Backups: Add worker to create backups in the background #4237 #4243

In the next step, this worker can be configured to automatically create
index and/or album backups at regular intervals.

Signed-off-by: Michael Mayer <michael@photoprism.app>

internal/workers/backup.go

@@ -0,0 +1,89 @@
+package workers
+
+import (
+	"errors"
+	"fmt"
+	"path/filepath"
+	"runtime/debug"
+	"time"
+
+	"github.com/photoprism/photoprism/internal/config"
+	"github.com/photoprism/photoprism/internal/entity"
+	"github.com/photoprism/photoprism/internal/mutex"
+	"github.com/photoprism/photoprism/internal/photoprism"
+)
+
+// Backup represents a background backup worker.
+type Backup struct {
+	conf    *config.Config
+	lastRun time.Time
+}
+
+// NewBackup returns a new Backup worker.
+func NewBackup(conf *config.Config) *Backup {
+	return &Backup{conf: conf}
+}
+
+// Start creates index and album backups based on the current configuration.
+func (w *Backup) Start(index, albums, force bool) (err error) {
+	defer func() {
+		if r := recover(); r != nil {
+			err = fmt.Errorf("backup: %s (worker panic)\nstack: %s", r, debug.Stack())
+			log.Error(err)
+		}
+	}()
+
+	// Return if no backups should be created.
+	if !index && !albums {
+		return nil
+	}
+
+	// Return error if backup worker is already running.
+	if err = mutex.BackupWorker.Start(); err != nil {
+		return err
+	}
+
+	defer mutex.BackupWorker.Stop()
+
+	// Start creating backups.
+	start := time.Now()
+	backupPath := filepath.Join(w.conf.BackupPath(), w.conf.DatabaseDriver())
+
+	if index && albums {
+		log.Infof("backup: creating index and album backups")
+	} else if index {
+		log.Infof("backup: creating index backup")
+	} else if albums {
+		log.Infof("backup: creating album backup")
+	}
+
+	// Create index database backup.
+	if !index {
+		// Skip.
+	} else if err = photoprism.BackupIndex(backupPath, "", false, force); err != nil {
+		log.Errorf("backup: %s (backup index)", err)
+	}
+
+	if mutex.BackupWorker.Canceled() {
+		return errors.New("backup: canceled")
+	}
+
+	// Create album YAML file backup.
+	if !albums {
+		// Skip.
+	} else if count, backupErr := photoprism.BackupAlbums(w.conf.AlbumsPath(), force); backupErr != nil {
+		log.Errorf("backup: %s (backup albums)", backupErr.Error())
+	} else if count > 0 {
+		log.Debugf("backup: %d albums saved as yaml files", count)
+	}
+
+	// Update time when worker was last executed.
+	w.lastRun = entity.TimeStamp()
+
+	elapsed := time.Since(start)
+
+	// Show success message.
+	log.Infof("backup: completed in %s", elapsed)
+
+	return nil
+}