kube-aggregator: periodically resync local specs

Co-authored-by: Dr. Stefan Schimanski <stefan.schimanski@gmail.com>

staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/aggregator/aggregator.go

@@ -19,6 +19,7 @@ package aggregator
 import (
 	"fmt"
 	"net/http"
+	"strings"
 	"sync"
 	"time"
 
@@ -40,17 +41,35 @@ type SpecAggregator interface {
 	UpdateAPIServiceSpec(apiServiceName string, spec *spec.Swagger, etag string) error
 	RemoveAPIServiceSpec(apiServiceName string) error
 	GetAPIServiceInfo(apiServiceName string) (handler http.Handler, etag string, exists bool)
+	GetAPIServiceNames() []string
 }
 
 const (
 	aggregatorUser                = "system:aggregator"
 	specDownloadTimeout           = 60 * time.Second
-	localDelegateChainNamePattern = "k8s_internal_local_delegation_chain_%010d"
+	localDelegateChainNamePrefix  = "k8s_internal_local_delegation_chain_"
+	localDelegateChainNamePattern = localDelegateChainNamePrefix + "%010d"
 
 	// A randomly generated UUID to differentiate local and remote eTags.
 	locallyGeneratedEtagPrefix = "\"6E8F849B434D4B98A569B9D7718876E9-"
 )
 
+// IsLocalAPIService returns true for local specs from delegates.
+func IsLocalAPIService(apiServiceName string) bool {
+	return strings.HasPrefix(apiServiceName, localDelegateChainNamePrefix)
+}
+
+// GetAPIServicesName returns the names of APIServices recorded in specAggregator.openAPISpecs.
+// We use this function to pass the names of local APIServices to the controller in this package,
+// so that the controller can periodically sync the OpenAPI spec from delegation API servers.
+func (s *specAggregator) GetAPIServiceNames() []string {
+	names := make([]string, len(s.openAPISpecs))
+	for key := range s.openAPISpecs {
+		names = append(names, key)
+	}
+	return names
+}
+
 // BuildAndRegisterAggregator registered OpenAPI aggregator handler. This function is not thread safe as it only being called on startup.
 func BuildAndRegisterAggregator(downloader *Downloader, delegationTarget server.DelegationTarget, webServices []*restful.WebService,
 	config *common.Config, pathHandler common.PathHandler) (SpecAggregator, error) {
@@ -161,6 +180,7 @@ func (s *specAggregator) buildOpenAPISpec() (specToReturn *spec.Swagger, err err
 			return nil, err
 		}
 	}
+
 	return specToReturn, nil
 }
 
@@ -179,7 +199,14 @@ func (s *specAggregator) updateOpenAPISpec() error {
 // tryUpdatingServiceSpecs tries updating openAPISpecs map with specified specInfo, and keeps the map intact
 // if the update fails.
 func (s *specAggregator) tryUpdatingServiceSpecs(specInfo *openAPISpecInfo) error {
+	if specInfo == nil {
+		return fmt.Errorf("invalid input: specInfo must be non-nil")
+	}
 	orgSpecInfo, exists := s.openAPISpecs[specInfo.apiService.Name]
+	// Skip aggregation if OpenAPI spec didn't change
+	if exists && orgSpecInfo != nil && orgSpecInfo.etag == specInfo.etag {
+		return nil
+	}
 	s.openAPISpecs[specInfo.apiService.Name] = specInfo
 	if err := s.updateOpenAPISpec(); err != nil {
 		if exists {

staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/controller.go

@@ -30,8 +30,9 @@ import (
 )
 
 const (
-	successfulUpdateDelay   = time.Minute
-	failedUpdateMaxExpDelay = time.Hour
+	successfulUpdateDelay      = time.Minute
+	successfulUpdateDelayLocal = time.Second
+	failedUpdateMaxExpDelay    = time.Hour
 )
 
 type syncAction int
@@ -64,6 +65,11 @@ func NewAggregationController(downloader *aggregator.Downloader, openAPIAggregat
 
 	c.syncHandler = c.sync
 
+	// update each service at least once, also those which are not coming from APIServices, namely local services
+	for _, name := range openAPIAggregationManager.GetAPIServiceNames() {
+		c.queue.AddAfter(name, time.Second)
+	}
+
 	return c
 }
 
@@ -104,8 +110,13 @@ func (c *AggregationController) processNextWorkItem() bool {
 
 	switch action {
 	case syncRequeue:
-		klog.Infof("OpenAPI AggregationController: action for item %s: Requeue.", key)
-		c.queue.AddAfter(key, successfulUpdateDelay)
+		if aggregator.IsLocalAPIService(key.(string)) {
+			klog.V(7).Infof("OpenAPI AggregationController: action for local item %s: Requeue after %s.", key, successfulUpdateDelayLocal)
+			c.queue.AddAfter(key, successfulUpdateDelayLocal)
+		} else {
+			klog.V(7).Infof("OpenAPI AggregationController: action for item %s: Requeue.", key)
+			c.queue.AddAfter(key, successfulUpdateDelay)
+		}
 	case syncRequeueRateLimited:
 		klog.Infof("OpenAPI AggregationController: action for item %s: Rate Limited Requeue.", key)
 		c.queue.AddRateLimited(key)