,
		nonMasqueradeCIDR:          nonMasqueradeCIDR,
		reconcileCIDR:              reconcileCIDR,
		maxPods:                    maxPods,
		nvidiaGPUs:                 nvidiaGPUs,
		syncLoopMonitor:            atomic.Value{},
		resolverConfig:             resolverConfig,
		cpuCFSQuota:                cpuCFSQuota,
		daemonEndpoints:            daemonEndpoints,
		containerManager:           containerManager,
		flannelExperimentalOverlay: flannelExperimentalOverlay,
		flannelHelper:              NewFlannelHelper(),
		nodeIP:                     nodeIP,
		clock:                      util.RealClock{},
		outOfDiskTransitionFrequency: outOfDiskTransitionFrequency,
		reservation:                  reservation,
		enableCustomMetrics:          enableCustomMetrics,
		babysitDaemons:               babysitDaemons,
	}

	if klet.flannelExperimentalOverlay {
		glog.Infof("Flannel is in charge of podCIDR and overlay networking.")
	}
	if klet.nodeIP != nil {
		if err := klet.validateNodeIP(); err != nil {
			return nil, err
		}
		glog.Infof("Using node IP: %q", klet.nodeIP.String())
	}

	if mode, err := effectiveHairpinMode(componentconfig.HairpinMode(hairpinMode), containerRuntime, configureCBR0, networkPluginName); err != nil {
		// This is a non-recoverable error. Returning it up the callstack will just
		// lead to retries of the same failure, so just fail hard.
		glog.Fatalf("Invalid hairpin mode: %v", err)
	} else {
		klet.hairpinMode = mode
	}
	glog.Infof("Hairpin mode set to %q", klet.hairpinMode)

	if plug, err := network.InitNetworkPlugin(networkPlugins, networkPluginName, &networkHost{klet}, klet.hairpinMode); err != nil {
		return nil, err
	} else {
		klet.networkPlugin = plug
	}

	machineInfo, err := klet.GetCachedMachineInfo()
	if err != nil {
		return nil, err
	}

	procFs := procfs.NewProcFS()
	imageBackOff := flowcontrol.NewBackOff(backOffPeriod, MaxContainerBackOff)

	klet.livenessManager = proberesults.NewManager()

	klet.podCache = kubecontainer.NewCache()
	klet.podManager = kubepod.NewBasicPodManager(kubepod.NewBasicMirrorClient(klet.kubeClient))

	// Initialize the runtime.
	switch containerRuntime {
	case "docker":
		// Only supported one for now, continue.
		klet.containerRuntime = dockertools.NewDockerManager(
			dockerClient,
			kubecontainer.FilterEventRecorder(recorder),
			klet.livenessManager,
			containerRefManager,
			klet.podManager,
			machineInfo,
			podInfraContainerImage,
			pullQPS,
			pullBurst,
			containerLogsDir,
			osInterface,
			klet.networkPlugin,
			klet,
			klet.httpClient,
			dockerExecHandler,
			oomAdjuster,
			procFs,
			klet.cpuCFSQuota,
			imageBackOff,
			serializeImagePulls,
			enableCustomMetrics,
			klet.hairpinMode == componentconfig.HairpinVeth,
			containerRuntimeOptions...,
		)
	case "rkt":
		// TODO: Include hairpin mode settings in rkt?
		conf := &rkt.Config{
			Path:            rktPath,
			Stage1Image:     rktStage1Image,
			InsecureOptions: "image,ondisk",
		}
		rktRuntime, err := rkt.New(
			rktAPIEndpoint,
			conf,
			klet,
			recorder,
			containerRefManager,
			klet.podManager,
			klet.livenessManager,
			klet.volumeManager,
			klet.httpClient,
			utilexec.New(),
			kubecontainer.RealOS{},
			imageBackOff,
			serializeImagePulls,
		)
		if err != nil {
			return nil, err
		}
		klet.containerRuntime = rktRuntime
	default:
		return nil, fmt.Errorf("unsupported container runtime %q specified", containerRuntime)
	}

	// TODO: Factor out "StatsProvider" from Kubelet so we don't have a cyclic dependency
	klet.resourceAnalyzer = stats.NewResourceAnalyzer(klet, volumeStatsAggPeriod, klet.containerRuntime)

	klet.pleg = pleg.NewGenericPLEG(klet.containerRuntime, plegChannelCapacity, plegRelistPeriod, klet.podCache, util.RealClock{})
	klet.runtimeState = newRuntimeState(maxWaitForContainerRuntime)
	klet.updatePodCIDR(podCIDR)

	// setup containerGC
	containerGC, err := kubecontainer.NewContainerGC(klet.containerRuntime, containerGCPolicy)
	if err != nil {
		return nil, err
	}
	klet.containerGC = containerGC

	// setup imageManager
	imageManager, err := newImageManager(klet.containerRuntime, cadvisorInterface, recorder, nodeRef, imageGCPolicy)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize image manager: %v", err)
	}
	klet.imageManager = imageManager

	klet.runner = klet.containerRuntime
	klet.statusManager = status.NewManager(kubeClient, klet.podManager)

	klet.probeManager = prober.NewManager(
		klet.statusManager,
		klet.livenessManager,
		klet.runner,
		containerRefManager,
		recorder)

	if err := klet.volumePluginMgr.InitPlugins(volumePlugins, &volumeHost{klet}); err != nil {
		return nil, err
	}

	runtimeCache, err := kubecontainer.NewRuntimeCache(klet.containerRuntime)
	if err != nil {
		return nil, err
	}
	klet.runtimeCache = runtimeCache
	klet.reasonCache = NewReasonCache()
	klet.workQueue = queue.NewBasicWorkQueue(klet.clock)
	klet.podWorkers = newPodWorkers(klet.syncPod, recorder, klet.workQueue, klet.resyncInterval, backOffPeriod, klet.podCache)

	klet.backOff = flowcontrol.NewBackOff(backOffPeriod, MaxContainerBackOff)
	klet.podKillingCh = make(chan *kubecontainer.PodPair, podKillingChannelCapacity)
	klet.setNodeStatusFuncs = klet.defaultNodeStatusFuncs()

	// apply functional Option's
	for _, opt := range kubeOptions {
		opt(klet)
	}
	return klet, nil
}

// effectiveHairpinMode determines the effective hairpin mode given the
// configured mode, container runtime, and whether cbr0 should be configured.
func effectiveHairpinMode(hairpinMode componentconfig.HairpinMode, containerRuntime string, configureCBR0 bool, networkPlugin string) (componentconfig.HairpinMode, error) {
	// The hairpin mode setting doesn't matter if:
	// - We're not using a bridge network. This is hard to check because we might
	//   be using a plugin. It matters if --configure-cbr0=true, and we currently
	//   don't pipe it down to any plugins.
	// - It's set to hairpin-veth for a container runtime that doesn't know how
	//   to set the hairpin flag on the veth's of containers. Currently the
	//   docker runtime is the only one that understands this.
	// - It's set to "none".
	if hairpinMode == componentconfig.PromiscuousBridge || hairpinMode == componentconfig.HairpinVeth {
		// Only on docker.
		if containerRuntime != "docker" {
			glog.Warningf("Hairpin mode set to %q but container runtime is %q, ignoring", hairpinMode, containerRuntime)
			return componentconfig.HairpinNone, nil
		}
		if hairpinMode == componentconfig.PromiscuousBridge && !configureCBR0 && networkPlugin != "kubenet" {
			// This is not a valid combination.  Users might be using the
			// default values (from before the hairpin-mode flag existed) and we
			// should keep the old behavior.
			glog.Warningf("Hairpin mode set to %q but configureCBR0 is false, falling back to %q", hairpinMode, componentconfig.HairpinVeth)
			return componentconfig.HairpinVeth, nil
		}
	} else if hairpinMode == componentconfig.HairpinNone {
		if configureCBR0 {
			glog.Warningf("Hairpin mode set to %q and configureCBR0 is true, this might result in loss of hairpin packets", hairpinMode)
		}
	} else {
		return "", fmt.Errorf("unknown value: %q", hairpinMode)
	}
	return hairpinMode, nil
}

type serviceLister interface {
	List() (api.ServiceList, error)
}

type nodeLister interface {
	List() (machines api.NodeList, err error)
}

// Kubelet is the main kubelet implementation.
type Kubelet struct {
	hostname      string
	nodeName      string
	dockerClient  dockertools.DockerInterface
	runtimeCache  kubecontainer.RuntimeCache
	kubeClient    clientset.Interface
	rootDirectory string

	// podWorkers handle syncing Pods in response to events.
	podWorkers PodWorkers

	// resyncInterval is the interval between periodic full reconciliations of
	// pods on this node.
	resyncInterval time.Duration

	// sourcesReady records the sources seen by the kubelet, it is thread-safe.
	sourcesReady config.SourcesReady

	// podManager is a facade that abstracts away the various sources of pods
	// this Kubelet services.
	podManager kubepod.Manager

	// Needed to report events for containers belonging to deleted/modified pods.
	// Tracks references for reporting events
	containerRefManager *kubecontainer.RefManager

	// Optional, defaults to /logs/ from /var/log
	logServer http.Handler
	// Optional, defaults to simple Docker implementation
	runner kubecontainer.ContainerCommandRunner
	// Optional, client for http requests, defaults to empty client
	httpClient kubetypes.HttpGetter

	// cAdvisor used for container information.
	cadvisor cadvisor.Interface

	// Set to true to have the node register itself with the apiserver.
	registerNode bool
	// Set to true to have the node register itself as schedulable.
	registerSchedulable bool
	// for internal book keeping; access only from within registerWithApiserver
	registrationCompleted bool

	// Set to true if the kubelet is in standalone mode (i.e. setup without an apiserver)
	standaloneMode bool

	// If non-empty, use this for container DNS search.
	clusterDomain string

	// If non-nil, use this for container DNS server.
	clusterDNS net.IP

	// masterServiceNamespace is the namespace that the master service is exposed in.
	masterServiceNamespace string
	// serviceLister knows how to list services
	serviceLister serviceLister
	// nodeLister knows how to list nodes
	nodeLister nodeLister
	// nodeInfo knows how to get information about the node for this kubelet.
	nodeInfo predicates.NodeInfo

	// a list of node labels to register
	nodeLabels map[string]string

	// Last timestamp when runtime responded on ping.
	// Mutex is used to protect this value.
	runtimeState *runtimeState

	// Volume plugins.
	volumePluginMgr volume.VolumePluginMgr

	// Network plugin.
	networkPlugin network.NetworkPlugin

	// Handles container probing.
	probeManager prober.Manager
	// Manages container health check results.
	livenessManager proberesults.Manager

	// How long to keep idle streaming command execution/port forwarding
	// connections open before terminating them
	streamingConnectionIdleTimeout time.Duration

	// The EventRecorder to use
	recorder record.EventRecorder

	// Policy for handling garbage collection of dead containers.
	containerGC kubecontainer.ContainerGC

	// Manager for images.
	imageManager imageManager

	// Diskspace manager.
	diskSpaceManager diskSpaceManager

	// Cached MachineInfo returned by cadvisor.
	machineInfo *cadvisorapi.MachineInfo

	// Syncs pods statuses with apiserver; also used as a cache of statuses.
	statusManager status.Manager

	// Manager for the volume maps for the pods.
	volumeManager *volumeManager

	//Cloud provider interface
	cloud cloudprovider.Interface

	// Reference to this node.
	nodeRef *api.ObjectReference

	// Container runtime.
	containerRuntime kubecontainer.Runtime

	// reasonCache caches the failure reason of the last creation of all containers, which is
	// used for generating ContainerStatus.
	reasonCache *ReasonCache

	// nodeStatusUpdateFrequency specifies how often kubelet posts node status to master.
	// Note: be cautious when changing the constant, it must work with nodeMonitorGracePeriod
	// in nodecontroller. There are several constraints:
	// 1. nodeMonitorGracePeriod must be N times more than nodeStatusUpdateFrequency, where
	//    N means number of retries allowed for kubelet to post node status. It is pointless
	//    to make nodeMonitorGracePeriod be less than nodeStatusUpdateFrequency, since there
	//    will only be fresh values from Kubelet at an interval of nodeStatusUpdateFrequency.
	//    The constant must be less than podEvictionTimeout.
	// 2. nodeStatusUpdateFrequency needs to be large enough for kubelet to generate node
	//    status. Kubelet may fail to update node status reliably if the value is too small,
	//    as it takes time to gather all necessary node information.
	nodeStatusUpdateFrequency time.Duration

	// Generates pod events.
	pleg pleg.PodLifecycleEventGenerator

	// Store kubecontainer.PodStatus for all pods.
	podCache kubecontainer.Cache

	// os is a facade for various syscalls that need to be mocked during testing.
	os kubecontainer.OSInterface

	// Watcher of out of memory events.
	oomWatcher OOMWatcher

	// Monitor resource usage
	resourceAnalyzer stats.ResourceAnalyzer

	// If non-empty, pass this to the container runtime as the root cgroup.
	cgroupRoot string

	// Mounter to use for volumes.
	mounter mount.Interface

	// Writer interface to use for volumes.
	writer kubeio.Writer

	// Manager of non-Runtime containers.
	containerManager cm.ContainerManager
	nodeConfig       cm.NodeConfig

	// Whether or not kubelet should take responsibility for keeping cbr0 in
	// the correct state.
	configureCBR0 bool
	reconcileCIDR bool

	// Traffic to IPs outside this range will use IP masquerade.
	nonMasqueradeCIDR string

	// Maximum Number of Pods which can be run by this Kubelet
	maxPods int

	// Number of NVIDIA GPUs on this node
	nvidiaGPUs int

	// Monitor Kubelet's sync loop
	syncLoopMonitor atomic.Value

	// Container restart Backoff
	backOff *flowcontrol.Backoff

	// Channel for sending pods to kill.
	podKillingCh chan *kubecontainer.PodPair

	// The configuration file used as the base to generate the container's
	// DNS resolver configuration file. This can be used in conjunction with
	// clusterDomain and clusterDNS.
	resolverConfig string

	// Optionally shape the bandwidth of a pod
	// TODO: remove when kubenet plugin is ready
	shaper bandwidth.BandwidthShaper

	// True if container cpu limits should be enforced via cgroup CFS quota
	cpuCFSQuota bool

	// Information about the ports which are opened by daemons on Node running this Kubelet server.
	daemonEndpoints *api.NodeDaemonEndpoints

	// A queue used to trigger pod workers.
	workQueue queue.WorkQueue

	// oneTimeInitializer is used to initialize modules that are dependent on the runtime to be up.
	oneTimeInitializer sync.Once

	flannelExperimentalOverlay bool

	// TODO: Flannelhelper doesn't store any state, we can instantiate it
	// on the fly if we're confident the dbus connetions it opens doesn't
	// put the system under duress.
	flannelHelper *FlannelHelper

	// If non-nil, use this IP address for the node
	nodeIP net.IP

	// clock is an interface that provides time related functionality in a way that makes it
	// easy to test the code.
	clock util.Clock

	// outOfDiskTransitionFrequency specifies the amount of time the kubelet has to be actually
	// not out of disk before it can transition the node condition status from out-of-disk to
	// not-out-of-disk. This prevents a pod that causes out-of-disk condition from repeatedly
	// getting rescheduled onto the node.
	outOfDiskTransitionFrequency time.Duration

	// reservation specifies resources which are reserved for non-pod usage, including kubernetes and
	// non-kubernetes system processes.
	reservation kubetypes.Reservation

	// support gathering custom metrics.
	enableCustomMetrics bool

	// How the Kubelet should setup hairpin NAT. Can take the values: "promiscuous-bridge"
	// (make cbr0 promiscuous), "hairpin-veth" (set the hairpin flag on veth interfaces)
	// or "none" (do nothing).
	hairpinMode componentconfig.HairpinMode

	// The node has babysitter process monitoring docker and kubelet
	babysitDaemons bool

	// handlers called during the tryUpdateNodeStatus cycle
	setNodeStatusFuncs []func(*api.Node) error

	// TODO: think about moving this to be centralized in PodWorkers in follow-on.
	// the list of handlers to call during pod admission.
	lifecycle.PodAdmitHandlers

