Enhances the decision to take full snapshot during startup to avoid m…

…issing of any full-snapshot.

pkg/miscellaneous/miscellaneous.go

@@ -520,3 +520,16 @@ func ParsePeerURL(initialAdvertisePeerURLs, podName string) (string, error) {
 	domaiName := fmt.Sprintf("%s.%s.%s", tokens[1], tokens[2], "svc")
 	return fmt.Sprintf("%s://%s.%s:%s", tokens[0], podName, domaiName, tokens[3]), nil
 }
+
+// GetPrevDayScheduledSnapTime returns the previous day schedule snapshot time.
+func GetPrevDayScheduledSnapTime(nextSnapSchedule time.Time) time.Time {
+	return time.Date(
+		nextSnapSchedule.Year(),
+		nextSnapSchedule.Month(),
+		nextSnapSchedule.Day()-1,
+		nextSnapSchedule.Hour(),
+		nextSnapSchedule.Minute(),
+		nextSnapSchedule.Second(),
+		nextSnapSchedule.Nanosecond(),
+		nextSnapSchedule.Location())
+}

pkg/server/backuprestoreserver.go

@@ -362,16 +362,12 @@ func (b *BackupRestoreServer) runEtcdProbeLoopWithSnapshotter(ctx context.Contex
 			// the delta snapshot memory limit), after which a full snapshot
 			// is taken and the regular snapshot schedule comes into effect.
 
-			// TODO: write code to find out if prev full snapshot is older than it is
-			// supposed to be, according to the given cron schedule, instead of the
-			// hard-coded "24 hours" full snapshot interval
-
 			// Temporary fix for missing alternate full snapshots for Gardener shoots
 			// with hibernation schedule set: change value from 24 ot 23.5 to
 			// accommodate for slight pod spin-up delays on shoot wake-up
 			const recentFullSnapshotPeriodInHours = 23.5
 			initialDeltaSnapshotTaken = false
-			if ssr.PrevFullSnapshot != nil && !ssr.PrevFullSnapshot.IsFinal && time.Since(ssr.PrevFullSnapshot.CreatedOn).Hours() <= recentFullSnapshotPeriodInHours {
+			if ssr.PrevFullSnapshot != nil && !ssr.PrevFullSnapshot.IsFinal && !ssr.IsScheduledFullSnapshotMissed() {
 				ssrStopped, err := ssr.CollectEventsSincePrevSnapshot(ssrStopCh)
 				if ssrStopped {
 					b.logger.Info("Snapshotter stopped.")

pkg/snapshot/snapshotter/snapshotter.go

@@ -42,6 +42,10 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 )
 
+const (
+	recentFullSnapshotPeriodInHours = 23.5
+)
+
 var (
 	emptyStruct   struct{}
 	snapstoreHash = make(map[string]interface{})
@@ -104,7 +108,7 @@ func NewSnapshotter(logger *logrus.Entry, config *brtypes.SnapshotterConfig, sto
 	sdl, err := cron.ParseStandard(config.FullSnapshotSchedule)
 	if err != nil {
 		// Ideally this should be validated before.
-		return nil, fmt.Errorf("invalid schedule provied %s : %v", config.FullSnapshotSchedule, err)
+		return nil, fmt.Errorf("invalid full snapshot schedule provided %s : %v", config.FullSnapshotSchedule, err)
 	}
 
 	var prevSnapshot *brtypes.Snapshot
@@ -473,12 +477,12 @@ func (ssr *Snapshotter) TakeDeltaSnapshot() (*brtypes.Snapshot, error) {
 	defer rc.Close()
 
 	if err := ssr.store.Save(*snap, rc); err != nil {
-		timeTaken := time.Now().Sub(startTime).Seconds()
+		timeTaken := time.Since(startTime).Seconds()
 		metrics.SnapshotDurationSeconds.With(prometheus.Labels{metrics.LabelKind: brtypes.SnapshotKindDelta, metrics.LabelSucceeded: metrics.ValueSucceededFalse}).Observe(timeTaken)
 		ssr.logger.Errorf("Error saving delta snapshots. %v", err)
 		return nil, err
 	}
-	timeTaken := time.Now().Sub(startTime).Seconds()
+	timeTaken := time.Since(startTime).Seconds()
 	metrics.SnapshotDurationSeconds.With(prometheus.Labels{metrics.LabelKind: brtypes.SnapshotKindDelta, metrics.LabelSucceeded: metrics.ValueSucceededTrue}).Observe(timeTaken)
 	logrus.Infof("Total time to save delta snapshot: %f seconds.", timeTaken)
 	ssr.prevSnapshot = snap
@@ -740,3 +744,20 @@ func (ssr *Snapshotter) checkSnapstoreSecretUpdate() bool {
 	snapstoreHash[ssr.snapstoreConfig.Provider] = newSnapstoreSecretHash
 	return true
 }
+
+// IsScheduledFullSnapshotMissed checked whether the last scheduled full-snapshot was missed or not.
+func (ssr *Snapshotter) IsScheduledFullSnapshotMissed() bool {
+	if time.Since(ssr.PrevFullSnapshot.CreatedOn).Hours() > recentFullSnapshotPeriodInHours {
+		return true
+	}
+
+	now := time.Now()
+	nextSnapSchedule := ssr.schedule.Next(now)
+	timeToTakeNextSnap := nextSnapSchedule.Sub(now)
+
+	if miscellaneous.GetPrevDayScheduledSnapTime(nextSnapSchedule) == ssr.PrevFullSnapshot.CreatedOn {
+		return false
+	}
+
+	return timeToTakeNextSnap.Hours()+time.Since(ssr.PrevFullSnapshot.CreatedOn).Hours() > recentFullSnapshotPeriodInHours
+}