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這篇文章主要講解了“Kubernetes Job Controller怎么構造”，文中的講解內容簡單清晰，易于學習與理解，下面請大家跟著小編的思路慢慢深入，一起來研究和學習“Kubernetes Job Controller怎么構造”吧！
廢話不多說，先把完整流程貼出來。
type JobController struct {
kubeClient clientset.Interface
podControl controller.PodControlInterface
// To allow injection of updateJobStatus for testing.
updateHandler func(job *batch.Job) error
syncHandler func(jobKey string) (bool, error)
// podStoreSynced returns true if the pod store has been synced at least once.
// Added as a member to the struct to allow injection for testing.
podStoreSynced cache.InformerSynced
// jobStoreSynced returns true if the job store has been synced at least once.
// Added as a member to the struct to allow injection for testing.
jobStoreSynced cache.InformerSynced
// A TTLCache of pod creates/deletes each rc expects to see
expectations controller.ControllerExpectationsInterface
// A store of jobs
jobLister batchv1listers.JobLister
// A store of pods, populated by the podController
podStore corelisters.PodLister
// Jobs that need to be updated
queue workqueue.RateLimitingInterface
recorder record.EventRecorder
}
func NewJobController(podInformer coreinformers.PodInformer, jobInformer batchinformers.JobInformer, kubeClient clientset.Interface) *JobController {
eventBroadcaster := record.NewBroadcaster()
eventBroadcaster.StartLogging(glog.Infof)
// TODO: remove the wrapper when every clients have moved to use the clientset.
eventBroadcaster.StartRecordingToSink(&v1core.EventSinkImpl{Interface: v1core.New(kubeClient.CoreV1().RESTClient()).Events("")})
if kubeClient != nil && kubeClient.CoreV1().RESTClient().GetRateLimiter() != nil {
metrics.RegisterMetricAndTrackRateLimiterUsage("job_controller", kubeClient.CoreV1().RESTClient().GetRateLimiter())
}
jm := &JobController{
kubeClient: kubeClient,
podControl: controller.RealPodControl{
KubeClient: kubeClient,
Recorder: eventBroadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: "job-controller"}),
},
expectations: controller.NewControllerExpectations(),
queue: workqueue.NewNamedRateLimitingQueue(workqueue.NewItemExponentialFailureRateLimiter(DefaultJobBackOff, MaxJobBackOff), "job"),
recorder: eventBroadcaster.NewRecorder(scheme.Scheme, v1.EventSource{Component: "job-controller"}),
}
jobInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: jm.enqueueController,
UpdateFunc: jm.updateJob,
DeleteFunc: jm.enqueueController,
})
jm.jobLister = jobInformer.Lister()
jm.jobStoreSynced = jobInformer.Informer().HasSynced
podInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: jm.addPod,
UpdateFunc: jm.updatePod,
DeleteFunc: jm.deletePod,
})
jm.podStore = podInformer.Lister()
jm.podStoreSynced = podInformer.Informer().HasSynced
jm.updateHandler = jm.updateJobStatus
jm.syncHandler = jm.syncJob
return jm
}構造JobController，并初始化相關數據，比如rate limiter queue;
watch pod and job object;
注冊podInformer的add/del/update EventHandler；
注冊jobInformer的add/del/update EventHandler;
注冊updataHandler為updateJobStatus，用來更新Job狀態；
注冊syncHandler為syncJob，用來進行處理queue中的Job；
// Run the main goroutine responsible for watching and syncing jobs.
func (jm *JobController) Run(workers int, stopCh <-chan struct{}) {
defer utilruntime.HandleCrash()
defer jm.queue.ShutDown()
glog.Infof("Starting job controller")
defer glog.Infof("Shutting down job controller")
if !controller.WaitForCacheSync("job", stopCh, jm.podStoreSynced, jm.jobStoreSynced) {
return
}
for i := 0; i < workers; i++ {
go wait.Until(jm.worker, time.Second, stopCh)
}
<-stopCh
}// worker runs a worker thread that just dequeues items, processes them, and marks them done.
