sched: always set the leader election parameters

Because of a overlook, we used to set the leader election
params only if replicas > 1 was requested. This left
the key *and default* corner case of replicas=1 with
compiled in defaults, which are questionable at best
and most likely harmful for our use case.

Make sure to always set sane parameters, obviously
taking into account the user desires from the spec
(Replicas field).

Add more logs to make troubleshooting easier

Signed-off-by: Francesco Romani <[email protected]>

controllers/numaresourcesscheduler_controller.go

@@ -264,23 +264,29 @@ func unpackAPIResyncPeriod(reconcilePeriod *metav1.Duration) time.Duration {
 
 func configParamsFromSchedSpec(schedSpec nropv1.NUMAResourcesSchedulerSpec, cacheResyncPeriod time.Duration, namespace string) k8swgmanifests.ConfigParams {
 	resyncPeriod := int64(cacheResyncPeriod.Seconds())
+	// if no actual replicas are required, leader election is unnecessary, so
+	// we force it to off to reduce the background noise.
+	// note: the api validation/normalization layer must ensure this value is != nil
+	leaderElect := (*schedSpec.Replicas > 1)
 
 	params := k8swgmanifests.ConfigParams{
 		ProfileName: schedSpec.SchedulerName,
 		Cache: &k8swgmanifests.ConfigCacheParams{
 			ResyncPeriodSeconds: &resyncPeriod,
 		},
 		ScoringStrategy: &k8swgmanifests.ScoringStrategyParams{},
-	}
-
-	if schedSpec.Replicas != nil && *schedSpec.Replicas > 1 {
-		params.LeaderElection = &k8swgmanifests.LeaderElectionParams{
-			LeaderElect:       true,
+		LeaderElection: &k8swgmanifests.LeaderElectionParams{
+			// Make sure to always set explicitly the value and override the configmap defaults.
+			LeaderElect: leaderElect,
+			// unconditionally set those to make sure
+			// to play nice with the cluster and the main scheduler
 			ResourceNamespace: namespace,
 			ResourceName:      leaderElectionResourceName,
-		}
+		},
 	}
 
+	klog.V(2).InfoS("setting leader election parameters", dumpLeaderElectionParams(params.LeaderElection)...)
+
 	var foreignPodsDetect string
 	var resyncMethod string = k8swgmanifests.CacheResyncAutodetect
 	var informerMode string
@@ -317,7 +323,7 @@ func configParamsFromSchedSpec(schedSpec nropv1.NUMAResourcesSchedulerSpec, cach
 	params.Cache.ResyncMethod = &resyncMethod
 	params.Cache.ForeignPodsDetectMode = &foreignPodsDetect
 	params.Cache.InformerMode = &informerMode
-	klog.InfoS("setting cache parameters", dumpConfigCacheParams(params.Cache)...)
+	klog.V(2).InfoS("setting cache parameters", dumpConfigCacheParams(params.Cache)...)
 
 	return params
 }
@@ -331,6 +337,14 @@ func dumpConfigCacheParams(ccp *k8swgmanifests.ConfigCacheParams) []interface{}
 	}
 }
 
+func dumpLeaderElectionParams(lep *k8swgmanifests.LeaderElectionParams) []interface{} {
+	return []interface{}{
+		"leaderElect", lep.LeaderElect,
+		"resourceNamespace", lep.ResourceNamespace,
+		"resourceName", lep.ResourceName,
+	}
+}
+
 func strInt64Ptr(ip *int64) string {
 	if ip == nil {
 		return "N/A"