Limit ResourceQuota LIST requests to times when informer is not synced

This should reduce the number of slow (100ms) LIST requests when there
are no ResourceQuota objects present in the namespace. The behavior
stays virtually the same.

Kubernetes-commit: 1ac9e213a8dcd23e706f112f2dc3f8447eee33c9

Author: AwesomePatrol

pkg/admission/plugin/resourcequota/admission.go

@@ -114,7 +114,9 @@ func (a *QuotaAdmission) SetExternalKubeClientSet(client kubernetes.Interface) {
 
 // SetExternalKubeInformerFactory registers an informer factory into QuotaAdmission
 func (a *QuotaAdmission) SetExternalKubeInformerFactory(f informers.SharedInformerFactory) {
-	a.quotaAccessor.lister = f.Core().V1().ResourceQuotas().Lister()
+	quotas := f.Core().V1().ResourceQuotas()
+	a.quotaAccessor.lister = quotas.Lister()
+	a.quotaAccessor.hasSynced = quotas.Informer().HasSynced
 }
 
 // SetQuotaConfiguration assigns and initializes configuration and evaluator for QuotaAdmission
@@ -144,6 +146,9 @@ func (a *QuotaAdmission) ValidateInitialization() error {
 	if a.quotaAccessor.lister == nil {
 		return fmt.Errorf("missing quotaAccessor.lister")
 	}
+	if a.quotaAccessor.hasSynced == nil {
+		return fmt.Errorf("missing quotaAccessor.hasSynced")
+	}
 	if a.quotaConfiguration == nil {
 		return fmt.Errorf("missing quotaConfiguration")
 	}

pkg/admission/plugin/resourcequota/resource_access.go

@@ -48,6 +48,9 @@ type quotaAccessor struct {
 	// lister can list/get quota objects from a shared informer's cache
 	lister corev1listers.ResourceQuotaLister
 
+	// hasSynced indicates whether the lister has completed its initial sync
+	hasSynced func() bool
+
 	// liveLookups holds the last few live lookups we've done to help ammortize cost on repeated lookup failures.
 	// This lets us handle the case of latent caches, by looking up actual results for a namespace on cache miss/no results.
 	// We track the lookup result here so that for repeated requests, we don't look it up very often.
@@ -112,8 +115,8 @@ func (e *quotaAccessor) GetQuotas(namespace string) ([]corev1.ResourceQuota, err
 		return nil, fmt.Errorf("error resolving quota: %v", err)
 	}
 
-	// if there are no items held in our indexer, check our live-lookup LRU, if that misses, do the live lookup to prime it.
-	if len(items) == 0 {
+	// if there are no items held in our unsynced lister, check our live-lookup LRU, if that misses, do the live lookup to prime it.
+	if len(items) == 0 && !e.hasSynced() {
 		lruItemObj, ok := e.liveLookupCache.Get(namespace)
 		if !ok || lruItemObj.(liveLookupEntry).expiry.Before(time.Now()) {
 			// use singleflight.Group to avoid flooding the apiserver with repeated

pkg/admission/plugin/resourcequota/resource_access_test.go

@@ -97,6 +97,7 @@ func TestLRUCacheLookup(t *testing.T) {
 			accessor, _ := newQuotaAccessor()
 			accessor.client = kubeClient
 			accessor.lister = informerFactory.Core().V1().ResourceQuotas().Lister()
+			accessor.hasSynced = func() bool { return false }
 			accessor.liveLookupCache = liveLookupCache
 
 			for _, q := range tc.cacheInput {
@@ -151,6 +152,7 @@ func TestGetQuotas(t *testing.T) {
 	accessor, _ := newQuotaAccessor()
 	accessor.client = kubeClient
 	accessor.lister = informerFactory.Core().V1().ResourceQuotas().Lister()
+	accessor.hasSynced = func() bool { return false }
 
 	kubeClient.AddReactor("list", "resourcequotas", func(action core.Action) (bool, runtime.Object, error) {
 		switch action.GetNamespace() {