// It enforces that the syncHandler is never invoked concurrently with the same key.
func (jm *JobController) worker() {
for jm.processNextWorkItem() {
}
}
func (jm *JobController) processNextWorkItem() bool {
key, quit := jm.queue.Get()
if quit {
return false
}
defer jm.queue.Done(key)
forget, err := jm.syncHandler(key.(string))
if err == nil {
if forget {
jm.queue.Forget(key)
}
return true
}
utilruntime.HandleError(fmt.Errorf("Error syncing job: %v", err))
jm.queue.AddRateLimited(key)
return true
}WaitForCacheSync等待jobController cache同步；
啟動5個goruntine，每個協程分別執行worker，每個worker執行完后等待1s，繼續執行，如此循環；
worker負責從從queue中get job key，對每個job，調用syncJob進行同步，如果syncJob成功，則forget the job（其實就是讓rate limiter 停止tracking it），否則將該key再次加入到queue中，等待下次sync。
// syncJob will sync the job with the given key if it has had its expectations fulfilled, meaning
// it did not expect to see any more of its pods created or deleted. This function is not meant to be invoked
// concurrently with the same key.
func (jm *JobController) syncJob(key string) (bool, error) {
startTime := time.Now()
defer func() {
glog.V(4).Infof("Finished syncing job %q (%v)", key, time.Now().Sub(startTime))
}()
ns, name, err := cache.SplitMetaNamespaceKey(key)
if err != nil {
return false, err
}
if len(ns) == 0 || len(name) == 0 {
return false, fmt.Errorf("invalid job key %q: either namespace or name is missing", key)
}
sharedJob, err := jm.jobLister.Jobs(ns).Get(name)
if err != nil {
if errors.IsNotFound(err) {
glog.V(4).Infof("Job has been deleted: %v", key)
jm.expectations.DeleteExpectations(key)
return true, nil
}
return false, err
}
job := *sharedJob
// if job was finished previously, we don't want to redo the termination
if IsJobFinished(&job) {
return true, nil
}
// retrieve the previous number of retry
previousRetry := jm.queue.NumRequeues(key)
// Check the expectations of the job before counting active pods, otherwise a new pod can sneak in
// and update the expectations after we've retrieved active pods from the store. If a new pod enters
// the store after we've checked the expectation, the job sync is just deferred till the next relist.
jobNeedsSync := jm.expectations.SatisfiedExpectations(key)
pods, err := jm.getPodsForJob(&job)
if err != nil {
return false, err
}
activePods := controller.FilterActivePods(pods)
active := int32(len(activePods))
succeeded, failed := getStatus(pods)
conditions := len(job.Status.Conditions)
// job first start
if job.Status.StartTime == nil {
now := metav1.Now()
job.Status.StartTime = &now
// enqueue a sync to check if job past ActiveDeadlineSeconds
if job.Spec.ActiveDeadlineSeconds != nil {
glog.V(4).Infof("Job %s have ActiveDeadlineSeconds will sync after %d seconds",
key, *job.Spec.ActiveDeadlineSeconds)
jm.queue.AddAfter(key, time.Duration(*job.Spec.ActiveDeadlineSeconds)*time.Second)
}
}
var manageJobErr error
jobFailed := false
var failureReason string
var failureMessage string
jobHaveNewFailure := failed > job.Status.Failed
// check if the number of failed jobs increased since the last syncJob
if jobHaveNewFailure && (int32(previousRetry)+1 > *job.Spec.BackoffLimit) {
jobFailed = true
failureReason = "BackoffLimitExceeded"
failureMessage = "Job has reach the specified backoff limit"
} else if pastActiveDeadline(&job) {
jobFailed = true
failureReason = "DeadlineExceeded"
failureMessage = "Job was active longer than specified deadline"
}
if jobFailed {
errCh := make(chan error, active)
jm.deleteJobPods(&job, activePods, errCh)
select {
case manageJobErr = <-errCh:
if manageJobErr != nil {
break
}
default:
}
// update status values accordingly
failed += active
active = 0
job.Status.Conditions = append(job.Status.Conditions, newCondition(batch.JobFailed, failureReason, failureMessage))
jm.recorder.Event(&job, v1.EventTypeWarning, failureReason, failureMessage)
} else {
if jobNeedsSync && job.DeletionTimestamp == nil {
active, manageJobErr = jm.manageJob(activePods, succeeded, &job)
}
completions := succeeded
complete := false
if job.Spec.Completions == nil {
// This type of job is complete when any pod exits with success.