	// the list of handlers to call during pod sync loop.
	lifecycle.PodSyncLoopHandlers

	// the list of handlers to call during pod sync.
	lifecycle.PodSyncHandlers
}

// Validate given node IP belongs to the current host
func (kl *Kubelet) validateNodeIP() error {
	if kl.nodeIP == nil {
		return nil
	}

	// Honor IP limitations set in setNodeStatus()
	if kl.nodeIP.IsLoopback() {
		return fmt.Errorf("nodeIP can't be loopback address")
	}
	if kl.nodeIP.To4() == nil {
		return fmt.Errorf("nodeIP must be IPv4 address")
	}

	addrs, err := net.InterfaceAddrs()
	if err != nil {
		return err
	}
	for _, addr := range addrs {
		var ip net.IP
		switch v := addr.(type) {
		case *net.IPNet:
			ip = v.IP
		case *net.IPAddr:
			ip = v.IP
		}
		if ip != nil && ip.Equal(kl.nodeIP) {
			return nil
		}
	}
	return fmt.Errorf("Node IP: %q not found in the host's network interfaces", kl.nodeIP.String())
}

// dirExists returns true if the path exists and represents a directory.
func dirExists(path string) bool {
	s, err := os.Stat(path)
	if err != nil {
		return false
	}
	return s.IsDir()
}

// setupDataDirs creates:
// 1.  the root directory
// 2.  the pods directory
// 3.  the plugins directory
func (kl *Kubelet) setupDataDirs() error {
	kl.rootDirectory = path.Clean(kl.rootDirectory)
	if err := os.MkdirAll(kl.getRootDir(), 0750); err != nil {
		return fmt.Errorf("error creating root directory: %v", err)
	}
	if err := os.MkdirAll(kl.getPodsDir(), 0750); err != nil {
		return fmt.Errorf("error creating pods directory: %v", err)
	}
	if err := os.MkdirAll(kl.getPluginsDir(), 0750); err != nil {
		return fmt.Errorf("error creating plugins directory: %v", err)
	}
	return nil
}

// Get a list of pods that have data directories.
func (kl *Kubelet) listPodsFromDisk() ([]types.UID, error) {
	podInfos, err := ioutil.ReadDir(kl.getPodsDir())
	if err != nil {
		return nil, err
	}
	pods := []types.UID{}
	for i := range podInfos {
		if podInfos[i].IsDir() {
			pods = append(pods, types.UID(podInfos[i].Name()))
		}
	}
	return pods, nil
}

// Starts garbage collection threads.
func (kl *Kubelet) StartGarbageCollection() {
	go wait.Until(func() {
		if err := kl.containerGC.GarbageCollect(); err != nil {
			glog.Errorf("Container garbage collection failed: %v", err)
		}
	}, ContainerGCPeriod, wait.NeverStop)

	go wait.Until(func() {
		if err := kl.imageManager.GarbageCollect(); err != nil {
			glog.Errorf("Image garbage collection failed: %v", err)
		}
	}, ImageGCPeriod, wait.NeverStop)
}

// 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 {
	// Step 1: Promethues metrics.
	metrics.Register(kl.runtimeCache)

	// Step 2: Setup filesystem directories.
	if err := kl.setupDataDirs(); err != nil {
		return err
	}

	// Step 3: If the container logs directory does not exist, create it.
	if _, err := os.Stat(containerLogsDir); err != nil {
		if err := kl.os.Mkdir(containerLogsDir, 0755); err != nil {
			glog.Errorf("Failed to create directory %q: %v", containerLogsDir, err)
		}
	}

	// Step 4: Start the image manager.
	if err := kl.imageManager.Start(); err != nil {
		return fmt.Errorf("Failed to start ImageManager, images may not be garbage collected: %v", err)
	}

	// Step 5: Start container manager.
	if err := kl.containerManager.Start(); err != nil {
		return fmt.Errorf("Failed to start ContainerManager %v", err)
	}

	// Step 6: Start out of memory watcher.
	if err := kl.oomWatcher.Start(kl.nodeRef); err != nil {
		return fmt.Errorf("Failed to start OOM watcher %v", err)
	}

	// Step 7: Start resource analyzer
	kl.resourceAnalyzer.Start()

	return nil
}

// initializeRuntimeDependentModules will initialize internal modules that require the container runtime to be up.
func (kl *Kubelet) initializeRuntimeDependentModules() {
	if err := kl.cadvisor.Start(); err != nil {
		kl.runtimeState.setInternalError(fmt.Errorf("Failed to start cAdvisor %v", err))
	}
}

// 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.")
	}
	if err := kl.initializeModules(); err != nil {
		kl.recorder.Eventf(kl.nodeRef, api.EventTypeWarning, kubecontainer.KubeletSetupFailed, err.Error())
		glog.Error(err)
		kl.runtimeState.setInitError(err)
	}

	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 wait.Until(kl.syncNetworkStatus, 30*time.Second, wait.NeverStop)
	go wait.Until(kl.updateRuntimeUp, 5*time.Second, 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 the pod lifecycle event generator.
	kl.pleg.Start()
	kl.syncLoop(updates, kl)
}

// initialNodeStatus determines the initial node status, incorporating node
// labels and information from the cloud provider.
func (kl *Kubelet) initialNodeStatus() (*api.Node, error) {
	node := &api.Node{
		ObjectMeta: api.ObjectMeta{
			Name: kl.nodeName,
			Labels: map[string]string{
				unversioned.LabelHostname: kl.hostname,
				unversioned.LabelOS:       goRuntime.GOOS,
				unversioned.LabelArch:     goRuntime.GOARCH,
			},
		},
		Spec: api.NodeSpec{
			Unschedulable: !kl.registerSchedulable,
		},
	}

	// @question: should this be place after the call to the cloud provider? which also applies labels
	for k, v := range kl.nodeLabels {
		if cv, found := node.ObjectMeta.Labels[k]; found {
			glog.Warningf("the node label %s=%s will overwrite default setting %s", k, v, cv)
		}
		node.ObjectMeta.Labels[k] = v
	}

	if kl.cloud != nil {
		instances, ok := kl.cloud.Instances()
		if !ok {
			return nil, fmt.Errorf("failed to get instances from cloud provider")
		}

		// TODO(roberthbailey): Can we do this without having credentials to talk
		// to the cloud provider?
		// TODO: ExternalID is deprecated, we'll have to drop this code
		externalID, err := instances.ExternalID(kl.nodeName)
		if err != nil {
			return nil, fmt.Errorf("failed to get external ID from cloud provider: %v", err)
		}
		node.Spec.ExternalID = externalID

		// TODO: We can't assume that the node has credentials to talk to the
		// cloudprovider from arbitrary nodes. At most, we should talk to a
		// local metadata server here.
		node.Spec.ProviderID, err = cloudprovider.GetInstanceProviderID(kl.cloud, kl.nodeName)
		if err != nil {
			return nil, err
		}

		instanceType, err := instances.InstanceType(kl.nodeName)
		if err != nil {
			return nil, err
		}
		if instanceType != "" {
			glog.Infof("Adding node label from cloud provider: %s=%s", unversioned.LabelInstanceType, instanceType)
			node.ObjectMeta.Labels[unversioned.LabelInstanceType] = instanceType
		}
		// If the cloud has zone information, label the node with the zone information
		zones, ok := kl.cloud.Zones()
		if ok {
			zone, err := zones.GetZone()
			if err != nil {
				return nil, fmt.Errorf("failed to get zone from cloud provider: %v", err)
			}
			if zone.FailureDomain != "" {
				glog.Infof("Adding node label from cloud provider: %s=%s", unversioned.LabelZoneFailureDomain, zone.FailureDomain)
				node.ObjectMeta.Labels[unversioned.LabelZoneFailureDomain] = zone.FailureDomain
			}
			if zone.Region != "" {
				glog.Infof("Adding node label from cloud provider: %s=%s", unversioned.LabelZoneRegion, zone.Region)
				node.ObjectMeta.Labels[unversioned.LabelZoneRegion] = zone.Region
			}
		}
	} else {
		node.Spec.ExternalID = kl.hostname
	}
	if err := kl.setNodeStatus(node); err != nil {
		return nil, err
	}
	return node, nil
}

// registerWithApiserver registers the node with the cluster master. It is safe
// to call multiple times, but not concurrently (kl.registrationCompleted is
// not locked).
func (kl *Kubelet) registerWithApiserver() {
	if kl.registrationCompleted {
		return
	}
	step := 100 * time.Millisecond
	for {
		time.Sleep(step)
		step = step * 2
		if step >= 7*time.Second {
			step = 7 * time.Second
		}

		node, err := kl.initialNodeStatus()
		if err != nil {
			glog.Errorf("Unable to construct api.Node object for kubelet: %v", err)
			continue
		}
		glog.V(2).Infof("Attempting to register node %s", node.Name)
		if _, err := kl.kubeClient.Core().Nodes().Create(node); err != nil {
			if !apierrors.IsAlreadyExists(err) {
				glog.V(2).Infof("Unable to register %s with the apiserver: %v", node.Name, err)
				continue
			}
			currentNode, err := kl.kubeClient.Core().Nodes().Get(kl.nodeName)
			if err != nil {
				glog.Errorf("error getting node %q: %v", kl.nodeName, err)
				continue
			}
			if currentNode == nil {
				glog.Errorf("no node instance returned for %q", kl.nodeName)
				continue
			}
			if currentNode.Spec.ExternalID == node.Spec.ExternalID {
				glog.Infof("Node %s was previously registered", node.Name)
				kl.registrationCompleted = true
				return
			}
			glog.Errorf(
				"Previously %q had externalID %q; now it is %q; will delete and recreate.",
				kl.nodeName, node.Spec.ExternalID, currentNode.Spec.ExternalID,
			)
			if err := kl.kubeClient.Core().Nodes().Delete(node.Name, nil); err != nil {
				glog.Errorf("Unable to delete old node: %v", err)
			} else {
				glog.Errorf("Deleted old node object %q", kl.nodeName)
			}
			continue
		}
		glog.Infof("Successfully registered node %s", node.Name)
		kl.registrationCompleted = true
		return
	}
}

// syncNodeStatus should be called periodically from a goroutine.
// It synchronizes node status to master, registering the kubelet first if
// necessary.
func (kl *Kubelet) syncNodeStatus() {
	if kl.kubeClient == nil {
		return
	}
	if kl.registerNode {
		// This will exit immediately if it doesn't need to do anything.
		kl.registerWithApiserver()
	}
	if err := kl.updateNodeStatus(); err != nil {
		glog.Errorf("Unable to update node status: %v", err)
	}
}

// relabelVolumes relabels SELinux volumes to match the pod's
// SELinuxOptions specification. This is only needed if the pod uses
// hostPID or hostIPC. Otherwise relabeling is delegated to docker.
func (kl *Kubelet) relabelVolumes(pod *api.Pod, volumes kubecontainer.VolumeMap) error {
	if pod.Spec.SecurityContext.SELinuxOptions == nil {
		return nil
	}

	rootDirContext, err := kl.getRootDirContext()
	if err != nil {
		return err
	}

	chconRunner := selinux.NewChconRunner()
	// Apply the pod's Level to the rootDirContext
	rootDirSELinuxOptions, err := securitycontext.ParseSELinuxOptions(rootDirContext)
	if err != nil {
		return err
	}

	rootDirSELinuxOptions.Level = pod.Spec.SecurityContext.SELinuxOptions.Level
	volumeContext := fmt.Sprintf("%s:%s:%s:%s", rootDirSELinuxOptions.User, rootDirSELinuxOptions.Role, rootDirSELinuxOptions.Type, rootDirSELinuxOptions.Level)

	for _, vol := range volumes {
		if vol.Mounter.GetAttributes().Managed && vol.Mounter.GetAttributes().SupportsSELinux {
			// Relabel the volume and its content to match the 'Level' of the pod
			err := filepath.Walk(vol.Mounter.GetPath(), func(path string, info os.FileInfo, err error) error {
				if err != nil {
					return err
				}
				return chconRunner.SetContext(path, volumeContext)
			})
			if err != nil {
				return err
			}
			vol.SELinuxLabeled = true
		}
	}
	return nil
}

// makeMounts determines the mount points for the given container.
func makeMounts(pod *api.Pod, podDir string, container *api.Container, hostName, hostDomain, podIP string, podVolumes kubecontainer.VolumeMap) ([]kubecontainer.Mount, error) {
	// Kubernetes only mounts on /etc/hosts if :
	// - container does not use hostNetwork and
	// - container is not a infrastructure(pause) container
	// - container is not already mounting on /etc/hosts
	// When the pause container is being created, its IP is still unknown. Hence, PodIP will not have been set.
	mountEtcHostsFile := (pod.Spec.SecurityContext == nil || !pod.Spec.SecurityContext.HostNetwork) && len(podIP) > 0
	glog.V(3).Infof("container: %v/%v/%v podIP: %q creating hosts mount: %v", pod.Namespace, pod.Name, container.Name, podIP, mountEtcHostsFile)
	mounts := []kubecontainer.Mount{}
	for _, mount := range container.VolumeMounts {
		mountEtcHostsFile = mountEtcHostsFile && (mount.MountPath != etcHostsPath)
		vol, ok := podVolumes[mount.Name]
		if !ok {
			glog.Warningf("Mount cannot be satisified for container %q, because the volume is missing: %q", container.Name, mount)
			continue
		}

		relabelVolume := false
		// If the volume supports SELinux and it has not been
		// relabeled already and it is not a read-only volume,
		// relabel it and mark it as labeled
		if vol.Mounter.GetAttributes().Managed && vol.Mounter.GetAttributes().SupportsSELinux && !vol.SELinuxLabeled {
			vol.SELinuxLabeled = true
			relabelVolume = true
		}
		hostPath := vol.Mounter.GetPath()
		if mount.SubPath != "" {
			hostPath = filepath.Join(hostPath, mount.SubPath)
		}
		mounts = append(mounts, kubecontainer.Mount{
			Name:           mount.Name,
			ContainerPath:  mount.MountPath,
			HostPath:       hostPath,
			ReadOnly:       mount.ReadOnly,
			SELinuxRelabel: relabelVolume,
		})
	}
	if mountEtcHostsFile {
		hostsMount, err := makeHostsMount(podDir, podIP, hostName, hostDomain)
		if err != nil {
			return nil, err
		}
		mounts = append(mounts, *hostsMount)
	}
	return mounts, nil
}

// makeHostsMount makes the mountpoint for the hosts file that the containers
// in a pod are injected with.
func makeHostsMount(podDir, podIP, hostName, hostDomainName string) (*kubecontainer.Mount, error) {
	hostsFilePath := path.Join(podDir, "etc-hosts")
	if err := ensureHostsFile(hostsFilePath, podIP, hostName, hostDomainName); err != nil {
		return nil, err
	}
	return &kubecontainer.Mount{
		Name:          "k8s-managed-etc-hosts",
		ContainerPath: etcHostsPath,
		HostPath:      hostsFilePath,
		ReadOnly:      false,
	}, nil
}

// ensureHostsFile ensures that the given host file has an up-to-date ip, host
// name, and domain name.
func ensureHostsFile(fileName, hostIP, hostName, hostDomainName string) error {
	if _, err := os.Stat(fileName); os.IsExist(err) {
		glog.V(4).Infof("kubernetes-managed etc-hosts file exits. Will not be recreated: %q", fileName)
		return nil
	}
	var buffer bytes.Buffer
	buffer.WriteString("# Kubernetes-managed hosts file.\n")
	buffer.WriteString("127.0.0.1\tlocalhost\n")                      // ipv4 localhost
	buffer.WriteString("::1\tlocalhost ip6-localhost ip6-loopback\n") // ipv6 localhost
	buffer.WriteString("fe00::0\tip6-localnet\n")
	buffer.WriteString("fe00::0\tip6-mcastprefix\n")
	buffer.WriteString("fe00::1\tip6-allnodes\n")
	buffer.WriteString("fe00::2\tip6-allrouters\n")
	if len(hostDomainName) > 0 {
		buffer.WriteString(fmt.Sprintf("%s\t%s.%s\t%s\n", hostIP, hostName, hostDomainName, hostName))
	} else {
		buffer.WriteString(fmt.Sprintf("%s\t%s\n", hostIP, hostName))
	}
	return ioutil.WriteFile(fileName, buffer.Bytes(), 0644)
}

func makePortMappings(container *api.Container) (ports []kubecontainer.PortMapping) {
	names := make(map[string]struct{})
	for _, p := range container.Ports {
		pm := kubecontainer.PortMapping{
			HostPort:      int(p.HostPort),
			ContainerPort: int(p.ContainerPort),
			Protocol:      p.Protocol,
			HostIP:        p.HostIP,
		}

