Check disk space before backing up / restoring

pkg/admin/autorecovery/restore.go

@@ -58,9 +58,17 @@ func (m *Manager) PerformRestore() error {
 		  RENAME    $STORAGE/$PREVIOUSLY_RESTORED -> $STORAGE/restored/$PREVIOUSLY_RESTORED
 	*/
 
+	if err := data.CheckIfEnoughSpaceToRestore(m.storage.GetBackupPath(restoreCandidate.Name())); err != nil {
+		return err
+	}
+
 	// Copies/creations into intermediate destinations
 	var oldData *data.AtomicDirCopy
 	if m.saveFailed {
+		if err := data.CheckIfEnoughSpaceToBackUp(string(m.storage)); err != nil {
+			return err
+		}
+
 		oldDataBackupName, err := GetBackupName()
 		if err != nil {
 			return err

pkg/admin/data/data_manager.go

@@ -108,6 +108,10 @@ func (dm *manager) Backup(name BackupName) (string, error) {
 		klog.InfoS("Created backup storage directory", "path", dm.storage)
 	}
 
+	if err := CheckIfEnoughSpaceToBackUp(string(dm.storage)); err != nil {
+		return "", err
+	}
+
 	dest := dm.GetBackupPath(name)
 	if err := copyPath(config.DataDir, dest); err != nil {
 		return "", err
@@ -141,6 +145,10 @@ func (dm *manager) Restore(name BackupName) error {
 		return fmt.Errorf("%q is not a valid MicroShift backup: %w", path, err)
 	}
 
+	if err := CheckIfEnoughSpaceToRestore(path); err != nil {
+		return err
+	}
+
 	tmp := fmt.Sprintf("%s.saved", config.DataDir)
 	klog.InfoS("Renaming existing data dir", "data", config.DataDir, "renamedTo", tmp)
 	if err := os.Rename(config.DataDir, tmp); err != nil {

pkg/admin/data/disk_space.go

@@ -0,0 +1,97 @@
+package data
+
+import (
+	"fmt"
+	"io/fs"
+	"path/filepath"
+	"syscall"
+
+	"github.com/openshift/microshift/pkg/config"
+
+	"k8s.io/klog/v2"
+)
+
+func GetSizeOfMicroShiftData() (uint64, error) {
+	return GetSizeOfDir(config.DataDir)
+}
+
+func GetSizeOfDir(path string) (uint64, error) {
+	var size int64
+	err := filepath.Walk(path, func(path string, info fs.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if !info.IsDir() {
+			size += info.Size()
+		}
+		return nil
+	})
+	if err != nil {
+		return 0, fmt.Errorf("failed to get size of %q: %w", path, err)
+	}
+	klog.Infof("Calculated size of %q: %vM", path, size/1024/1024)
+	return uint64(size), nil
+}
+
+func GetAvailableDiskSpace(path string) (uint64, error) {
+	var stat syscall.Statfs_t
+	if err := syscall.Statfs(path, &stat); err != nil {
+		return 0, fmt.Errorf("failed to get available disk space of %q: %w", path, err)
+	}
+	available := stat.Bavail * uint64(stat.Bsize)
+	klog.Infof("Calculated available disk space for %q: %vM", path, available/1024/1024)
+	return available, nil
+}
+
+// CheckIfEnoughSpaceToRestore performs a naive check if there is enough
+// disk space on /var/lib filesystem to restore the backup.
+// It does not accomodate for potential Copy-on-Write disk savings.
+func CheckIfEnoughSpaceToRestore(backupPath string) error {
+	backupSize, err := GetSizeOfDir(backupPath)
+	if err != nil {
+		return err
+	}
+
+	// Restore process: renames MicroShift data dir, copies backup into place, deletes renamed copy hence the /var/lib
+	// needs extra space before old MicroShift data is removed.
+	availableSpace, err := GetAvailableDiskSpace("/var/lib")
+	if err != nil {
+		return err
+	}
+
+	if availableSpace < backupSize {
+		return fmt.Errorf(
+			"not enough disk space in /var/lib to restore the backup: required=%vM available=%vM",
+			backupSize/1024/1024,
+			availableSpace/1024/1024,
+		)
+	}
+
+	return nil
+}
+
+// CheckIfEnoughSpaceToBackUp performs a naive check if there is enough
+// disk space on a filesystem holding the backups for another backup of MicroShift data.
+// It does not accomodate for potential Copy-on-Write disk savings.
+func CheckIfEnoughSpaceToBackUp(storage string) error {
+	dataSize, err := GetSizeOfMicroShiftData()
+	if err != nil {
+		return err
+	}
+
+	availableSpace, err := GetAvailableDiskSpace(storage)
+	if err != nil {
+		return err
+	}
+
+	if availableSpace < dataSize {
+		return fmt.Errorf(
+			"not enough disk space in %q to create a backup: required=%vM available=%vM",
+			storage,
+			dataSize/1024/1024,
+			availableSpace/1024/1024,
+		)
+	}
+
+	return nil
+}