// Each pod is capable of
// determining whether or not the entire Job is done. Subsequent pods are
// not expected to fail, but if they do, the failure is ignored. Once any
// pod succeeds, the controller waits for remaining pods to finish, and
// then the job is complete.
if succeeded > 0 && active == 0 {
complete = true
}
} else {
// Job specifies a number of completions. This type of job signals
// success by having that number of successes. Since we do not
// start more pods than there are remaining completions, there should
// not be any remaining active pods once this count is reached.
if completions >= *job.Spec.Completions {
complete = true
if active > 0 {
jm.recorder.Event(&job, v1.EventTypeWarning, "TooManyActivePods", "Too many active pods running after completion count reached")
}
if completions > *job.Spec.Completions {
jm.recorder.Event(&job, v1.EventTypeWarning, "TooManySucceededPods", "Too many succeeded pods running after completion count reached")
}
}
}
if complete {
job.Status.Conditions = append(job.Status.Conditions, newCondition(batch.JobComplete, "", ""))
now := metav1.Now()
job.Status.CompletionTime = &now
}
}
forget := false
// no need to update the job if the status hasn't changed since last time
if job.Status.Active != active || job.Status.Succeeded != succeeded || job.Status.Failed != failed || len(job.Status.Conditions) != conditions {
job.Status.Active = active
job.Status.Succeeded = succeeded
job.Status.Failed = failed
if err := jm.updateHandler(&job); err != nil {
return false, err
}
if jobHaveNewFailure && !IsJobFinished(&job) {
// returning an error will re-enqueue Job after the backoff period
return false, fmt.Errorf("failed pod(s) detected for job key %q", key)
}
forget = true
}
return forget, manageJobErr
}從Indexer中查找指定的Job是否存在，如果不存在，則從expectations中刪除該job，流程結束返回true。否則繼續下面流程。
根據JobCondition Complete or Failed判斷Job是否Finished，如果Finished，則流程結束返回true，否則繼續下面流程。
調用SatisfiedExpectations，如果ControlleeExpectations中待add和del都<=0，或者expectations已經超過5分鐘沒更新過了，則返回jobNeedsSync=true，表示需要進行一次manageJob了。
對于那些第一次啟動的jobs (StartTime==nil), 需要把設置StartTime，并且如果ActiveDeadlineSeconds不為空，則經過ActiveDeadlineSeconds后再次把該job加入到queue中進行sync。
獲取該job管理的所有pods，過濾出activePods，計算出actived,successed,failed pods的數量。如果failed > job.Status.Failed，說明該job又有新failed Pods了，則jobHaveNewFailure為true。
如果jobHaveNewFailure，并且queue記錄的該job retry次數加1，比job.Spec.BackoffLimit(默認為6)，則表示該job BackoffLimitExceeded，jobFailed。如果job StartTime到現在為止的歷時>=ActiveDeadlineSeconds，則表示該job DeadlineExceeded，jobFailed。
如果jobFailed，則用sync.WaitGroup并發等待刪除所有的前面過濾出來的activePods，刪除成功，則failed += acitve, active = 0, 并設置Condition Failed為true。
如果job not failed, jobNeedSync為true，并且job的DeletionTimestamp為空（沒有標記為刪除），則調用manageJob對Job管理的pods根據復雜的策略進行add or del。
如果job not failed且job.Spec.Completions為nil，表示This type of job is complete when any pod exits with success。因此如果succeeded > 0 && active == 0，則表示job completed。
如果如果job not failed且job.Spec.Completions不為nil，表示This type of job signals success by having that number of successes。因此如果succeeded >= job.Spec.Completions，則表示job completed。
如果job completed，則更新其Conditions Complete為true，并設置CompletionTime。
接下來invoke updateJobStatus更新etcd中job狀態，如果更新失敗，則返回false，該job將再次加入queue。如果jobHaveNewFailure為true，并且Job Condition顯示該Job not Finished，則返回false，該job將再次加入queue。
// manageJob is the core method responsible for managing the number of running
// pods according to what is specified in the job.Spec.