		// We need to create some default port name if it's not specified, since
		// this is necessary for rkt.
		// http://issue.k8s.io/7710
		if p.Name == "" {
			pm.Name = fmt.Sprintf("%s-%s:%d", container.Name, p.Protocol, p.ContainerPort)
		} else {
			pm.Name = fmt.Sprintf("%s-%s", container.Name, p.Name)
		}

		// Protect against exposing the same protocol-port more than once in a container.
		if _, ok := names[pm.Name]; ok {
			glog.Warningf("Port name conflicted, %q is defined more than once", pm.Name)
			continue
		}
		ports = append(ports, pm)
		names[pm.Name] = struct{}{}
	}
	return
}

func (kl *Kubelet) GeneratePodHostNameAndDomain(pod *api.Pod) (string, string, error) {
	// TODO(vmarmol): Handle better.
	// Cap hostname at 63 chars (specification is 64bytes which is 63 chars and the null terminating char).
	clusterDomain := kl.clusterDomain
	const hostnameMaxLen = 63
	podAnnotations := pod.Annotations
	if podAnnotations == nil {
		podAnnotations = make(map[string]string)
	}
	hostname := pod.Name
	if len(pod.Spec.Hostname) > 0 {
		if utilvalidation.IsDNS1123Label(pod.Spec.Hostname) {
			hostname = pod.Spec.Hostname
		} else {
			return "", "", fmt.Errorf("Pod Hostname %q is not a valid DNS label.", pod.Spec.Hostname)
		}
	} else {
		hostnameCandidate := podAnnotations[utilpod.PodHostnameAnnotation]
		if utilvalidation.IsDNS1123Label(hostnameCandidate) {
			// use hostname annotation, if specified.
			hostname = hostnameCandidate
		}
	}
	if len(hostname) > hostnameMaxLen {
		hostname = hostname[:hostnameMaxLen]
		glog.Errorf("hostname for pod:%q was longer than %d. Truncated hostname to :%q", pod.Name, hostnameMaxLen, hostname)
	}

	hostDomain := ""
	if len(pod.Spec.Subdomain) > 0 {
		if utilvalidation.IsDNS1123Label(pod.Spec.Subdomain) {
			hostDomain = fmt.Sprintf("%s.%s.svc.%s", pod.Spec.Subdomain, pod.Namespace, clusterDomain)
		} else {
			return "", "", fmt.Errorf("Pod Subdomain %q is not a valid DNS label.", pod.Spec.Subdomain)
		}
	} else {
		subdomainCandidate := pod.Annotations[utilpod.PodSubdomainAnnotation]
		if utilvalidation.IsDNS1123Label(subdomainCandidate) {
			hostDomain = fmt.Sprintf("%s.%s.svc.%s", subdomainCandidate, pod.Namespace, clusterDomain)
		}
	}
	return hostname, hostDomain, nil
}

// GenerateRunContainerOptions generates the RunContainerOptions, which can be used by
// the container runtime to set parameters for launching a container.
func (kl *Kubelet) GenerateRunContainerOptions(pod *api.Pod, container *api.Container, podIP string) (*kubecontainer.RunContainerOptions, error) {
	var err error
	opts := &kubecontainer.RunContainerOptions{CgroupParent: kl.cgroupRoot}
	hostname, hostDomainName, err := kl.GeneratePodHostNameAndDomain(pod)
	if err != nil {
		return nil, err
	}
	opts.Hostname = hostname
	vol, ok := kl.volumeManager.GetVolumes(pod.UID)
	if !ok {
		return nil, fmt.Errorf("impossible: cannot find the mounted volumes for pod %q", format.Pod(pod))
	}

	opts.PortMappings = makePortMappings(container)
	// Docker does not relabel volumes if the container is running
	// in the host pid or ipc namespaces so the kubelet must
	// relabel the volumes
	if pod.Spec.SecurityContext != nil && (pod.Spec.SecurityContext.HostIPC || pod.Spec.SecurityContext.HostPID) {
		err = kl.relabelVolumes(pod, vol)
		if err != nil {
			return nil, err
		}
	}

	opts.Mounts, err = makeMounts(pod, kl.getPodDir(pod.UID), container, hostname, hostDomainName, podIP, vol)
	if err != nil {
		return nil, err
	}
	opts.Envs, err = kl.makeEnvironmentVariables(pod, container, podIP)
	if err != nil {
		return nil, err
	}

	if len(container.TerminationMessagePath) != 0 {
		p := kl.getPodContainerDir(pod.UID, container.Name)
		if err := os.MkdirAll(p, 0750); err != nil {
			glog.Errorf("Error on creating %q: %v", p, err)
		} else {
			opts.PodContainerDir = p
		}
	}

	opts.DNS, opts.DNSSearch, err = kl.GetClusterDNS(pod)
	if err != nil {
		return nil, err
	}

	return opts, nil
}

var masterServices = sets.NewString("kubernetes")

// getServiceEnvVarMap makes a map[string]string of env vars for services a pod in namespace ns should see
func (kl *Kubelet) getServiceEnvVarMap(ns string) (map[string]string, error) {
	var (
		serviceMap = make(map[string]api.Service)
		m          = make(map[string]string)
	)

	// Get all service resources from the master (via a cache),
	// and populate them into service environment variables.
	if kl.serviceLister == nil {
		// Kubelets without masters (e.g. plain GCE ContainerVM) don't set env vars.
		return m, nil
	}
	services, err := kl.serviceLister.List()
	if err != nil {
		return m, fmt.Errorf("failed to list services when setting up env vars.")
	}

	// project the services in namespace ns onto the master services
	for _, service := range services.Items {
		// ignore services where ClusterIP is "None" or empty
		if !api.IsServiceIPSet(&service) {
			continue
		}
		serviceName := service.Name

		switch service.Namespace {
		// for the case whether the master service namespace is the namespace the pod
		// is in, the pod should receive all the services in the namespace.
		//
		// ordering of the case clauses below enforces this
		case ns:
			serviceMap[serviceName] = service
		case kl.masterServiceNamespace:
			if masterServices.Has(serviceName) {
				if _, exists := serviceMap[serviceName]; !exists {
					serviceMap[serviceName] = service
				}
			}
		}
	}
	services.Items = []api.Service{}
	for _, service := range serviceMap {
		services.Items = append(services.Items, service)
	}

	for _, e := range envvars.FromServices(&services) {
		m[e.Name] = e.Value
	}
	return m, nil
}

// Make the environment variables for a pod in the given namespace.
func (kl *Kubelet) makeEnvironmentVariables(pod *api.Pod, container *api.Container, podIP string) ([]kubecontainer.EnvVar, error) {
	var result []kubecontainer.EnvVar
	// Note:  These are added to the docker Config, but are not included in the checksum computed
	// by dockertools.BuildDockerName(...).  That way, we can still determine whether an
	// api.Container is already running by its hash. (We don't want to restart a container just
	// because some service changed.)
	//
	// Note that there is a race between Kubelet seeing the pod and kubelet seeing the service.
	// To avoid this users can: (1) wait between starting a service and starting; or (2) detect
	// missing service env var and exit and be restarted; or (3) use DNS instead of env vars
	// and keep trying to resolve the DNS name of the service (recommended).
	serviceEnv, err := kl.getServiceEnvVarMap(pod.Namespace)
	if err != nil {
		return result, err
	}

	// Determine the final values of variables:
	//
	// 1.  Determine the final value of each variable:
	//     a.  If the variable's Value is set, expand the `$(var)` references to other
	//         variables in the .Value field; the sources of variables are the declared
	//         variables of the container and the service environment variables
	//     b.  If a source is defined for an environment variable, resolve the source
	// 2.  Create the container's environment in the order variables are declared
	// 3.  Add remaining service environment vars
	var (
		tmpEnv      = make(map[string]string)
		configMaps  = make(map[string]*api.ConfigMap)
		secrets     = make(map[string]*api.Secret)
		mappingFunc = expansion.MappingFuncFor(tmpEnv, serviceEnv)
	)
	for _, envVar := range container.Env {
		// Accesses apiserver+Pods.
		// So, the master may set service env vars, or kubelet may.  In case both are doing
		// it, we delete the key from the kubelet-generated ones so we don't have duplicate
		// env vars.
		// TODO: remove this net line once all platforms use apiserver+Pods.
		delete(serviceEnv, envVar.Name)

		runtimeVal := envVar.Value
		if runtimeVal != "" {
			// Step 1a: expand variable references
			runtimeVal = expansion.Expand(runtimeVal, mappingFunc)
		} else if envVar.ValueFrom != nil {
			// Step 1b: resolve alternate env var sources
			switch {
			case envVar.ValueFrom.FieldRef != nil:
				runtimeVal, err = kl.podFieldSelectorRuntimeValue(envVar.ValueFrom.FieldRef, pod, podIP)
				if err != nil {
					return result, err
				}
			case envVar.ValueFrom.ConfigMapKeyRef != nil:
				name := envVar.ValueFrom.ConfigMapKeyRef.Name
				key := envVar.ValueFrom.ConfigMapKeyRef.Key
				configMap, ok := configMaps[name]
				if !ok {
					configMap, err = kl.kubeClient.Core().ConfigMaps(pod.Namespace).Get(name)
					if err != nil {
						return result, err
					}
				}
				runtimeVal, ok = configMap.Data[key]
				if !ok {
					return result, fmt.Errorf("Couldn't find key %v in ConfigMap %v/%v", key, pod.Namespace, name)
				}
			case envVar.ValueFrom.SecretKeyRef != nil:
				name := envVar.ValueFrom.SecretKeyRef.Name
				key := envVar.ValueFrom.SecretKeyRef.Key
				secret, ok := secrets[name]
				if !ok {
					secret, err = kl.kubeClient.Core().Secrets(pod.Namespace).Get(name)
					if err != nil {
						return result, err
					}
				}
				runtimeValBytes, ok := secret.Data[key]
				if !ok {
					return result, fmt.Errorf("Couldn't find key %v in Secret %v/%v", key, pod.Namespace, name)
				}
				runtimeVal = string(runtimeValBytes)
			}
		}

		tmpEnv[envVar.Name] = runtimeVal
		result = append(result, kubecontainer.EnvVar{Name: envVar.Name, Value: tmpEnv[envVar.Name]})
	}

	// Append remaining service env vars.
	for k, v := range serviceEnv {
		result = append(result, kubecontainer.EnvVar{Name: k, Value: v})
	}
	return result, nil
}

// podFieldSelectorRuntimeValue returns the runtime value of the given
// selector for a pod.
func (kl *Kubelet) podFieldSelectorRuntimeValue(fs *api.ObjectFieldSelector, pod *api.Pod, podIP string) (string, error) {
	internalFieldPath, _, err := api.Scheme.ConvertFieldLabel(fs.APIVersion, "Pod", fs.FieldPath, "")
	if err != nil {
		return "", err
	}
	switch internalFieldPath {
	case "status.podIP":
		return podIP, nil
	}
	return fieldpath.ExtractFieldPathAsString(pod, internalFieldPath)
}

// GetClusterDNS returns a list of the DNS servers and a list of the DNS search
// domains of the cluster.
func (kl *Kubelet) GetClusterDNS(pod *api.Pod) ([]string, []string, error) {
	var hostDNS, hostSearch []string
	// Get host DNS settings
	if kl.resolverConfig != "" {
		f, err := os.Open(kl.resolverConfig)
		if err != nil {
			return nil, nil, err
		}
		defer f.Close()

		hostDNS, hostSearch, err = kl.parseResolvConf(f)
		if err != nil {
			return nil, nil, err
		}
	}
	useClusterFirstPolicy := pod.Spec.DNSPolicy == api.DNSClusterFirst
	if useClusterFirstPolicy && kl.clusterDNS == nil {
		// clusterDNS is not known.
		// pod with ClusterDNSFirst Policy cannot be created
		kl.recorder.Eventf(pod, api.EventTypeWarning, "MissingClusterDNS", "kubelet does not have ClusterDNS IP configured and cannot create Pod using %q policy. Falling back to DNSDefault policy.", pod.Spec.DNSPolicy)
		log := fmt.Sprintf("kubelet does not have ClusterDNS IP configured and cannot create Pod using %q policy. pod: %q. Falling back to DNSDefault policy.", pod.Spec.DNSPolicy, format.Pod(pod))
		kl.recorder.Eventf(kl.nodeRef, api.EventTypeWarning, "MissingClusterDNS", log)

		// fallback to DNSDefault
		useClusterFirstPolicy = false
	}

	if !useClusterFirstPolicy {
		// When the kubelet --resolv-conf flag is set to the empty string, use
		// DNS settings that override the docker default (which is to use
		// /etc/resolv.conf) and effectivly disable DNS lookups. According to
		// the bind documentation, the behavior of the DNS client library when
		// "nameservers" are not specified is to "use the nameserver on the
		// local machine". A nameserver setting of localhost is equivalent to
		// this documented behavior.
		if kl.resolverConfig == "" {
			hostDNS = []string{"127.0.0.1"}
			hostSearch = []string{"."}
		}
		return hostDNS, hostSearch, nil
	}

	// for a pod with DNSClusterFirst policy, the cluster DNS server is the only nameserver configured for
	// the pod. The cluster DNS server itself will forward queries to other nameservers that is configured to use,
	// in case the cluster DNS server cannot resolve the DNS query itself
	dns := []string{kl.clusterDNS.String()}

	var dnsSearch []string
	if kl.clusterDomain != "" {
		nsSvcDomain := fmt.Sprintf("%s.svc.%s", pod.Namespace, kl.clusterDomain)
		svcDomain := fmt.Sprintf("svc.%s", kl.clusterDomain)
		dnsSearch = append([]string{nsSvcDomain, svcDomain, kl.clusterDomain}, hostSearch...)
	} else {
		dnsSearch = hostSearch
	}
	return dns, dnsSearch, nil
}

// Returns the list of DNS servers and DNS search domains.
func (kl *Kubelet) parseResolvConf(reader io.Reader) (nameservers []string, searches []string, err error) {
	var scrubber dnsScrubber
	if kl.cloud != nil {
		scrubber = kl.cloud
	}
	return parseResolvConf(reader, scrubber)
}

// A helper for testing.
type dnsScrubber interface {
	ScrubDNS(nameservers, searches []string) (nsOut, srchOut []string)
}

// parseResolveConf reads a resolv.conf file from the given reader, and parses
// it into nameservers and searches, possibly returning an error.  The given
// dnsScrubber allows cloud providers to post-process dns names.
// TODO: move to utility package
func parseResolvConf(reader io.Reader, dnsScrubber dnsScrubber) (nameservers []string, searches []string, err error) {
	file, err := ioutil.ReadAll(reader)
	if err != nil {
		return nil, nil, err
	}

	// Lines of the form "nameserver 1.2.3.4" accumulate.
	nameservers = []string{}

	// Lines of the form "search example.com" overrule - last one wins.
	searches = []string{}

	lines := strings.Split(string(file), "\n")
	for l := range lines {
		trimmed := strings.TrimSpace(lines[l])
		if strings.HasPrefix(trimmed, "#") {
			continue
		}
		fields := strings.Fields(trimmed)
		if len(fields) == 0 {
			continue
		}
		if fields[0] == "nameserver" {
			nameservers = append(nameservers, fields[1:]...)
		}
		if fields[0] == "search" {
			searches = fields[1:]
		}
	}

	// Give the cloud-provider a chance to post-process DNS settings.
	if dnsScrubber != nil {
		nameservers, searches = dnsScrubber.ScrubDNS(nameservers, searches)
	}
	return nameservers, searches, nil
}

