Added KeepHolds so cleaner does not try to destroy snapshots with holds

main.go

@@ -61,6 +61,10 @@ func processAll(now time.Time, conf *conf.Config, zfsExecutor zfs.Executor) ([]z
 			}
 			list.KeepNamed(plan.Protect)
 			list.KeepLatest(plan.Latest)
+			err = list.KeepHolds(zfsExecutor)
+			if err != nil {
+				return nil, err
+			}
 			for _, period := range plan.Periods {
 				start := now.Add(-period.Age)
 				list.Sieve(start, period.Frequency)

main_test.go

@@ -127,6 +127,10 @@ func (t *testExecutor) HasSnapshot(dataset string) (bool, error) {
 	panic("implement me")
 }
 
+func (t *testExecutor) HasHolds(dataset string) (bool, error) {
+	return false, nil
+}
+
 func (t *testExecutor) DestroySnapshot(dataset string) ([]byte, error) {
 	return nil, nil
 }

zfs/SnapshotList.go

@@ -109,6 +109,20 @@ func (l SnapshotList) KeepOldest(num int) {
 	}
 }
 
+// KeepHolds will keep all snapshots with zfs holds on it.
+func (l SnapshotList) KeepHolds(zfsExecutor Executor) error {
+	for _, snapshot := range l {
+		hasHolds, err := zfsExecutor.HasHolds(snapshot.Name)
+		if err != nil {
+			return err
+		}
+		if hasHolds {
+			snapshot.Keep = true
+		}
+	}
+	return nil
+}
+
 // Sieve will mark snapshots to keep according to start time and frequency.
 func (l SnapshotList) Sieve(start time.Time, frequency time.Duration) {
 	// The ZFS resolution on creation time is one second. If we get a frequency

zfs/SnapshotList_test.go

@@ -57,6 +57,10 @@ func (t *testExecutor) HasSnapshot(dataset string) (bool, error) {
 	panic("implement me")
 }
 
+func (t *testExecutor) HasHolds(dataset string) (bool, error) {
+	return false, nil
+}
+
 func (t *testExecutor) DestroySnapshot(dataset string) ([]byte, error) {
 	return nil, nil
 }

zfs/ZfsExecutor.go

@@ -10,6 +10,7 @@ type Executor interface {
 	GetSnapshotList(dataset string) ([]byte, error)
 	GetFilesystems() ([]byte, error)
 	HasSnapshot(dataset string) (bool, error)
+	HasHolds(dataset string) (bool, error)
 	DestroySnapshot(dataset string) ([]byte, error)
 }
 
@@ -62,6 +63,19 @@ func (z *executorImpl) HasSnapshot(dataset string) (bool, error) {
 	return len(output) > 0, nil
 }
 
+func (z *executorImpl) HasHolds(snapshot string) (bool, error) {
+	argsStr := fmt.Sprintf("holds -H %s", snapshot)
+	args := strings.Fields(argsStr)
+	output, err := exec.Command(z.zfsCommandName, args...).Output()
+	if exitError, ok := err.(*exec.ExitError); ok {
+		return false, fmt.Errorf("failed to get snapshot holds to see if the snapshots has any holds: %s error: %s", snapshot, exitError.Stderr)
+	}
+	if err != nil {
+		return false, err
+	}
+	return len(output) != 0, nil
+}
+
 func (z *executorImpl) DestroySnapshot(snapshot string) ([]byte, error) {
 	output, err := exec.Command(z.zfsCommandName, "destroy", snapshot).Output()
 	if exitError, ok := err.(*exec.ExitError); ok {