Wait for initial cache to sync before starting autoscaling

cluster-autoscaler/main.go

@@ -23,6 +23,7 @@ import (
 	"net/http"
 	"os"
 	"os/signal"
+	"reflect"
 	"strconv"
 	"strings"
 	"syscall"
@@ -608,10 +609,54 @@ func buildAutoscaler(debuggingSnapshotter debuggingsnapshot.DebuggingSnapshotter
 	// additional informers might have been registered in the factory during NewAutoscaler.
 	stop := make(chan struct{})
 	informerFactory.Start(stop)
-
+	klog.V(1).Info("Started shared informer factory, waiting for initial cache sync")
+
+	syncStart := time.Now()
+	allSynced := false
+	for !allSynced {
+		syncStatus := waitForCacheSyncWithTimeout(informerFactory, time.Second*10)
+		var missing []string
+		for t, synced := range syncStatus {
+			if !synced {
+				missing = append(missing, t.String())
+			}
+		}
+		if len(missing) > 0 {
+			klog.V(4).Infof("Still waiting to sync the following caches: %s", strings.Join(missing, ","))
+		} else {
+			allSynced = true
+		}
+	}
+	klog.V(1).Infof("Shared informer factory initialized, took %v", time.Since(syncStart))
 	return autoscaler, nil
 }
 
+// waitForCacheSyncWithTimeout waits up to the specified time for the informerFactory's caches to be synced;
+// Returns before the timeout if the caches are synced sooner.
+func waitForCacheSyncWithTimeout(informerFactory informers.SharedInformerFactory, timeout time.Duration) map[reflect.Type]bool {
+	interruptCh := make(chan struct{})
+	defer close(interruptCh)
+
+	doneCh := make(chan map[reflect.Type]bool)
+	defer close(doneCh)
+
+	go func() {
+		syncStatus := informerFactory.WaitForCacheSync(interruptCh)
+		doneCh <- syncStatus
+	}()
+
+	for {
+		select {
+		// WaitForCacheSync has returned; return the resulting status
+		case syncStatus := <-doneCh:
+			return syncStatus
+		// The timeout has expired, signal the interrupt channel and then read the result from the done channel
+		case <-time.After(timeout):
+			interruptCh <- struct{}{}
+		}
+	}
+}
+
 func run(healthCheck *metrics.HealthCheck, debuggingSnapshotter debuggingsnapshot.DebuggingSnapshotter) {
 	metrics.RegisterAll(*emitPerNodeGroupMetrics)