// One of the following aruguements must be non-nil: runningPod, status.
// TODO: Modify containerRuntime.KillPod() to accept the right arguments.
func (kl *Kubelet) killPod(pod *api.Pod, runningPod *kubecontainer.Pod, status *kubecontainer.PodStatus, gracePeriodOverride *int64) error {
	var p kubecontainer.Pod
	if runningPod != nil {
		p = *runningPod
	} else if status != nil {
		p = kubecontainer.ConvertPodStatusToRunningPod(status)
	}
	return kl.containerRuntime.KillPod(pod, p, gracePeriodOverride)
}

// makePodDataDirs creates the dirs for the pod datas.
func (kl *Kubelet) makePodDataDirs(pod *api.Pod) error {
	uid := pod.UID
	if err := os.Mkdir(kl.getPodDir(uid), 0750); err != nil && !os.IsExist(err) {
		return err
	}
	if err := os.Mkdir(kl.getPodVolumesDir(uid), 0750); err != nil && !os.IsExist(err) {
		return err
	}
	if err := os.Mkdir(kl.getPodPluginsDir(uid), 0750); err != nil && !os.IsExist(err) {
		return err
	}
	return nil
}

// syncPod is the transaction script for the sync of a single pod.
//
// Arguments:
//
// pod - the pod to sync
// mirrorPod - the mirror pod for the pod to sync, if it is a static pod
// podStatus - the current status (TODO: always from the status manager?)
// updateType - the type of update (ADD, UPDATE, REMOVE, RECONCILE)
//
// The workflow is:
// * If the pod is being created, record pod worker start latency
// * Call generateAPIPodStatus to prepare an api.PodStatus for the pod
// * If the pod is being seen as running for the first time, record pod
//   start latency
// * Update the status of the pod in the status manager
// * Kill the pod if it should not be running
// * Create a mirror pod if the pod is a static pod, and does not
//   already have a mirror pod
// * Create the data directories for the pod if they do not exist
// * Mount volumes and update the volume manager
// * Fetch the pull secrets for the pod
// * Call the container runtime's SyncPod callback
// * Update the traffic shaping for the pod's ingress and egress limits
//
// If any step if this workflow errors, the error is returned, and is repeated
// on the next syncPod call.
func (kl *Kubelet) syncPod(o syncPodOptions) error {
	// pull out the required options
	pod := o.pod
	mirrorPod := o.mirrorPod
	podStatus := o.podStatus
	updateType := o.updateType

	// if we want to kill a pod, do it now!
	if updateType == kubetypes.SyncPodKill {
		killPodOptions := o.killPodOptions
		if killPodOptions == nil || killPodOptions.PodStatusFunc == nil {
			return fmt.Errorf("kill pod options are required if update type is kill")
		}
		apiPodStatus := killPodOptions.PodStatusFunc(pod, podStatus)
		kl.statusManager.SetPodStatus(pod, apiPodStatus)
		// we kill the pod with the specified grace period since this is a termination
		if err := kl.killPod(pod, nil, podStatus, killPodOptions.PodTerminationGracePeriodSecondsOverride); err != nil {
			// there was an error killing the pod, so we return that error directly
			utilruntime.HandleError(err)
			return err
		}
		return nil
	}

	// Latency measurements for the main workflow are relative to the
	// (first time the pod was seen by the API server.
	var firstSeenTime time.Time
	if firstSeenTimeStr, ok := pod.Annotations[kubetypes.ConfigFirstSeenAnnotationKey]; ok {
		firstSeenTime = kubetypes.ConvertToTimestamp(firstSeenTimeStr).Get()
	}

	// Record pod worker start latency if being created
	// TODO: make pod workers record their own latencies
	if updateType == kubetypes.SyncPodCreate {
		if !firstSeenTime.IsZero() {
			// This is the first time we are syncing the pod. Record the latency
			// since kubelet first saw the pod if firstSeenTime is set.
			metrics.PodWorkerStartLatency.Observe(metrics.SinceInMicroseconds(firstSeenTime))
		} else {
			glog.V(3).Infof("First seen time not recorded for pod %q", pod.UID)
		}
	}

	// Generate final API pod status with pod and status manager status
	apiPodStatus := kl.generateAPIPodStatus(pod, podStatus)
	// The pod IP may be changed in generateAPIPodStatus if the pod is using host network. (See #24576)
	// TODO(random-liu): After writing pod spec into container labels, check whether pod is using host network, and
	// set pod IP to hostIP directly in runtime.GetPodStatus
	podStatus.IP = apiPodStatus.PodIP

	// Record the time it takes for the pod to become running.
	existingStatus, ok := kl.statusManager.GetPodStatus(pod.UID)
	if !ok || existingStatus.Phase == api.PodPending && apiPodStatus.Phase == api.PodRunning &&
		!firstSeenTime.IsZero() {
		metrics.PodStartLatency.Observe(metrics.SinceInMicroseconds(firstSeenTime))
	}
	// Update status in the status manager
	kl.statusManager.SetPodStatus(pod, apiPodStatus)

	// Kill pod if it should not be running
	if err := canRunPod(pod); err != nil || pod.DeletionTimestamp != nil || apiPodStatus.Phase == api.PodFailed {
		if err := kl.killPod(pod, nil, podStatus, nil); err != nil {
			// there was an error killing the pod, so we return that error directly
			utilruntime.HandleError(err)
			return err
		}
		// there was no error killing the pod, but the pod cannot be run, so we return that err (if any)
		return err
	}

	// Create Mirror Pod for Static Pod if it doesn't already exist
	if kubepod.IsStaticPod(pod) {
		podFullName := kubecontainer.GetPodFullName(pod)
		deleted := false
		if mirrorPod != nil {
			if mirrorPod.DeletionTimestamp != nil || !kl.podManager.IsMirrorPodOf(mirrorPod, pod) {
				// The mirror pod is semantically different from the static pod. Remove
				// it. The mirror pod will get recreated later.
				glog.Errorf("Deleting mirror pod %q because it is outdated", format.Pod(mirrorPod))
				if err := kl.podManager.DeleteMirrorPod(podFullName); err != nil {
					glog.Errorf("Failed deleting mirror pod %q: %v", format.Pod(mirrorPod), err)
				} else {
					deleted = true
				}
			}
		}
		if mirrorPod == nil || deleted {
			glog.V(3).Infof("Creating a mirror pod for static pod %q", format.Pod(pod))
			if err := kl.podManager.CreateMirrorPod(pod); err != nil {
				glog.Errorf("Failed creating a mirror pod for %q: %v", format.Pod(pod), err)
			}
		}
	}

	// Make data directories for the pod
	if err := kl.makePodDataDirs(pod); err != nil {
		glog.Errorf("Unable to make pod data directories for pod %q: %v", format.Pod(pod), err)
		return err
	}

	// Mount volumes and update the volume manager
	podVolumes, err := kl.mountExternalVolumes(pod)
	if err != nil {
		ref, errGetRef := api.GetReference(pod)
		if errGetRef == nil && ref != nil {
			kl.recorder.Eventf(ref, api.EventTypeWarning, kubecontainer.FailedMountVolume, "Unable to mount volumes for pod %q: %v", format.Pod(pod), err)
			glog.Errorf("Unable to mount volumes for pod %q: %v; skipping pod", format.Pod(pod), err)
			return err
		}
	}
	kl.volumeManager.SetVolumes(pod.UID, podVolumes)

	// Fetch the pull secrets for the pod
	pullSecrets, err := kl.getPullSecretsForPod(pod)
	if err != nil {
		glog.Errorf("Unable to get pull secrets for pod %q: %v", format.Pod(pod), err)
		return err
	}

	// Call the container runtime's SyncPod callback
	result := kl.containerRuntime.SyncPod(pod, apiPodStatus, podStatus, pullSecrets, kl.backOff)
	kl.reasonCache.Update(pod.UID, result)
	if err = result.Error(); err != nil {
		return err
	}

	// early successful exit if pod is not bandwidth-constrained
	if !kl.shapingEnabled() {
		return nil
	}

	// Update the traffic shaping for the pod's ingress and egress limits
	ingress, egress, err := bandwidth.ExtractPodBandwidthResources(pod.Annotations)
	if err != nil {
		return err
	}
	if egress != nil || ingress != nil {
		if podUsesHostNetwork(pod) {
			kl.recorder.Event(pod, api.EventTypeWarning, kubecontainer.HostNetworkNotSupported, "Bandwidth shaping is not currently supported on the host network")
		} else if kl.shaper != nil {
			if len(apiPodStatus.PodIP) > 0 {
				err = kl.shaper.ReconcileCIDR(fmt.Sprintf("%s/32", apiPodStatus.PodIP), egress, ingress)
			}
		} else {
			kl.recorder.Event(pod, api.EventTypeWarning, kubecontainer.UndefinedShaper, "Pod requests bandwidth shaping, but the shaper is undefined")
		}
	}

	return nil
}

// returns whether the pod uses the host network namespace.
func podUsesHostNetwork(pod *api.Pod) bool {
	return pod.Spec.SecurityContext != nil && pod.Spec.SecurityContext.HostNetwork
}

// getPullSecretsForPod inspects the Pod and retrieves the referenced pull secrets
// TODO duplicate secrets are being retrieved multiple times and there is no cache.  Creating and using a secret manager interface will make this easier to address.
func (kl *Kubelet) getPullSecretsForPod(pod *api.Pod) ([]api.Secret, error) {
	pullSecrets := []api.Secret{}

	for _, secretRef := range pod.Spec.ImagePullSecrets {
		secret, err := kl.kubeClient.Core().Secrets(pod.Namespace).Get(secretRef.Name)
		if err != nil {
			glog.Warningf("Unable to retrieve pull secret %s/%s for %s/%s due to %v.  The image pull may not succeed.", pod.Namespace, secretRef.Name, pod.Namespace, pod.Name, err)
			continue
		}

		pullSecrets = append(pullSecrets, *secret)
	}

	return pullSecrets, nil
}

// resolveVolumeName returns the name of the persistent volume (PV) claimed by
// a persistent volume claim (PVC) or an error if the claim is not bound.
// Returns nil if the volume does not use a PVC.
func (kl *Kubelet) resolveVolumeName(pod *api.Pod, volume *api.Volume) (string, error) {
	claimSource := volume.VolumeSource.PersistentVolumeClaim
	if claimSource != nil {
		// resolve real volume behind the claim
		claim, err := kl.kubeClient.Core().PersistentVolumeClaims(pod.Namespace).Get(claimSource.ClaimName)
		if err != nil {
			return "", fmt.Errorf("Cannot find claim %s/%s for volume %s", pod.Namespace, claimSource.ClaimName, volume.Name)
		}
		if claim.Status.Phase != api.ClaimBound {
			return "", fmt.Errorf("Claim for volume %s/%s is not bound yet", pod.Namespace, claimSource.ClaimName)
		}
		// Use the real bound volume instead of PersistentVolume.Name
		return claim.Spec.VolumeName, nil
	}
	return volume.Name, nil
}

// Stores all volumes defined by the set of pods into a map.
// It stores real volumes there, i.e. persistent volume claims are resolved
// to volumes that are bound to them.
// Keys for each entry are in the format (POD_ID)/(VOLUME_NAME)
func (kl *Kubelet) getDesiredVolumes(pods []*api.Pod) map[string]api.Volume {
	desiredVolumes := make(map[string]api.Volume)
	for _, pod := range pods {
		for _, volume := range pod.Spec.Volumes {
			volumeName, err := kl.resolveVolumeName(pod, &volume)
			if err != nil {
				glog.V(3).Infof("%v", err)
				// Ignore the error and hope it's resolved next time
				continue
			}
			identifier := path.Join(string(pod.UID), volumeName)
			desiredVolumes[identifier] = volume
		}
	}
	return desiredVolumes
}

// cleanupOrphanedPodDirs removes the volumes of pods that should not be
// running and that have no containers running.
func (kl *Kubelet) cleanupOrphanedPodDirs(pods []*api.Pod, runningPods []*kubecontainer.Pod) error {
	active := sets.NewString()
	for _, pod := range pods {
		active.Insert(string(pod.UID))
	}
	for _, pod := range runningPods {
		active.Insert(string(pod.ID))
	}

	found, err := kl.listPodsFromDisk()
	if err != nil {
		return err
	}
	errlist := []error{}
	for _, uid := range found {
		if active.Has(string(uid)) {
			continue
		}
		if volumes, err := kl.getPodVolumes(uid); err != nil || len(volumes) != 0 {
			glog.V(3).Infof("Orphaned pod %q found, but volumes are not cleaned up; err: %v, volumes: %v ", uid, err, volumes)
			continue
		}

		glog.V(3).Infof("Orphaned pod %q found, removing", uid)
		if err := os.RemoveAll(kl.getPodDir(uid)); err != nil {
			errlist = append(errlist, err)
		}
	}
	return utilerrors.NewAggregate(errlist)
}

// cleanupBandwidthLimits updates the status of bandwidth-limited containers
// and ensures that only the the appropriate CIDRs are active on the node.
func (kl *Kubelet) cleanupBandwidthLimits(allPods []*api.Pod) error {
	if kl.shaper == nil {
		return nil
	}
	currentCIDRs, err := kl.shaper.GetCIDRs()
	if err != nil {
		return err
	}
	possibleCIDRs := sets.String{}
	for ix := range allPods {
		pod := allPods[ix]
		ingress, egress, err := bandwidth.ExtractPodBandwidthResources(pod.Annotations)
		if err != nil {
			return err
		}
		if ingress == nil && egress == nil {
			glog.V(8).Infof("Not a bandwidth limited container...")
			continue
		}
		status, found := kl.statusManager.GetPodStatus(pod.UID)
		if !found {
			// TODO(random-liu): Cleanup status get functions. (issue #20477)
			s, err := kl.containerRuntime.GetPodStatus(pod.UID, pod.Name, pod.Namespace)
			if err != nil {
				return err
			}
			status = kl.generateAPIPodStatus(pod, s)
		}
		if status.Phase == api.PodRunning {
			possibleCIDRs.Insert(fmt.Sprintf("%s/32", status.PodIP))
		}
	}
	for _, cidr := range currentCIDRs {
		if !possibleCIDRs.Has(cidr) {
			glog.V(2).Infof("Removing CIDR: %s (%v)", cidr, possibleCIDRs)
			if err := kl.shaper.Reset(cidr); err != nil {
				return err
			}
		}
	}
	return nil
}

// Compares the map of current volumes to the map of desired volumes.
// If an active volume does not have a respective desired volume, clean it up.
// This method is blocking:
// 1) it talks to API server to find volumes bound to persistent volume claims
// 2) it talks to cloud to detach volumes
func (kl *Kubelet) cleanupOrphanedVolumes(pods []*api.Pod, runningPods []*kubecontainer.Pod) error {
	desiredVolumes := kl.getDesiredVolumes(pods)
	currentVolumes := kl.getPodVolumesFromDisk()

	runningSet := sets.String{}
	for _, pod := range runningPods {
		runningSet.Insert(string(pod.ID))
	}

	for name, cleaner := range currentVolumes {
		if _, ok := desiredVolumes[name]; !ok {
			parts := strings.Split(name, "/")
			if runningSet.Has(parts[0]) {
				glog.Infof("volume %q, still has a container running (%q), skipping teardown", name, parts[0])
				continue
			}
			//TODO (jonesdl) We should somehow differentiate between volumes that are supposed
			//to be deleted and volumes that are leftover after a crash.
			glog.V(3).Infof("Orphaned volume %q found, tearing down volume", name)
			// TODO(yifan): Refactor this hacky string manipulation.
			kl.volumeManager.DeleteVolumes(types.UID(parts[0]))
			// Get path reference count
			volumePath := cleaner.Unmounter.GetPath()
			refs, err := mount.GetMountRefs(kl.mounter, volumePath)
			if err != nil {
				glog.Errorf("Could not get mount path references for %q: %v", volumePath, err)
			}
			//TODO (jonesdl) This should not block other kubelet synchronization procedures
			err = cleaner.Unmounter.TearDown()
			if err != nil {
				glog.Errorf("Could not tear down volume %q at %q: %v", name, volumePath, err)
			}