// Does NOT modify <activePods>.
func (jm *JobController) manageJob(activePods []*v1.Pod, succeeded int32, job *batch.Job) (int32, error) {
var activeLock sync.Mutex
active := int32(len(activePods))
parallelism := *job.Spec.Parallelism
jobKey, err := controller.KeyFunc(job)
if err != nil {
utilruntime.HandleError(fmt.Errorf("Couldn't get key for job %#v: %v", job, err))
return 0, nil
}
var errCh chan error
if active > parallelism {
diff := active - parallelism
errCh = make(chan error, diff)
jm.expectations.ExpectDeletions(jobKey, int(diff))
glog.V(4).Infof("Too many pods running job %q, need %d, deleting %d", jobKey, parallelism, diff)
// Sort the pods in the order such that not-ready < ready, unscheduled
// < scheduled, and pending < running. This ensures that we delete pods
// in the earlier stages whenever possible.
sort.Sort(controller.ActivePods(activePods))
active -= diff
wait := sync.WaitGroup{}
wait.Add(int(diff))
for i := int32(0); i < diff; i++ {
go func(ix int32) {
defer wait.Done()
if err := jm.podControl.DeletePod(job.Namespace, activePods[ix].Name, job); err != nil {
defer utilruntime.HandleError(err)
// Decrement the expected number of deletes because the informer won't observe this deletion
glog.V(2).Infof("Failed to delete %v, decrementing expectations for job %q/%q", activePods[ix].Name, job.Namespace, job.Name)
jm.expectations.DeletionObserved(jobKey)
activeLock.Lock()
active++
activeLock.Unlock()
errCh <- err
}
}(i)
}
wait.Wait()
} else if active < parallelism {
wantActive := int32(0)
if job.Spec.Completions == nil {
// Job does not specify a number of completions. Therefore, number active
// should be equal to parallelism, unless the job has seen at least
// once success, in which leave whatever is running, running.
if succeeded > 0 {
wantActive = active
} else {
wantActive = parallelism
}
} else {
// Job specifies a specific number of completions. Therefore, number
// active should not ever exceed number of remaining completions.
wantActive = *job.Spec.Completions - succeeded
if wantActive > parallelism {
wantActive = parallelism
}
}
diff := wantActive - active
if diff < 0 {
utilruntime.HandleError(fmt.Errorf("More active than wanted: job %q, want %d, have %d", jobKey, wantActive, active))
diff = 0
}
jm.expectations.ExpectCreations(jobKey, int(diff))
errCh = make(chan error, diff)
glog.V(4).Infof("Too few pods running job %q, need %d, creating %d", jobKey, wantActive, diff)
active += diff
wait := sync.WaitGroup{}
// Batch the pod creates. Batch sizes start at SlowStartInitialBatchSize
// and double with each successful iteration in a kind of "slow start".
