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fix: metric lag calculation for update events #1244

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merged 1 commit into from
Dec 9, 2024
Merged

fix: metric lag calculation for update events #1244

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29 changes: 18 additions & 11 deletions scrapers/kubernetes/informers.go
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Original file line number Diff line number Diff line change
Expand Up @@ -87,7 +87,7 @@ type SharedInformerManager struct {
type DeleteObjHandler func(ctx context.Context, id string) error

func (t *SharedInformerManager) Register(ctx api.ScrapeContext, watchResource v1.KubernetesResourceToWatch, queue *pq.Queue) error {
start := time.Now()
registrationTime := time.Now()

apiVersion, kind := watchResource.ApiVersion, watchResource.Kind

Expand All @@ -107,6 +107,8 @@ func (t *SharedInformerManager) Register(ctx api.ScrapeContext, watchResource v1
ctx.Logger.V(1).Infof("registering shared informer for: %v", watchResource)
_, err := informer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
AddFunc: func(obj any) {
receivedAt := time.Now().Round(time.Second)

u, err := getUnstructuredFromInformedObj(watchResource, obj)
if err != nil {
ctx.Counter("kubernetes_informer_errors",
Expand All @@ -127,19 +129,24 @@ func (t *SharedInformerManager) Register(ctx api.ScrapeContext, watchResource v1
"type", "add",
"kind", u.GetKind(),
"scraper_id", ctx.ScraperID(),
"valid_timestamp", lo.Ternary(u.GetCreationTimestamp().Time.After(start), "true", "false"),
"valid_timestamp", lo.Ternary(u.GetCreationTimestamp().Time.After(registrationTime), "true", "false"),
).Add(1)

// This is a way to avoid instrumenting old objects so they don't skew the lag time.
if u.GetCreationTimestamp().Time.After(start) {
if u.GetCreationTimestamp().Time.After(registrationTime) {
ctx.Histogram("informer_receive_lag", informerLagBuckets,
"scraper", ctx.ScraperID(),
"kind", watchResource.Kind,
"operation", "add",
).Record(time.Duration(time.Since(u.GetCreationTimestamp().Time).Milliseconds()))
).Record(time.Duration(u.GetCreationTimestamp().Time.Sub(receivedAt).Milliseconds()))
}
},
UpdateFunc: func(oldObj any, newObj any) {
// Kubernetes object timestamps are only precise to the second, so we round
// the current time to the nearest second to avoid incorrectly marking
// timestamps as being in the past due to millisecond differences.
receivedAt := time.Now().UTC().Round(time.Second)

u, err := getUnstructuredFromInformedObj(watchResource, newObj)
if err != nil {
ctx.Counter("kubernetes_informer_errors",
Expand All @@ -155,24 +162,24 @@ func (t *SharedInformerManager) Register(ctx api.ScrapeContext, watchResource v1
ctx.Logger.V(3).Infof("updated: %s %s %s", u.GetUID(), u.GetKind(), u.GetName())
}

lastUpdatedTime := health.GetLastUpdatedTime(u)
lastUpdatedInPast := lastUpdatedTime != nil && lastUpdatedTime.After(u.GetCreationTimestamp().Time) && lastUpdatedTime.Before(start)
if lastUpdatedInPast {
lastUpdatedTime := lo.FromPtr(health.GetLastUpdatedTime(u))
lastUpdatedInFuture := lastUpdatedTime.After(receivedAt)
if !lastUpdatedInFuture {
ctx.Histogram("informer_receive_lag", informerLagBuckets,
"scraper", ctx.ScraperID(),
"kind", watchResource.Kind,
"operation", "update",
).Record(time.Duration(time.Since(*lastUpdatedTime).Milliseconds()))
).Record(time.Duration(receivedAt.Sub(lastUpdatedTime).Milliseconds()))
} else {
ctx.Warnf("%s/%s/%s has last updated time %s into the future. now=%s, lastupdatedTime=%s",
u.GetKind(), u.GetNamespace(), u.GetName(), time.Until(*lastUpdatedTime), start, *lastUpdatedTime)
ctx.Warnf("%s/%s/%s has last updated time %s into the future. receivedAt=%s, lastupdatedTime=%s",
u.GetKind(), u.GetNamespace(), u.GetName(), lastUpdatedTime.Sub(receivedAt), receivedAt, lastUpdatedTime)
}

ctx.Counter("kubernetes_informer_events",
"type", "update",
"kind", u.GetKind(),
"scraper_id", ctx.ScraperID(),
"valid_timestamp", lo.Ternary(lastUpdatedInPast, "true", "false"),
"valid_timestamp", lo.Ternary(!lastUpdatedInFuture, "true", "false"),
).Add(1)

queue.Enqueue(NewQueueItem(u, QueueItemOperationUpdate))
Expand Down
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