			// volume is unmounted.  some volumes also require detachment from the node.
			if cleaner.Detacher != nil && len(refs) == 1 {

				detacher := *cleaner.Detacher
				devicePath, _, err := mount.GetDeviceNameFromMount(kl.mounter, refs[0])
				if err != nil {
					glog.Errorf("Could not find device path %v", err)
				}

				if err = detacher.UnmountDevice(refs[0], kl.mounter); err != nil {
					glog.Errorf("Could not unmount the global mount for %q: %v", name, err)
				}

				pdName := path.Base(refs[0])
				err = detacher.Detach(pdName, kl.hostname)
				if err != nil {
					glog.Errorf("Could not detach volume %q at %q: %v", name, volumePath, err)
				}

				go func() {
					if err = detacher.WaitForDetach(devicePath, maxWaitForVolumeOps); err != nil {
						glog.Errorf("Error while waiting for detach: %v", err)
					}
				}()
			}
		}
	}
	return nil
}

// pastActiveDeadline returns true if the pod has been active for more than
// ActiveDeadlineSeconds.
func (kl *Kubelet) pastActiveDeadline(pod *api.Pod) bool {
	if pod.Spec.ActiveDeadlineSeconds != nil {
		podStatus, ok := kl.statusManager.GetPodStatus(pod.UID)
		if !ok {
			podStatus = pod.Status
		}
		if !podStatus.StartTime.IsZero() {
			startTime := podStatus.StartTime.Time
			duration := kl.clock.Since(startTime)
			allowedDuration := time.Duration(*pod.Spec.ActiveDeadlineSeconds) * time.Second
			if duration >= allowedDuration {
				return true
			}
		}
	}
	return false
}

// Get pods which should be resynchronized. Currently, the following pod should be resynchronized:
//   * pod whose work is ready.
//   * pod past the active deadline.
//   * internal modules that request sync of a pod.
func (kl *Kubelet) getPodsToSync() []*api.Pod {
	allPods := kl.podManager.GetPods()
	podUIDs := kl.workQueue.GetWork()
	podUIDSet := sets.NewString()
	for _, podUID := range podUIDs {
		podUIDSet.Insert(string(podUID))
	}
	var podsToSync []*api.Pod
	for _, pod := range allPods {
		// TODO: move active deadline code into a sync/evict pattern
		if kl.pastActiveDeadline(pod) {
			// The pod has passed the active deadline
			podsToSync = append(podsToSync, pod)
			continue
		}
		if podUIDSet.Has(string(pod.UID)) {
			// The work of the pod is ready
			podsToSync = append(podsToSync, pod)
			continue
		}
		for _, podSyncLoopHandler := range kl.PodSyncLoopHandlers {
			if podSyncLoopHandler.ShouldSync(pod) {
				podsToSync = append(podsToSync, pod)
				break
			}
		}
	}
	return podsToSync
}

// Returns true if pod is in the terminated state ("Failed" or "Succeeded").
func (kl *Kubelet) podIsTerminated(pod *api.Pod) bool {
	var status api.PodStatus
	// Check the cached pod status which was set after the last sync.
	status, ok := kl.statusManager.GetPodStatus(pod.UID)
	if !ok {
		// If there is no cached status, use the status from the
		// apiserver. This is useful if kubelet has recently been
		// restarted.
		status = pod.Status
	}
	if status.Phase == api.PodFailed || status.Phase == api.PodSucceeded {
		return true
	}

	return false
}

// filterOutTerminatedPods returns the given pods which the status manager
// does not consider failed or succeeded.
func (kl *Kubelet) filterOutTerminatedPods(pods []*api.Pod) []*api.Pod {
	var filteredPods []*api.Pod
	for _, p := range pods {
		if kl.podIsTerminated(p) {
			continue
		}
		filteredPods = append(filteredPods, p)
	}
	return filteredPods
}

// removeOrphanedPodStatuses removes obsolete entries in podStatus where
// the pod is no longer considered bound to this node.
func (kl *Kubelet) removeOrphanedPodStatuses(pods []*api.Pod, mirrorPods []*api.Pod) {
	podUIDs := make(map[types.UID]bool)
	for _, pod := range pods {
		podUIDs[pod.UID] = true
	}
	for _, pod := range mirrorPods {
		podUIDs[pod.UID] = true
	}
	kl.statusManager.RemoveOrphanedStatuses(podUIDs)
}

// deletePod deletes the pod from the internal state of the kubelet by:
// 1.  stopping the associated pod worker asynchronously
// 2.  signaling to kill the pod by sending on the podKillingCh channel
//
// deletePod returns an error if not all sources are ready or the pod is not
// found in the runtime cache.
func (kl *Kubelet) deletePod(pod *api.Pod) error {
	if pod == nil {
		return fmt.Errorf("deletePod does not allow nil pod")
	}
	if !kl.sourcesReady.AllReady() {
		// If the sources aren't ready, skip deletion, as we may accidentally delete pods
		// for sources that haven't reported yet.
		return fmt.Errorf("skipping delete because sources aren't ready yet")
	}
	kl.podWorkers.ForgetWorker(pod.UID)

	// Runtime cache may not have been updated to with the pod, but it's okay
	// because the periodic cleanup routine will attempt to delete again later.
	runningPods, err := kl.runtimeCache.GetPods()
	if err != nil {
		return fmt.Errorf("error listing containers: %v", err)
	}
	runningPod := kubecontainer.Pods(runningPods).FindPod("", pod.UID)
	if runningPod.IsEmpty() {
		return fmt.Errorf("pod not found")
	}
	podPair := kubecontainer.PodPair{APIPod: pod, RunningPod: &runningPod}

	kl.podKillingCh <- &podPair
	// TODO: delete the mirror pod here?

	// We leave the volume/directory cleanup to the periodic cleanup routine.
	return nil
}

// empty is a placeholder type used to implement a set
type empty struct{}

// HandlePodCleanups performs a series of cleanup work, including terminating
// pod workers, killing unwanted pods, and removing orphaned volumes/pod
// directories.
// TODO(yujuhong): This function is executed by the main sync loop, so it
// should not contain any blocking calls. Re-examine the function and decide
// whether or not we should move it into a separte goroutine.
func (kl *Kubelet) HandlePodCleanups() error {
	allPods, mirrorPods := kl.podManager.GetPodsAndMirrorPods()
	// Pod phase progresses monotonically. Once a pod has reached a final state,
	// it should never leave regardless of the restart policy. The statuses
	// of such pods should not be changed, and there is no need to sync them.
	// TODO: the logic here does not handle two cases:
	//   1. If the containers were removed immediately after they died, kubelet
	//      may fail to generate correct statuses, let alone filtering correctly.
	//   2. If kubelet restarted before writing the terminated status for a pod
	//      to the apiserver, it could still restart the terminated pod (even
	//      though the pod was not considered terminated by the apiserver).
	// These two conditions could be alleviated by checkpointing kubelet.
	activePods := kl.filterOutTerminatedPods(allPods)

	desiredPods := make(map[types.UID]empty)
	for _, pod := range activePods {
		desiredPods[pod.UID] = empty{}
	}
	// Stop the workers for no-longer existing pods.
	// TODO: is here the best place to forget pod workers?
	kl.podWorkers.ForgetNonExistingPodWorkers(desiredPods)
	kl.probeManager.CleanupPods(activePods)

	runningPods, err := kl.runtimeCache.GetPods()
	if err != nil {
		glog.Errorf("Error listing containers: %#v", err)
		return err
	}
	for _, pod := range runningPods {
		if _, found := desiredPods[pod.ID]; !found {
			kl.podKillingCh <- &kubecontainer.PodPair{APIPod: nil, RunningPod: pod}
		}
	}

	kl.removeOrphanedPodStatuses(allPods, mirrorPods)
	// Note that we just killed the unwanted pods. This may not have reflected
	// in the cache. We need to bypass the cache to get the latest set of
	// running pods to clean up the volumes.
	// TODO: Evaluate the performance impact of bypassing the runtime cache.
	runningPods, err = kl.containerRuntime.GetPods(false)
	if err != nil {
		glog.Errorf("Error listing containers: %#v", err)
		return err
	}

	// Remove any orphaned volumes.
	// Note that we pass all pods (including terminated pods) to the function,
	// so that we don't remove volumes associated with terminated but not yet
	// deleted pods.
	err = kl.cleanupOrphanedVolumes(allPods, runningPods)
	if err != nil {
		glog.Errorf("Failed cleaning up orphaned volumes: %v", err)
		return err
	}

	// Remove any orphaned pod directories.
	// Note that we pass all pods (including terminated pods) to the function,
	// so that we don't remove directories associated with terminated but not yet
	// deleted pods.
	err = kl.cleanupOrphanedPodDirs(allPods, runningPods)
	if err != nil {
		glog.Errorf("Failed cleaning up orphaned pod directories: %v", err)
		return err
	}

	// Remove any orphaned mirror pods.
	kl.podManager.DeleteOrphanedMirrorPods()

	// Clear out any old bandwidth rules
	if err = kl.cleanupBandwidthLimits(allPods); err != nil {
		return err
	}

	kl.backOff.GC()
	return err
}

// 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()
	resultCh := make(chan types.UID)
	defer close(resultCh)
	for {
		select {
		case podPair, ok := <-kl.podKillingCh:
			runningPod := podPair.RunningPod
			apiPod := podPair.APIPod
			if !ok {
				return
			}
			if killing.Has(string(runningPod.ID)) {
				// The pod is already being killed.
				break
			}
			killing.Insert(string(runningPod.ID))
			go func(apiPod *api.Pod, runningPod *kubecontainer.Pod, ch chan types.UID) {
				defer func() {
					ch <- runningPod.ID
				}()
				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)
				}
			}(apiPod, runningPod, resultCh)

		case podID := <-resultCh:
			killing.Delete(string(podID))
		}
	}
}

// podsByCreationTime makes an array of pods sortable by their creation
// timestamps.
// TODO: move into util package
type podsByCreationTime []*api.Pod

func (s podsByCreationTime) Len() int {
	return len(s)
}

func (s podsByCreationTime) Swap(i, j int) {
	s[i], s[j] = s[j], s[i]
}

func (s podsByCreationTime) Less(i, j int) bool {
	return s[i].CreationTimestamp.Before(s[j].CreationTimestamp)
}

// checkHostPortConflicts detects pods with conflicted host ports.
func hasHostPortConflicts(pods []*api.Pod) bool {
	ports := sets.String{}
	for _, pod := range pods {
		if errs := validation.AccumulateUniqueHostPorts(pod.Spec.Containers, &ports, field.NewPath("spec", "containers")); len(errs) > 0 {
			glog.Errorf("Pod %q: HostPort is already allocated, ignoring: %v", format.Pod(pod), errs)
			return true
		}
	}
	return false
}

// handleOutOfDisk detects if pods can't fit due to lack of disk space.
func (kl *Kubelet) isOutOfDisk() bool {
	outOfDockerDisk := false
	outOfRootDisk := false
	// Check disk space once globally and reject or accept all new pods.
	withinBounds, err := kl.diskSpaceManager.IsDockerDiskSpaceAvailable()
	// Assume enough space in case of errors.
	if err == nil && !withinBounds {
		outOfDockerDisk = true
	}

	withinBounds, err = kl.diskSpaceManager.IsRootDiskSpaceAvailable()
	// Assume enough space in case of errors.
	if err == nil && !withinBounds {
		outOfRootDisk = true
	}
	return outOfDockerDisk || outOfRootDisk
}

// matchesNodeSelector returns true if pod matches node's labels.
func (kl *Kubelet) matchesNodeSelector(pod *api.Pod) bool {
	if kl.standaloneMode {
		return true
	}
	node, err := kl.GetNode()
	if err != nil {
		glog.Errorf("error getting node: %v", err)
		return true
	}
	return predicates.PodMatchesNodeLabels(pod, node)
}

// rejectPod records an event about the pod with the given reason and message,
// and updates the pod to the failed phase in the status manage.
func (kl *Kubelet) rejectPod(pod *api.Pod, reason, message string) {
	kl.recorder.Eventf(pod, api.EventTypeWarning, reason, message)
	kl.statusManager.SetPodStatus(pod, api.PodStatus{
		Phase:   api.PodFailed,
		Reason:  reason,
		Message: "Pod " + message})
}

// canAdmitPod determines if a pod can be admitted, and gives a reason if it
// cannot. "pod" is new pod, while "pods" include all admitted pods plus the
// new pod. The function returns a boolean value indicating whether the pod
// can be admitted, a brief single-word reason and a message explaining why
// the pod cannot be admitted.
func (kl *Kubelet) canAdmitPod(pods []*api.Pod, pod *api.Pod) (bool, string, string) {
	node, err := kl.getNodeAnyWay()
	if err != nil {
		glog.Errorf("Cannot get Node info: %v", err)
		return false, "InvalidNodeInfo", "Kubelet cannot get node info."
	}
	otherPods := []*api.Pod{}
	for _, p := range pods {
		if p != pod {
			otherPods = append(otherPods, p)
		}
	}

	// the kubelet will invoke each pod admit handler in sequence
	// if any handler rejects, the pod is rejected.
	// TODO: move predicate check into a pod admitter
	// TODO: move out of disk check into a pod admitter
	// TODO: out of resource eviction should have a pod admitter call-out
	attrs := &lifecycle.PodAdmitAttributes{Pod: pod, OtherPods: otherPods}
	for _, podAdmitHandler := range kl.PodAdmitHandlers {
		if result := podAdmitHandler.Admit(attrs); !result.Admit {
			return false, result.Reason, result.Message
		}
	}
	nodeInfo := schedulercache.NewNodeInfo(otherPods...)
	nodeInfo.SetNode(node)
	fit, err := predicates.GeneralPredicates(pod, nodeInfo)
	if !fit {
		if re, ok := err.(*predicates.PredicateFailureError); ok {
			reason := re.PredicateName
			message := re.Error()
			glog.V(2).Infof("Predicate failed on Pod: %v, for reason: %v", format.Pod(pod), message)
			return fit, reason, message
		}
		if re, ok := err.(*predicates.InsufficientResourceError); ok {
			reason := fmt.Sprintf("OutOf%s", re.ResourceName)
			message := re.Error()
			glog.V(2).Infof("Predicate failed on Pod: %v, for reason: %v", format.Pod(pod), message)
			return fit, reason, message
		}
		reason := "UnexpectedPredicateFailureType"
		message := fmt.Sprintf("GeneralPredicates failed due to %v, which is unexpected.", err)
		glog.Warningf("Failed to admit pod %v - %s", format.Pod(pod), message)
		return fit, reason, message
	}
	// TODO: When disk space scheduling is implemented (#11976), remove the out-of-disk check here and
	// add the disk space predicate to predicates.GeneralPredicates.
	if kl.isOutOfDisk() {
		glog.Warningf("Failed to admit pod %v - %s", format.Pod(pod), "predicate fails due to isOutOfDisk")
		return false, "OutOfDisk", "cannot be started due to lack of disk space."
	}

	return true, "", ""
}

// 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)
	housekeepingTicker := time.NewTicker(housekeepingPeriod)
	plegCh := kl.pleg.Watch()
	for {
		if rs := kl.runtimeState.errors(); len(rs) != 0 {
			glog.Infof("skipping pod synchronization - %v", rs)
			time.Sleep(5 * time.Second)
			continue
		}
		if !kl.syncLoopIteration(updates, handler, syncTicker.C, housekeepingTicker.C, plegCh) {
			break
		}
	}
}