// This handles attempts to start large numbers of pods that would
// likely all fail with the same error. For example a project with a
// low quota that attempts to create a large number of pods will be
// prevented from spamming the API service with the pod create requests
// after one of its pods fails. Conveniently, this also prevents the
// event spam that those failures would generate.
for batchSize := int32(integer.IntMin(int(diff), controller.SlowStartInitialBatchSize)); diff > 0; batchSize = integer.Int32Min(2*batchSize, diff) {
errorCount := len(errCh)
wait.Add(int(batchSize))
for i := int32(0); i < batchSize; i++ {
go func() {
defer wait.Done()
err := jm.podControl.CreatePodsWithControllerRef(job.Namespace, &job.Spec.Template, job, metav1.NewControllerRef(job, controllerKind))
if err != nil && errors.IsTimeout(err) {
// Pod is created but its initialization has timed out.
// If the initialization is successful eventually, the
// controller will observe the creation via the informer.
// If the initialization fails, or if the pod keeps
// uninitialized for a long time, the informer will not
// receive any update, and the controller will create a new
// pod when the expectation expires.
return
}
if err != nil {
defer utilruntime.HandleError(err)
// Decrement the expected number of creates because the informer won't observe this pod
glog.V(2).Infof("Failed creation, decrementing expectations for job %q/%q", job.Namespace, job.Name)
jm.expectations.CreationObserved(jobKey)
activeLock.Lock()
active--
activeLock.Unlock()
errCh <- err
}
}()
}
wait.Wait()
// any skipped pods that we never attempted to start shouldn't be expected.
skippedPods := diff - batchSize
if errorCount < len(errCh) && skippedPods > 0 {
glog.V(2).Infof("Slow-start failure. Skipping creation of %d pods, decrementing expectations for job %q/%q", skippedPods, job.Namespace, job.Name)
active -= skippedPods
for i := int32(0); i < skippedPods; i++ {
// Decrement the expected number of creates because the informer won't observe this pod
jm.expectations.CreationObserved(jobKey)
}
// The skipped pods will be retried later. The next controller resync will
// retry the slow start process.
break
}
diff -= batchSize
}
}
select {
case err := <-errCh:
// all errors have been reported before, we only need to inform the controller that there was an error and it should re-try this job once more next time.
if err != nil {
return active, err
}
default:
}
return active, nil
}如果active > job.Spec.Parallelism, 表示要scale down：
計算active與parallelism的差值diff，修改ControllerExpectations中該job的dels為diff，表示要刪除diff這么多的pod。
計算active與parallelism的差值diff，修改ControllerExpectations中該job的dels為diff，表示要刪除diff這么多的pod。
將activePods中的Pods按照not-ready < ready, unscheduled < scheduled, pending < running進行排序，確保先刪除stage越早的pods。
更新active (active減去diff），用sync.WaitGroup并發等待刪除etcd中那些Pods。如果刪除某個Pod失敗，active要加1，expectations中dels要減1.
返回active
如果active < job.Spec.Parallelism， 表示要scale up：
如果job.Spec.Completions為nil，且succeeded大于0，則diff設為0；如果job.Spec.Completions為nil，但successed = 0，則diff為 parallelism-active；如果job.Spec.Completions不為nil，則diff為max(job.Spec.Completions - succeeded，parallelim) - active；
修改ControllerExpectations中該job的adds為diff，表示要新增diff這么多的pod。
更新active (active加上diff），用sync.WaitGroup分批的創建Pods，第一批創建1個(代碼寫死SlowStartInitialBatchSize = 1)，第二批創建2，然后4,8,16...這樣下去，但是每次不能超過diff的值。每一批創建pod后，注意更新diff的值（減去batchsize）。如果某一批創建過程Pods中存在失敗情況，則更新active和expectations中adds，且不進行后續未啟動的批量創建pods行為。
如果active == job.Spec.Parallelism，返回active。
感謝各位的閱讀，以上就是“Kubernetes Job Controller怎么構造”的內容了，經過本文的學習后，相信大家對Kubernetes Job Controller怎么構造這一問題有了更深刻的體會，具體使用情況還需要大家實踐驗證。這里是億速云，小編將為大家推送更多相關知識點的文章，歡迎關注！
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