added experimental backup optimizations

core/backup_restore.go

@@ -0,0 +1,196 @@
+package core
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"runtime"
+
+	"github.com/pocketbase/pocketbase/tools/archive"
+	"github.com/pocketbase/pocketbase/tools/osutils"
+	"github.com/pocketbase/pocketbase/tools/security"
+)
+
+// RestoreBackup restores the backup with the specified name and restarts
+// the current running application process.
+//
+// NB! This feature is experimental and currently is expected to work only on UNIX based systems.
+//
+// To safely perform the restore it is recommended to have free disk space
+// for at least 2x the size of the restored pb_data backup.
+//
+// The performed steps are:
+//
+//  1. Download the backup with the specified name in a temp location
+//     (this is in case of S3; otherwise it creates a temp copy of the zip)
+//
+//  2. Extract the backup in a temp directory inside the app "pb_data"
+//     (eg. "pb_data/.pb_temp_to_delete/pb_restore").
+//
+//  3. Move the current app "pb_data" content (excluding the local backups and the special temp dir)
+//     under another temp sub dir that will be deleted on the next app start up
+//     (eg. "pb_data/.pb_temp_to_delete/old_pb_data").
+//     This is because on some environments it may not be allowed
+//     to delete the currently open "pb_data" files.
+//
+//  4. Move the extracted dir content to the app "pb_data".
+//
+//  5. Restart the app (on successful app bootstrap it will also remove the old pb_data).
+//
+// If a failure occur during the restore process the dir changes are reverted.
+// If for whatever reason the revert is not possible, it panics.
+//
+// Note that if your pb_data has custom network mounts as subdirectories, then
+// it is possible the restore to fail during the `os.Rename` operations
+// (see https://github.com/pocketbase/pocketbase/issues/4647).
+func (app *BaseApp) RestoreBackup(ctx context.Context, name string) error {
+	if app.Store().Has(StoreKeyActiveBackup) {
+		return errors.New("try again later - another backup/restore operation has already been started")
+	}
+
+	app.Store().Set(StoreKeyActiveBackup, name)
+	defer app.Store().Remove(StoreKeyActiveBackup)
+
+	event := new(BackupEvent)
+	event.App = app
+	event.Context = ctx
+	event.Name = name
+	// default root dir entries to exclude from the backup restore
+	event.Exclude = []string{LocalBackupsDirName, LocalTempDirName, LocalAutocertCacheDirName, lostFoundDirName}
+
+	return app.OnBackupRestore().Trigger(event, func(e *BackupEvent) error {
+		if runtime.GOOS == "windows" {
+			return errors.New("restore is not supported on Windows")
+		}
+
+		// make sure that the special temp directory exists
+		// note: it needs to be inside the current pb_data to avoid "cross-device link" errors
+		localTempDir := filepath.Join(e.App.DataDir(), LocalTempDirName)
+		if err := os.MkdirAll(localTempDir, os.ModePerm); err != nil {
+			return fmt.Errorf("failed to create a temp dir: %w", err)
+		}
+
+		fsys, err := e.App.NewBackupsFilesystem()
+		if err != nil {
+			return err
+		}
+		defer fsys.Close()
+
+		fsys.SetContext(e.Context)
+
+		if ok, _ := fsys.Exists(name); !ok {
+			return fmt.Errorf("missing or invalid backup file %q to restore", name)
+		}
+
+		extractedDataDir := filepath.Join(localTempDir, "pb_restore_"+security.PseudorandomString(8))
+		defer os.RemoveAll(extractedDataDir)
+
+		// extract the zip
+		if e.App.Settings().Backups.S3.Enabled {
+			br, err := fsys.GetReader(name)
+			if err != nil {
+				return err
+			}
+			defer br.Close()
+
+			// create a temp zip file from the blob.Reader and try to extract it
+			tempZip, err := os.CreateTemp(localTempDir, "pb_restore_zip")
+			if err != nil {
+				return err
+			}
+			defer os.Remove(tempZip.Name())
+			defer tempZip.Close() // note: this technically shouldn't be necessary but it is here to workaround platforms discrepancies
+
+			_, err = io.Copy(tempZip, br)
+			if err != nil {
+				return err
+			}
+
+			err = archive.Extract(tempZip.Name(), extractedDataDir)
+			if err != nil {
+				return err
+			}
+
+			// remove the temp zip file since we no longer need it
+			// (this is in case the app restarts and the defer calls are not called)
+			_ = tempZip.Close()
+			err = os.Remove(tempZip.Name())
+			if err != nil {
+				e.App.Logger().Warn(
+					"[RestoreBackup] Failed to remove the temp zip backup file",
+					slog.String("file", tempZip.Name()),
+					slog.String("error", err.Error()),
+				)
+			}
+		} else {
+			// manually construct the local path to avoid creating a copy of the zip file
+			// since the blob reader currently doesn't implement ReaderAt
+			zipPath := filepath.Join(e.App.DataDir(), LocalBackupsDirName, filepath.Base(name))
+
+			err = archive.Extract(zipPath, extractedDataDir)
+			if err != nil {
+				return err
+			}
+		}
+
+		// ensure that at least a database file exists
+		extractedDB := filepath.Join(extractedDataDir, "data.db")
+		if _, err := os.Stat(extractedDB); err != nil {
+			return fmt.Errorf("data.db file is missing or invalid: %w", err)
+		}
+
+		oldTempDataDir := filepath.Join(localTempDir, "old_pb_data_"+security.PseudorandomString(8))
+
+		replaceErr := e.App.RunInTransaction(func(txApp App) error {
+			return txApp.AuxRunInTransaction(func(txApp App) error {
+				// move the current pb_data content to a special temp location
+				// that will hold the old data between dirs replace
+				// (the temp dir will be automatically removed on the next app start)
+				if err := osutils.MoveDirContent(txApp.DataDir(), oldTempDataDir, e.Exclude...); err != nil {
+					return fmt.Errorf("failed to move the current pb_data content to a temp location: %w", err)
+				}
+
+				// move the extracted archive content to the app's pb_data
+				if err := osutils.MoveDirContent(extractedDataDir, txApp.DataDir(), e.Exclude...); err != nil {
+					return fmt.Errorf("failed to move the extracted archive content to pb_data: %w", err)
+				}
+
+				return nil
+			})
+		})
+		if replaceErr != nil {
+			return replaceErr
+		}
+
+		revertDataDirChanges := func() error {
+			return e.App.RunInTransaction(func(txApp App) error {
+				return txApp.AuxRunInTransaction(func(txApp App) error {
+					if err := osutils.MoveDirContent(txApp.DataDir(), extractedDataDir, e.Exclude...); err != nil {
+						return fmt.Errorf("failed to revert the extracted dir change: %w", err)
+					}
+
+					if err := osutils.MoveDirContent(oldTempDataDir, txApp.DataDir(), e.Exclude...); err != nil {
+						return fmt.Errorf("failed to revert old pb_data dir change: %w", err)
+					}
+
+					return nil
+				})
+			})
+		}
+
+		// restart the app
+		if err := e.App.Restart(); err != nil {
+			if revertErr := revertDataDirChanges(); revertErr != nil {
+				panic(revertErr)
+			}
+
+			return fmt.Errorf("failed to restart the app process: %w", err)
+		}
+
+		return nil
+	})
+}