// syncLoopIteration reads from various channels and dispatches pods to the
// given handler.
//
// Arguments:
// 1.  configCh:       a channel to read config events from
// 2.  handler:        the SyncHandler to dispatch pods to
// 3.  syncCh:         a channel to read periodic sync events from
// 4.  houseKeepingCh: a channel to read housekeeping events from
// 5.  plegCh:         a channel to read PLEG updates from
//
// Events are also read from the kubelet liveness manager's update channel.
//
// The workflow is to read from one of the channels, handle that event, and
// update the timestamp in the sync loop monitor.
//
// Here is an appropriate place to note that despite the syntactical
// similarity to the switch statement, the case statements in a select are
// evaluated in a pseudorandom order if there are multiple channels ready to
// read from when the select is evaluated.  In other words, case statements
// are evaluated in random order, and you can not assume that the case
// statements evaluate in order if multiple channels have events.
//
// With that in mind, in truly no particular order, the different channels
// are handled as follows:
//
// * configCh: dispatch the pods for the config change to the appropriate
//             handler callback for the event type
// * plegCh: update the runtime cache; sync pod
// * syncCh: sync all pods waiting for sync
// * houseKeepingCh: trigger cleanup of pods
// * liveness manager: sync pods that have failed or in which one or more
//                     containers have failed liveness checks
func (kl *Kubelet) syncLoopIteration(configCh <-chan kubetypes.PodUpdate, handler SyncHandler,
	syncCh <-chan time.Time, housekeepingCh <-chan time.Time, plegCh <-chan *pleg.PodLifecycleEvent) bool {
	kl.syncLoopMonitor.Store(kl.clock.Now())
	select {
	case u, open := <-configCh:
		// Update from a config source; dispatch it to the right handler
		// callback.
		if !open {
			glog.Errorf("Update channel is closed. Exiting the sync loop.")
			return false
		}
		kl.sourcesReady.AddSource(u.Source)

		switch u.Op {
		case kubetypes.ADD:
			glog.V(2).Infof("SyncLoop (ADD, %q): %q", u.Source, format.Pods(u.Pods))
			// After restarting, kubelet will get all existing pods through
			// ADD as if they are new pods. These pods will then go through the
			// admission process and *may* be rejcted. This can be resolved
			// once we have checkpointing.
			handler.HandlePodAdditions(u.Pods)
		case kubetypes.UPDATE:
			glog.V(2).Infof("SyncLoop (UPDATE, %q): %q", u.Source, format.Pods(u.Pods))
			handler.HandlePodUpdates(u.Pods)
		case kubetypes.REMOVE:
			glog.V(2).Infof("SyncLoop (REMOVE, %q): %q", u.Source, format.Pods(u.Pods))
			handler.HandlePodDeletions(u.Pods)
		case kubetypes.RECONCILE:
			glog.V(4).Infof("SyncLoop (RECONCILE, %q): %q", u.Source, format.Pods(u.Pods))
			handler.HandlePodReconcile(u.Pods)
		case kubetypes.SET:
			// TODO: Do we want to support this?
			glog.Errorf("Kubelet does not support snapshot update")
		}
	case e := <-plegCh:
		// PLEG event for a pod; sync it.
		pod, ok := kl.podManager.GetPodByUID(e.ID)
		if !ok {
			// If the pod no longer exists, ignore the event.
			glog.V(4).Infof("SyncLoop (PLEG): ignore irrelevant event: %#v", e)
			break
		}
		glog.V(2).Infof("SyncLoop (PLEG): %q, event: %#v", format.Pod(pod), e)
		handler.HandlePodSyncs([]*api.Pod{pod})
	case <-syncCh:
		// Sync pods waiting for sync
		podsToSync := kl.getPodsToSync()
		if len(podsToSync) == 0 {
			break
		}
		glog.V(4).Infof("SyncLoop (SYNC): %d pods; %s", len(podsToSync), format.Pods(podsToSync))
		kl.HandlePodSyncs(podsToSync)
	case update := <-kl.livenessManager.Updates():
		if update.Result == proberesults.Failure {
			// The liveness manager detected a failure; sync the pod.

			// We should not use the pod from livenessManager, because it is never updated after
			// initialization.
			pod, ok := kl.podManager.GetPodByUID(update.PodUID)
			if !ok {
				// If the pod no longer exists, ignore the update.
				glog.V(4).Infof("SyncLoop (container unhealthy): ignore irrelevant update: %#v", update)
				break
			}
			glog.V(1).Infof("SyncLoop (container unhealthy): %q", format.Pod(pod))
			handler.HandlePodSyncs([]*api.Pod{pod})
		}
	case <-housekeepingCh:
		if !kl.sourcesReady.AllReady() {
			// If the sources aren't ready, skip housekeeping, as we may
			// accidentally delete pods from unready sources.
			glog.V(4).Infof("SyncLoop (housekeeping, skipped): sources aren't ready yet.")
		} else {
			glog.V(4).Infof("SyncLoop (housekeeping)")
			if err := handler.HandlePodCleanups(); err != nil {
				glog.Errorf("Failed cleaning pods: %v", err)
			}
		}
	}
	kl.syncLoopMonitor.Store(kl.clock.Now())
	return true
}

// dispatchWork starts the asynchronous sync of the pod in a pod worker.
// If the pod is terminated, dispatchWork
func (kl *Kubelet) dispatchWork(pod *api.Pod, syncType kubetypes.SyncPodType, mirrorPod *api.Pod, start time.Time) {
	if kl.podIsTerminated(pod) {
		if pod.DeletionTimestamp != nil {
			// If the pod is in a terminated state, there is no pod worker to
			// handle the work item. Check if the DeletionTimestamp has been
			// set, and force a status update to trigger a pod deletion request
			// to the apiserver.
			kl.statusManager.TerminatePod(pod)
		}
		return
	}
	// Run the sync in an async worker.
	kl.podWorkers.UpdatePod(&UpdatePodOptions{
		Pod:        pod,
		MirrorPod:  mirrorPod,
		UpdateType: syncType,
		OnCompleteFunc: func(err error) {
			if err != nil {
				metrics.PodWorkerLatency.WithLabelValues(syncType.String()).Observe(metrics.SinceInMicroseconds(start))
			}
		},
	})
	// Note the number of containers for new pods.
	if syncType == kubetypes.SyncPodCreate {
		metrics.ContainersPerPodCount.Observe(float64(len(pod.Spec.Containers)))
	}
}

// TODO: Consider handling all mirror pods updates in a separate component.
func (kl *Kubelet) handleMirrorPod(mirrorPod *api.Pod, start time.Time) {
	// Mirror pod ADD/UPDATE/DELETE operations are considered an UPDATE to the
	// corresponding static pod. Send update to the pod worker if the static
	// pod exists.
	if pod, ok := kl.podManager.GetPodByMirrorPod(mirrorPod); ok {
		kl.dispatchWork(pod, kubetypes.SyncPodUpdate, mirrorPod, start)
	}
}

// HandlePodAdditions is the callback in SyncHandler for pods being added from
// a config source.
func (kl *Kubelet) HandlePodAdditions(pods []*api.Pod) {
	start := kl.clock.Now()
	sort.Sort(podsByCreationTime(pods))
	for _, pod := range pods {
		kl.podManager.AddPod(pod)
		if kubepod.IsMirrorPod(pod) {
			kl.handleMirrorPod(pod, start)
			continue
		}
		// Note that allPods includes the new pod since we added at the
		// beginning of the loop.
		allPods := kl.podManager.GetPods()
		// We failed pods that we rejected, so activePods include all admitted
		// pods that are alive and the new pod.
		activePods := kl.filterOutTerminatedPods(allPods)
		// Check if we can admit the pod; if not, reject it.
		if ok, reason, message := kl.canAdmitPod(activePods, pod); !ok {
			kl.rejectPod(pod, reason, message)
			continue
		}
		mirrorPod, _ := kl.podManager.GetMirrorPodByPod(pod)
		kl.dispatchWork(pod, kubetypes.SyncPodCreate, mirrorPod, start)
		kl.probeManager.AddPod(pod)
	}
}

// HandlePodUpdates is the callback in the SyncHandler interface for pods
// being updated from a config source.
func (kl *Kubelet) HandlePodUpdates(pods []*api.Pod) {
	start := kl.clock.Now()
	for _, pod := range pods {
		kl.podManager.UpdatePod(pod)
		if kubepod.IsMirrorPod(pod) {
			kl.handleMirrorPod(pod, start)
			continue
		}
		// TODO: Evaluate if we need to validate and reject updates.

		mirrorPod, _ := kl.podManager.GetMirrorPodByPod(pod)
		kl.dispatchWork(pod, kubetypes.SyncPodUpdate, mirrorPod, start)
	}
}

// HandlePodDeletions is the callback in the SyncHandler interface for pods
// being deleted from a config source.
func (kl *Kubelet) HandlePodDeletions(pods []*api.Pod) {
	start := kl.clock.Now()
	for _, pod := range pods {
		kl.podManager.DeletePod(pod)
		if kubepod.IsMirrorPod(pod) {
			kl.handleMirrorPod(pod, start)
			continue
		}
		// Deletion is allowed to fail because the periodic cleanup routine
		// will trigger deletion again.
		if err := kl.deletePod(pod); err != nil {
			glog.V(2).Infof("Failed to delete pod %q, err: %v", format.Pod(pod), err)
		}
		kl.probeManager.RemovePod(pod)
	}
}

// HandlePodReconcile is the callback in the SyncHandler interface for pods
// that should be reconciled.
func (kl *Kubelet) HandlePodReconcile(pods []*api.Pod) {
	for _, pod := range pods {
		// Update the pod in pod manager, status manager will do periodically reconcile according
		// to the pod manager.
		kl.podManager.UpdatePod(pod)
	}
}

// HandlePodSyncs is the callback in the syncHandler interface for pods
// that should be dispatched to pod workers for sync.
func (kl *Kubelet) HandlePodSyncs(pods []*api.Pod) {
	start := kl.clock.Now()
	for _, pod := range pods {
		mirrorPod, _ := kl.podManager.GetMirrorPodByPod(pod)
		kl.dispatchWork(pod, kubetypes.SyncPodSync, mirrorPod, start)
	}
}

// LatestLoopEntryTime returns the last time in the sync loop monitor.
func (kl *Kubelet) LatestLoopEntryTime() time.Time {
	val := kl.syncLoopMonitor.Load()
	if val == nil {
		return time.Time{}
	}
	return val.(time.Time)
}

// PLEGHealthCheck returns whether the PLEG is healty.
func (kl *Kubelet) PLEGHealthCheck() (bool, error) {
	return kl.pleg.Healthy()
}

// validateContainerLogStatus returns the container ID for the desired container to retrieve logs for, based on the state
// of the container. The previous flag will only return the logs for the the last terminated container, otherwise, the current
// running container is preferred over a previous termination. If info about the container is not available then a specific
// error is returned to the end user.
func (kl *Kubelet) validateContainerLogStatus(podName string, podStatus *api.PodStatus, containerName string, previous bool) (containerID kubecontainer.ContainerID, err error) {
	var cID string

	cStatus, found := api.GetContainerStatus(podStatus.ContainerStatuses, containerName)
	if !found {
		return kubecontainer.ContainerID{}, fmt.Errorf("container %q in pod %q is not available", containerName, podName)
	}
	lastState := cStatus.LastTerminationState
	waiting, running, terminated := cStatus.State.Waiting, cStatus.State.Running, cStatus.State.Terminated

	switch {
	case previous:
		if lastState.Terminated == nil {
			return kubecontainer.ContainerID{}, fmt.Errorf("previous terminated container %q in pod %q not found", containerName, podName)
		}
		cID = lastState.Terminated.ContainerID

	case running != nil:
		cID = cStatus.ContainerID

	case terminated != nil:
		cID = terminated.ContainerID

	case lastState.Terminated != nil:
		cID = lastState.Terminated.ContainerID

	case waiting != nil:
		// output some info for the most common pending failures
		switch reason := waiting.Reason; reason {
		case kubecontainer.ErrImagePull.Error():
			return kubecontainer.ContainerID{}, fmt.Errorf("container %q in pod %q is waiting to start: image can't be pulled", containerName, podName)
		case kubecontainer.ErrImagePullBackOff.Error():
			return kubecontainer.ContainerID{}, fmt.Errorf("container %q in pod %q is waiting to start: trying and failing to pull image", containerName, podName)
		default:
			return kubecontainer.ContainerID{}, fmt.Errorf("container %q in pod %q is waiting to start: %v", containerName, podName, reason)
		}
	default:
		// unrecognized state
		return kubecontainer.ContainerID{}, fmt.Errorf("container %q in pod %q is waiting to start - no logs yet", containerName, podName)
	}

	return kubecontainer.ParseContainerID(cID), nil
}

// GetKubeletContainerLogs returns logs from the container
// TODO: this method is returning logs of random container attempts, when it should be returning the most recent attempt
// or all of them.
func (kl *Kubelet) GetKubeletContainerLogs(podFullName, containerName string, logOptions *api.PodLogOptions, stdout, stderr io.Writer) error {
	// TODO(vmarmol): Refactor to not need the pod status and verification.
	// Pod workers periodically write status to statusManager. If status is not
	// cached there, something is wrong (or kubelet just restarted and hasn't
	// caught up yet). Just assume the pod is not ready yet.
	name, namespace, err := kubecontainer.ParsePodFullName(podFullName)
	if err != nil {
		return fmt.Errorf("unable to parse pod full name %q: %v", podFullName, err)
	}

	pod, ok := kl.GetPodByName(namespace, name)
	if !ok {
		return fmt.Errorf("pod %q cannot be found - no logs available", name)
	}

	podUID := pod.UID
	if mirrorPod, ok := kl.podManager.GetMirrorPodByPod(pod); ok {
		podUID = mirrorPod.UID
	}
	podStatus, found := kl.statusManager.GetPodStatus(podUID)
	if !found {
		// If there is no cached status, use the status from the
		// apiserver. This is useful if kubelet has recently been
		// restarted.
		podStatus = pod.Status
	}

	containerID, err := kl.validateContainerLogStatus(pod.Name, &podStatus, containerName, logOptions.Previous)
	if err != nil {
		return err
	}
	return kl.containerRuntime.GetContainerLogs(pod, containerID, logOptions, stdout, stderr)
}

// updateRuntimeUp calls the container runtime status callback, initializing
// the runtime dependent modules when the container runtime first comes up,
// and returns an error if the status check fails.  If the status check is OK,
// update the container runtime uptime in the kubelet runtimeState.
func (kl *Kubelet) updateRuntimeUp() {
	if err := kl.containerRuntime.Status(); err != nil {
		glog.Errorf("Container runtime sanity check failed: %v", err)
		return
	}
	kl.oneTimeInitializer.Do(kl.initializeRuntimeDependentModules)
	kl.runtimeState.setRuntimeSync(kl.clock.Now())
}

// TODO: remove when kubenet plugin is ready
// NOTE!!! if you make changes here, also make them to kubenet
func (kl *Kubelet) reconcileCBR0(podCIDR string) error {
	if podCIDR == "" {
		glog.V(5).Info("PodCIDR not set. Will not configure cbr0.")
		return nil
	}
	glog.V(5).Infof("PodCIDR is set to %q", podCIDR)
	_, cidr, err := net.ParseCIDR(podCIDR)
	if err != nil {
		return err
	}
	// Set cbr0 interface address to first address in IPNet
	cidr.IP.To4()[3] += 1
	if err := ensureCbr0(cidr, kl.hairpinMode == componentconfig.PromiscuousBridge, kl.babysitDaemons); err != nil {
		return err
	}
	if kl.shapingEnabled() {
		if kl.shaper == nil {
			glog.V(5).Info("Shaper is nil, creating")
			kl.shaper = bandwidth.NewTCShaper("cbr0")
		}
		return kl.shaper.ReconcileInterface()
	}
	return nil
}

// updateNodeStatus updates node status to master with retries.
func (kl *Kubelet) updateNodeStatus() error {
	for i := 0; i < nodeStatusUpdateRetry; i++ {
		if err := kl.tryUpdateNodeStatus(); err != nil {
			glog.Errorf("Error updating node status, will retry: %v", err)
		} else {
			return nil
		}
	}
	return fmt.Errorf("update node status exceeds retry count")
}

// recordNodeStatusEvent records an event of the given type with the given
// message for the node.
func (kl *Kubelet) recordNodeStatusEvent(eventtype, event string) {
	glog.V(2).Infof("Recording %s event message for node %s", event, kl.nodeName)
	// TODO: This requires a transaction, either both node status is updated
	// and event is recorded or neither should happen, see issue #6055.
	kl.recorder.Eventf(kl.nodeRef, eventtype, event, "Node %s status is now: %s", kl.nodeName, event)
}

// syncNetworkStatus updates the network state, ensuring that the network is
// configured correctly if the kubelet is set to configure cbr0:
// * handshake flannel helper if the flannel experimental overlay is being used.
// * ensure that iptables masq rules are setup
// * reconcile cbr0 with the pod CIDR
func (kl *Kubelet) syncNetworkStatus() {
	var err error
	if kl.configureCBR0 {
		if kl.flannelExperimentalOverlay {
			podCIDR, err := kl.flannelHelper.Handshake()
			if err != nil {
				glog.Infof("Flannel server handshake failed %v", err)
				return
			}
			kl.updatePodCIDR(podCIDR)
		}
		if err := ensureIPTablesMasqRule(kl.nonMasqueradeCIDR); err != nil {
			err = fmt.Errorf("Error on adding ip table rules: %v", err)
			glog.Error(err)
			kl.runtimeState.setNetworkState(err)
			return
		}
		podCIDR := kl.runtimeState.podCIDR()
		if len(podCIDR) == 0 {
			err = fmt.Errorf("ConfigureCBR0 requested, but PodCIDR not set. Will not configure CBR0 right now")
			glog.Warning(err)
		} else if err = kl.reconcileCBR0(podCIDR); err != nil {
			err = fmt.Errorf("Error configuring cbr0: %v", err)
			glog.Error(err)
		}
		if err != nil {
			kl.runtimeState.setNetworkState(err)
			return
		}
	}

	kl.runtimeState.setNetworkState(kl.networkPlugin.Status())
}

// Set addresses for the node.
func (kl *Kubelet) setNodeAddress(node *api.Node) error {
	// Set addresses for the node.
	if kl.cloud != nil {
		instances, ok := kl.cloud.Instances()
		if !ok {
			return fmt.Errorf("failed to get instances from cloud provider")
		}
		// TODO(roberthbailey): Can we do this without having credentials to talk
		// to the cloud provider?
		// TODO(justinsb): We can if CurrentNodeName() was actually CurrentNode() and returned an interface
		nodeAddresses, err := instances.NodeAddresses(kl.nodeName)
		if err != nil {
			return fmt.Errorf("failed to get node address from cloud provider: %v", err)
		}
		node.Status.Addresses = nodeAddresses
	} else {
		if kl.nodeIP != nil {
			node.Status.Addresses = []api.NodeAddress{
				{Type: api.NodeLegacyHostIP, Address: kl.nodeIP.String()},
				{Type: api.NodeInternalIP, Address: kl.nodeIP.String()},
			}
		} else if addr := net.ParseIP(kl.hostname); addr != nil {
			node.Status.Addresses = []api.NodeAddress{
				{Type: api.NodeLegacyHostIP, Address: addr.String()},
				{Type: api.NodeInternalIP, Address: addr.String()},
			}
		} else {
			addrs, err := net.LookupIP(node.Name)
			if err != nil {
				return fmt.Errorf("can't get ip address of node %s: %v", node.Name, err)
			} else if len(addrs) == 0 {
				return fmt.Errorf("no ip address for node %v", node.Name)
			} else {
				// check all ip addresses for this node.Name and try to find the first non-loopback IPv4 address.
				// If no match is found, it uses the IP of the interface with gateway on it.
				for _, ip := range addrs {
					if ip.IsLoopback() {
						continue
					}

					if ip.To4() != nil {
						node.Status.Addresses = []api.NodeAddress{
							{Type: api.NodeLegacyHostIP, Address: ip.String()},
							{Type: api.NodeInternalIP, Address: ip.String()},
						}
						break
					}
				}

				if len(node.Status.Addresses) == 0 {
					ip, err := utilnet.ChooseHostInterface()
					if err != nil {
						return err
					}

					node.Status.Addresses = []api.NodeAddress{
						{Type: api.NodeLegacyHostIP, Address: ip.String()},
						{Type: api.NodeInternalIP, Address: ip.String()},
					}
				}
			}
		}
	}
	return nil
}

func (kl *Kubelet) setNodeStatusMachineInfo(node *api.Node) {
	// TODO: Post NotReady if we cannot get MachineInfo from cAdvisor. This needs to start
	// cAdvisor locally, e.g. for test-cmd.sh, and in integration test.
	info, err := kl.GetCachedMachineInfo()
	if err != nil {
		// TODO(roberthbailey): This is required for test-cmd.sh to pass.
		// See if the test should be updated instead.
		node.Status.Capacity = api.ResourceList{
			api.ResourceCPU:       *resource.NewMilliQuantity(0, resource.DecimalSI),
			api.ResourceMemory:    resource.MustParse("0Gi"),
			api.ResourcePods:      *resource.NewQuantity(int64(kl.maxPods), resource.DecimalSI),
			api.ResourceNvidiaGPU: *resource.NewQuantity(int64(kl.nvidiaGPUs), resource.DecimalSI),
		}
		glog.Errorf("Error getting machine info: %v", err)
	} else {
		node.Status.NodeInfo.MachineID = info.MachineID
		node.Status.NodeInfo.SystemUUID = info.SystemUUID
		node.Status.Capacity = cadvisor.CapacityFromMachineInfo(info)
		node.Status.Capacity[api.ResourcePods] = *resource.NewQuantity(
			int64(kl.maxPods), resource.DecimalSI)
		node.Status.Capacity[api.ResourceNvidiaGPU] = *resource.NewQuantity(
			int64(kl.nvidiaGPUs), resource.DecimalSI)
		if node.Status.NodeInfo.BootID != "" &&
			node.Status.NodeInfo.BootID != info.BootID {
			// TODO: This requires a transaction, either both node status is updated
			// and event is recorded or neither should happen, see issue #6055.
			kl.recorder.Eventf(kl.nodeRef, api.EventTypeWarning, kubecontainer.NodeRebooted,
				"Node %s has been rebooted, boot id: %s", kl.nodeName, info.BootID)
		}
		node.Status.NodeInfo.BootID = info.BootID
	}

	// Set Allocatable.
	node.Status.Allocatable = make(api.ResourceList)
	for k, v := range node.Status.Capacity {
		value := *(v.Copy())
		if kl.reservation.System != nil {
			value.Sub(kl.reservation.System[k])
		}
		if kl.reservation.Kubernetes != nil {
			value.Sub(kl.reservation.Kubernetes[k])
		}
		if value.Amount != nil && value.Amount.Sign() < 0 {
			// Negative Allocatable resources don't make sense.
			value.Set(0)
		}
		node.Status.Allocatable[k] = value
	}
}

// Set versioninfo for the node.
func (kl *Kubelet) setNodeStatusVersionInfo(node *api.Node) {
	verinfo, err := kl.cadvisor.VersionInfo()
	if err != nil {
		glog.Errorf("Error getting version info: %v", err)
	} else {
		node.Status.NodeInfo.KernelVersion = verinfo.KernelVersion
		node.Status.NodeInfo.OSImage = verinfo.ContainerOsVersion

		runtimeVersion := "Unknown"
		if runtimeVer, err := kl.containerRuntime.Version(); err == nil {
			runtimeVersion = runtimeVer.String()
		}
		node.Status.NodeInfo.ContainerRuntimeVersion = fmt.Sprintf("%s://%s", kl.containerRuntime.Type(), runtimeVersion)

		node.Status.NodeInfo.KubeletVersion = version.Get().String()
		// TODO: kube-proxy might be different version from kubelet in the future
		node.Status.NodeInfo.KubeProxyVersion = version.Get().String()
	}

}

// Set daemonEndpoints for the node.
func (kl *Kubelet) setNodeStatusDaemonEndpoints(node *api.Node) {
	node.Status.DaemonEndpoints = *kl.daemonEndpoints
}

// Set images list for the node
func (kl *Kubelet) setNodeStatusImages(node *api.Node) {
	// Update image list of this node
	var imagesOnNode []api.ContainerImage
	containerImages, err := kl.imageManager.GetImageList()
	if err != nil {
		glog.Errorf("Error getting image list: %v", err)
	} else {
		for _, image := range containerImages {
			imagesOnNode = append(imagesOnNode, api.ContainerImage{
				Names:     append(image.RepoTags, image.RepoDigests...),
				SizeBytes: image.Size,
			})
		}
	}
	node.Status.Images = imagesOnNode
}

// Set the GOOS and GOARCH for this node
func (kl *Kubelet) setNodeStatusGoRuntime(node *api.Node) {
	node.Status.NodeInfo.OperatingSystem = goRuntime.GOOS
	node.Status.NodeInfo.Architecture = goRuntime.GOARCH
}

// Set status for the node.
func (kl *Kubelet) setNodeStatusInfo(node *api.Node) {
	kl.setNodeStatusMachineInfo(node)
	kl.setNodeStatusVersionInfo(node)
	kl.setNodeStatusDaemonEndpoints(node)
	kl.setNodeStatusImages(node)
	kl.setNodeStatusGoRuntime(node)
}

// Set Readycondition for the node.
func (kl *Kubelet) setNodeReadyCondition(node *api.Node) {
	// NOTE(aaronlevy): NodeReady condition needs to be the last in the list of node conditions.
	// This is due to an issue with version skewed kubelet and master components.
	// ref: https://github.com/kubernetes/kubernetes/issues/16961
	currentTime := unversioned.NewTime(kl.clock.Now())
	var newNodeReadyCondition api.NodeCondition
	if rs := kl.runtimeState.errors(); len(rs) == 0 {
		newNodeReadyCondition = api.NodeCondition{
			Type:              api.NodeReady,
			Status:            api.ConditionTrue,
			Reason:            "KubeletReady",
			Message:           "kubelet is posting ready status",
			LastHeartbeatTime: currentTime,
		}
	} else {
		newNodeReadyCondition = api.NodeCondition{
			Type:              api.NodeReady,
			Status:            api.ConditionFalse,
			Reason:            "KubeletNotReady",
			Message:           strings.Join(rs, ","),
			LastHeartbeatTime: currentTime,
		}
	}

	// Record any soft requirements that were not met in the container manager.
	status := kl.containerManager.Status()
	if status.SoftRequirements != nil {
		newNodeReadyCondition.Message = fmt.Sprintf("%s. WARNING: %s", newNodeReadyCondition.Message, status.SoftRequirements.Error())
	}

	readyConditionUpdated := false
	needToRecordEvent := false
	for i := range node.Status.Conditions {
		if node.Status.Conditions[i].Type == api.NodeReady {
			if node.Status.Conditions[i].Status == newNodeReadyCondition.Status {
				newNodeReadyCondition.LastTransitionTime = node.Status.Conditions[i].LastTransitionTime
			} else {
				newNodeReadyCondition.LastTransitionTime = currentTime
				needToRecordEvent = true
			}
			node.Status.Conditions[i] = newNodeReadyCondition
			readyConditionUpdated = true
			break
		}
	}
	if !readyConditionUpdated {
		newNodeReadyCondition.LastTransitionTime = currentTime
		node.Status.Conditions = append(node.Status.Conditions, newNodeReadyCondition)
	}
	if needToRecordEvent {
		if newNodeReadyCondition.Status == api.ConditionTrue {
			kl.recordNodeStatusEvent(api.EventTypeNormal, kubecontainer.NodeReady)
		} else {
			kl.recordNodeStatusEvent(api.EventTypeNormal, kubecontainer.NodeNotReady)
		}
	}
}

// Set OODcondition for the node.
func (kl *Kubelet) setNodeOODCondition(node *api.Node) {
	currentTime := unversioned.NewTime(kl.clock.Now())
	var nodeOODCondition *api.NodeCondition

	// Check if NodeOutOfDisk condition already exists and if it does, just pick it up for update.
	for i := range node.Status.Conditions {
		if node.Status.Conditions[i].Type == api.NodeOutOfDisk {
			nodeOODCondition = &node.Status.Conditions[i]
		}
	}

	newOODCondition := false
	// If the NodeOutOfDisk condition doesn't exist, create one.
	if nodeOODCondition == nil {
		nodeOODCondition = &api.NodeCondition{
			Type:   api.NodeOutOfDisk,
			Status: api.ConditionUnknown,
		}
		// nodeOODCondition cannot be appended to node.Status.Conditions here because it gets
		// copied to the slice. So if we append nodeOODCondition to the slice here none of the
		// updates we make to nodeOODCondition below are reflected in the slice.
		newOODCondition = true
	}

	// Update the heartbeat time irrespective of all the conditions.
	nodeOODCondition.LastHeartbeatTime = currentTime

	// Note: The conditions below take care of the case when a new NodeOutOfDisk condition is
	// created and as well as the case when the condition already exists. When a new condition
	// is created its status is set to api.ConditionUnknown which matches either
	// nodeOODCondition.Status != api.ConditionTrue or
	// nodeOODCondition.Status != api.ConditionFalse in the conditions below depending on whether
	// the kubelet is out of disk or not.
	if kl.isOutOfDisk() {
		if nodeOODCondition.Status != api.ConditionTrue {
			nodeOODCondition.Status = api.ConditionTrue
			nodeOODCondition.Reason = "KubeletOutOfDisk"
			nodeOODCondition.Message = "out of disk space"
			nodeOODCondition.LastTransitionTime = currentTime
			kl.recordNodeStatusEvent(api.EventTypeNormal, "NodeOutOfDisk")
		}
	} else {
		if nodeOODCondition.Status != api.ConditionFalse {
			// Update the out of disk condition when the condition status is unknown even if we
			// are within the outOfDiskTransitionFrequency duration. We do this to set the
			// condition status correctly at kubelet startup.
			if nodeOODCondition.Status == api.ConditionUnknown || kl.clock.Since(nodeOODCondition.LastTransitionTime.Time) >= kl.outOfDiskTransitionFrequency {
				nodeOODCondition.Status = api.ConditionFalse
				nodeOODCondition.Reason = "KubeletHasSufficientDisk"
				nodeOODCondition.Message = "kubelet has sufficient disk space available"
				nodeOODCondition.LastTransitionTime = currentTime
				kl.recordNodeStatusEvent(api.EventTypeNormal, "NodeHasSufficientDisk")
			} else {
				glog.Infof("Node condition status for OutOfDisk is false, but last transition time is less than %s", kl.outOfDiskTransitionFrequency)
			}
		}
	}

	if newOODCondition {
		node.Status.Conditions = append(node.Status.Conditions, *nodeOODCondition)
	}
}

// Maintains Node.Spec.Unschedulable value from previous run of tryUpdateNodeStatus()
var oldNodeUnschedulable bool

// record if node schedulable change.
func (kl *Kubelet) recordNodeSchedulableEvent(node *api.Node) {
	if oldNodeUnschedulable != node.Spec.Unschedulable {
		if node.Spec.Unschedulable {
			kl.recordNodeStatusEvent(api.EventTypeNormal, kubecontainer.NodeNotSchedulable)
		} else {
			kl.recordNodeStatusEvent(api.EventTypeNormal, kubecontainer.NodeSchedulable)
		}
		oldNodeUnschedulable = node.Spec.Unschedulable
	}
}

// setNodeStatus fills in the Status fields of the given Node, overwriting
// any fields that are currently set.
// TODO(madhusudancs): Simplify the logic for setting node conditions and
// refactor the node status condtion code out to a different file.
func (kl *Kubelet) setNodeStatus(node *api.Node) error {
	for _, f := range kl.setNodeStatusFuncs {
		if err := f(node); err != nil {
			return err
		}
	}
	return nil
}

// defaultNodeStatusFuncs is a factory that generates the default set of setNodeStatus funcs
func (kl *Kubelet) defaultNodeStatusFuncs() []func(*api.Node) error {
	// initial set of node status update handlers, can be modified by Option's
	withoutError := func(f func(*api.Node)) func(*api.Node) error {
		return func(n *api.Node) error {
			f(n)
			return nil
		}
	}
	return []func(*api.Node) error{
		kl.setNodeAddress,
		withoutError(kl.setNodeStatusInfo),
		withoutError(kl.setNodeOODCondition),
		withoutError(kl.setNodeReadyCondition),
		withoutError(kl.recordNodeSchedulableEvent),
	}
}

// SetNodeStatus returns a functional Option that adds the given node status update handler to the Kubelet
func SetNodeStatus(f func(*api.Node) error) Option {
	return func(k *Kubelet) {
		k.setNodeStatusFuncs = append(k.setNodeStatusFuncs, f)
	}
}

// tryUpdateNodeStatus tries to update node status to master. If ReconcileCBR0
// is set, this function will also confirm that cbr0 is configured correctly.
func (kl *Kubelet) tryUpdateNodeStatus() error {
	node, err := kl.kubeClient.Core().Nodes().Get(kl.nodeName)
	if err != nil {
		return fmt.Errorf("error getting node %q: %v", kl.nodeName, err)
	}
	if node == nil {
		return fmt.Errorf("no node instance returned for %q", kl.nodeName)
	}
	// Flannel is the authoritative source of pod CIDR, if it's running.
	// This is a short term compromise till we get flannel working in
	// reservation mode.
	if kl.flannelExperimentalOverlay {
		flannelPodCIDR := kl.runtimeState.podCIDR()
		if node.Spec.PodCIDR != flannelPodCIDR {
			node.Spec.PodCIDR = flannelPodCIDR
			glog.Infof("Updating podcidr to %v", node.Spec.PodCIDR)
			if updatedNode, err := kl.kubeClient.Core().Nodes().Update(node); err != nil {
				glog.Warningf("Failed to update podCIDR: %v", err)
			} else {
				// Update the node resourceVersion so the status update doesn't fail.
				node = updatedNode
			}
		}
	} else if kl.reconcileCIDR {
		kl.updatePodCIDR(node.Spec.PodCIDR)
	}

	if err := kl.setNodeStatus(node); err != nil {
		return err
	}
	// Update the current status on the API server
	_, err = kl.kubeClient.Core().Nodes().UpdateStatus(node)
	return err
}

// GetPhase returns the phase of a pod given its container info.
// This func is exported to simplify integration with 3rd party kubelet
// integrations like kubernetes-mesos.
func GetPhase(spec *api.PodSpec, info []api.ContainerStatus) api.PodPhase {
	running := 0
	waiting := 0
	stopped := 0
	failed := 0
	succeeded := 0
	unknown := 0
	for _, container := range spec.Containers {
		containerStatus, ok := api.GetContainerStatus(info, container.Name)
		if !ok {
			unknown++
			continue
		}

		switch {
		case containerStatus.State.Running != nil:
			running++
		case containerStatus.State.Terminated != nil:
			stopped++
			if containerStatus.State.Terminated.ExitCode == 0 {
				succeeded++
			} else {
				failed++
			}
		case containerStatus.State.Waiting != nil:
			if containerStatus.LastTerminationState.Terminated != nil {
				stopped++
			} else {
				waiting++
			}
		default:
			unknown++
		}
	}

	switch {
	case waiting > 0:
		glog.V(5).Infof("pod waiting > 0, pending")
		// One or more containers has not been started
		return api.PodPending
	case running > 0 && unknown == 0:
		// All containers have been started, and at least
		// one container is running
		return api.PodRunning
	case running == 0 && stopped > 0 && unknown == 0:
		// All containers are terminated
		if spec.RestartPolicy == api.RestartPolicyAlways {
			// All containers are in the process of restarting
			return api.PodRunning
		}
		if stopped == succeeded {
			// RestartPolicy is not Always, and all
			// containers are terminated in success
			return api.PodSucceeded
		}
		if spec.RestartPolicy == api.RestartPolicyNever {
			// RestartPolicy is Never, and all containers are
			// terminated with at least one in failure
			return api.PodFailed
		}
		// RestartPolicy is OnFailure, and at least one in failure
		// and in the process of restarting
		return api.PodRunning
	default:
		glog.V(5).Infof("pod default case, pending")
		return api.PodPending
	}
}

// generateAPIPodStatus creates the final API pod status for a pod, given the
// internal pod status.
func (kl *Kubelet) generateAPIPodStatus(pod *api.Pod, podStatus *kubecontainer.PodStatus) api.PodStatus {
	glog.V(3).Infof("Generating status for %q", format.Pod(pod))

	// check if an internal module has requested the pod is evicted.
	for _, podSyncHandler := range kl.PodSyncHandlers {
		if result := podSyncHandler.ShouldEvict(pod); result.Evict {
			return api.PodStatus{
				Phase:   api.PodFailed,
				Reason:  result.Reason,
				Message: result.Message,
			}
		}
	}

	// TODO: Consider include the container information.
	// TODO: move this into a sync/evictor
	if kl.pastActiveDeadline(pod) {
		reason := "DeadlineExceeded"
		kl.recorder.Eventf(pod, api.EventTypeNormal, reason, "Pod was active on the node longer than specified deadline")
		return api.PodStatus{
			Phase:   api.PodFailed,
			Reason:  reason,
			Message: "Pod was active on the node longer than specified deadline"}
	}

	s := kl.convertStatusToAPIStatus(pod, podStatus)

	// Assume info is ready to process
	spec := &pod.Spec
	s.Phase = GetPhase(spec, s.ContainerStatuses)
	kl.probeManager.UpdatePodStatus(pod.UID, s)
	s.Conditions = append(s.Conditions, status.GeneratePodReadyCondition(spec, s.ContainerStatuses, s.Phase))
	// s (the PodStatus we are creating) will not have a PodScheduled condition yet, because converStatusToAPIStatus()
	// does not create one. If the existing PodStatus has a PodScheduled condition, then copy it into s and make sure
	// it is set to true. If the existing PodStatus does not have a PodScheduled condition, then create one that is set to true.
	if _, oldPodScheduled := api.GetPodCondition(&pod.Status, api.PodScheduled); oldPodScheduled != nil {
		s.Conditions = append(s.Conditions, *oldPodScheduled)
	}
	api.UpdatePodCondition(&pod.Status, &api.PodCondition{
		Type:   api.PodScheduled,
		Status: api.ConditionTrue,
	})

	if !kl.standaloneMode {
		hostIP, err := kl.GetHostIP()
		if err != nil {
			glog.V(4).Infof("Cannot get host IP: %v", err)
		} else {
			s.HostIP = hostIP.String()
			if podUsesHostNetwork(pod) && s.PodIP == "" {
				s.PodIP = hostIP.String()
			}
		}
	}

	return *s
}

// convertStatusToAPIStatus creates an api PodStatus for the given pod from
// the given internal pod status.  It is purely transformative and does not
// alter the kubelet state at all.
func (kl *Kubelet) convertStatusToAPIStatus(pod *api.Pod, podStatus *kubecontainer.PodStatus) *api.PodStatus {
	var apiPodStatus api.PodStatus
	uid := pod.UID
	apiPodStatus.PodIP = podStatus.IP

	convertContainerStatus := func(cs *kubecontainer.ContainerStatus) *api.ContainerStatus {
		cid := cs.ID.String()
		status := &api.ContainerStatus{
			Name:         cs.Name,
			RestartCount: int32(cs.RestartCount),
			Image:        cs.Image,
			ImageID:      cs.ImageID,
			ContainerID:  cid,
		}
		switch cs.State {
		case kubecontainer.ContainerStateRunning:
			status.State.Running = &api.ContainerStateRunning{StartedAt: unversioned.NewTime(cs.StartedAt)}
		case kubecontainer.ContainerStateExited:
			status.State.Terminated = &api.ContainerStateTerminated{
				ExitCode:    int32(cs.ExitCode),
				Reason:      cs.Reason,
				Message:     cs.Message,
				StartedAt:   unversioned.NewTime(cs.StartedAt),
				FinishedAt:  unversioned.NewTime(cs.FinishedAt),
				ContainerID: cid,
			}
		default:
			status.State.Waiting = &api.ContainerStateWaiting{}
		}
		return status
	}

	// Fetch old containers statuses from old pod status.
	oldStatuses := make(map[string]api.ContainerStatus, len(pod.Spec.Containers))
	for _, status := range pod.Status.ContainerStatuses {
		oldStatuses[status.Name] = status
	}

	// Set all container statuses to default waiting state
	statuses := make(map[string]*api.ContainerStatus, len(pod.Spec.Containers))
	defaultWaitingState := api.ContainerState{Waiting: &api.ContainerStateWaiting{Reason: "ContainerCreating"}}
	for _, container := range pod.Spec.Containers {
		status := &api.ContainerStatus{
			Name:  container.Name,
			Image: container.Image,
			State: defaultWaitingState,
		}
		// Apply some values from the old statuses as the default values.
		if oldStatus, found := oldStatuses[container.Name]; found {
			status.RestartCount = oldStatus.RestartCount
			status.LastTerminationState = oldStatus.LastTerminationState
		}
		statuses[container.Name] = status
	}

	// Make the latest container status comes first.
	sort.Sort(sort.Reverse(kubecontainer.SortContainerStatusesByCreationTime(podStatus.ContainerStatuses)))

	// Set container statuses according to the statuses seen in pod status
	containerSeen := map[string]int{}
	for _, cStatus := range podStatus.ContainerStatuses {
		cName := cStatus.Name
		if _, ok := statuses[cName]; !ok {
			// This would also ignore the infra container.
			continue
		}
		if containerSeen[cName] >= 2 {
			continue
		}
		status := convertContainerStatus(cStatus)
		if containerSeen[cName] == 0 {
			statuses[cName] = status
		} else {
			statuses[cName].LastTerminationState = status.State
		}
		containerSeen[cName] = containerSeen[cName] + 1
	}

	// Handle the containers failed to be started, which should be in Waiting state.
	for _, container := range pod.Spec.Containers {
		// If a container should be restarted in next syncpod, it is *Waiting*.
		if !kubecontainer.ShouldContainerBeRestarted(&container, pod, podStatus) {
			continue
		}
		status := statuses[container.Name]
		reason, message, ok := kl.reasonCache.Get(uid, container.Name)
		if !ok {
			// In fact, we could also apply Waiting state here, but it is less informative,
			// and the container will be restarted soon, so we prefer the original state here.
			// Note that with the current implementation of ShouldContainerBeRestarted the original state here
			// could be:
			//   * Waiting: There is no associated historical container and start failure reason record.
			//   * Terminated: The container is terminated.
			continue
		}
		if status.State.Terminated != nil {
			status.LastTerminationState = status.State
		}
		status.State = api.ContainerState{
			Waiting: &api.ContainerStateWaiting{
				Reason:  reason.Error(),
				Message: message,
			},
		}
		statuses[container.Name] = status
	}

	apiPodStatus.ContainerStatuses = make([]api.ContainerStatus, 0)
	for _, status := range statuses {
		apiPodStatus.ContainerStatuses = append(apiPodStatus.ContainerStatuses, *status)
	}

	// Sort the container statuses since clients of this interface expect the list
	// of containers in a pod has a deterministic order.
	sort.Sort(kubetypes.SortedContainerStatuses(apiPodStatus.ContainerStatuses))
	return &apiPodStatus
}

// Returns logs of current machine.
func (kl *Kubelet) ServeLogs(w http.ResponseWriter, req *http.Request) {
	// TODO: whitelist logs we are willing to serve
	kl.logServer.ServeHTTP(w, req)
}

// findContainer finds and returns the container with the given pod ID, full name, and container name.
// It returns nil if not found.
func (kl *Kubelet) findContainer(podFullName string, podUID types.UID, containerName string) (*kubecontainer.Container, error) {
	pods, err := kl.containerRuntime.GetPods(false)
	if err != nil {
		return nil, err
	}
	pod := kubecontainer.Pods(pods).FindPod(podFullName, podUID)
	return pod.FindContainerByName(containerName), nil
}

// Run a command in a container, returns the combined stdout, stderr as an array of bytes
func (kl *Kubelet) RunInContainer(podFullName string, podUID types.UID, containerName string, cmd []string) ([]byte, error) {
	podUID = kl.podManager.TranslatePodUID(podUID)

	container, err := kl.findContainer(podFullName, podUID, containerName)
	if err != nil {
		return nil, err
	}
	if container == nil {
		return nil, fmt.Errorf("container not found (%q)", containerName)
	}

	var buffer bytes.Buffer
	output := ioutils.WriteCloserWrapper(&buffer)
	err = kl.runner.ExecInContainer(container.ID, cmd, nil, output, output, false)
	if err != nil {
		return nil, err
	}

	return buffer.Bytes(), nil
}

// ExecInContainer executes a command in a container, connecting the supplied
// stdin/stdout/stderr to the command's IO streams.
func (kl *Kubelet) ExecInContainer(podFullName string, podUID types.UID, containerName string, cmd []string, stdin io.Reader, stdout, stderr io.WriteCloser, tty bool) error {
	podUID = kl.podManager.TranslatePodUID(podUID)

	container, err := kl.findContainer(podFullName, podUID, containerName)
	if err != nil {
		return err
	}
	if container == nil {
		return fmt.Errorf("container not found (%q)", containerName)
	}
	return kl.runner.ExecInContainer(container.ID, cmd, stdin, stdout, stderr, tty)
}

// AttachContainer uses the container runtime to attach the given streams to
// the given container.
func (kl *Kubelet) AttachContainer(podFullName string, podUID types.UID, containerName string, stdin io.Reader, stdout, stderr io.WriteCloser, tty bool) error {
	podUID = kl.podManager.TranslatePodUID(podUID)

	container, err := kl.findContainer(podFullName, podUID, containerName)
	if err != nil {
		return err
	}
	if container == nil {
		return fmt.Errorf("container not found (%q)", containerName)
	}
	return kl.containerRuntime.AttachContainer(container.ID, stdin, stdout, stderr, tty)
}

// PortForward connects to the pod's port and copies data between the port
// and the stream.
func (kl *Kubelet) PortForward(podFullName string, podUID types.UID, port uint16, stream io.ReadWriteCloser) error {
	podUID = kl.podManager.TranslatePodUID(podUID)

	pods, err := kl.containerRuntime.GetPods(false)
	if err != nil {
		return err
	}
	pod := kubecontainer.Pods(pods).FindPod(podFullName, podUID)
	if pod.IsEmpty() {
		return fmt.Errorf("pod not found (%q)", podFullName)
	}
	return kl.runner.PortForward(&pod, port, stream)
}

// BirthCry sends an event that the kubelet has started up.
func (kl *Kubelet) BirthCry() {
	// Make an event that kubelet restarted.
	kl.recorder.Eventf(kl.nodeRef, api.EventTypeNormal, kubecontainer.StartingKubelet, "Starting kubelet.")
}

// StreamingConnectionIdleTimeout returns the timeout for streaming connections to the HTTP server.
func (kl *Kubelet) StreamingConnectionIdleTimeout() time.Duration {
	return kl.streamingConnectionIdleTimeout
}

// ResyncInterval returns the interval used for periodic syncs.
func (kl *Kubelet) ResyncInterval() time.Duration {
	return kl.resyncInterval
}

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

// ListenAndServeReadOnly runs the kubelet HTTP server in read-only mode.
func (kl *Kubelet) ListenAndServeReadOnly(address net.IP, port uint) {
	server.ListenAndServeKubeletReadOnlyServer(kl, kl.resourceAnalyzer, address, port, kl.containerRuntime)
}

// updatePodCIDR updates the pod CIDR in the runtime state if it is different
// from the current CIDR.
func (kl *Kubelet) updatePodCIDR(cidr string) {
	if kl.runtimeState.podCIDR() == cidr {
		return
	}

	glog.Infof("Setting Pod CIDR: %v -> %v", kl.runtimeState.podCIDR(), cidr)
	kl.runtimeState.setPodCIDR(cidr)

	if kl.networkPlugin != nil {
		details := make(map[string]interface{})
		details[network.NET_PLUGIN_EVENT_POD_CIDR_CHANGE_DETAIL_CIDR] = cidr
		kl.networkPlugin.Event(network.NET_PLUGIN_EVENT_POD_CIDR_CHANGE, details)
	}
}

// shapingEnabled returns whether traffic shaping is enabled.
func (kl *Kubelet) shapingEnabled() bool {
	// Disable shaping if a network plugin is defined and supports shaping
	if kl.networkPlugin != nil && kl.networkPlugin.Capabilities().Has(network.NET_PLUGIN_CAPABILITY_SHAPING) {
		return false
	}
	return true
}