Break out the backup functions of the daemon in prep for S3 support

server/backup/backup_local.go

@@ -0,0 +1,87 @@
+package backup
+
+import (
+	"encoding/hex"
+	"github.com/mholt/archiver/v3"
+	"github.com/pkg/errors"
+	"go.uber.org/zap"
+	"os"
+	"strings"
+	"sync"
+)
+
+// Locates the backup for a server and returns the local path. This will obviously only
+// work if the backup was created as a local backup.
+func LocateLocal(uuid string) (*Backup, os.FileInfo, error) {
+	b := &Backup{
+		Uuid:         uuid,
+		IgnoredFiles: nil,
+	}
+
+	st, err := os.Stat(b.Path())
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if st.IsDir() {
+		return nil, nil, errors.New("invalid archive found; is directory")
+	}
+
+	return b, st, nil
+}
+
+// Generates a backup of the selected files and pushes it to the defined location
+// for this instance.
+func (b *Backup) LocalBackup(dir string) (*ArchiveDetails, error) {
+	if err := archiver.Archive([]string{dir}, b.Path()); err != nil {
+		if strings.HasPrefix(err.Error(), "file already exists") {
+			if rerr := os.Remove(b.Path()); rerr != nil {
+				return nil, errors.WithStack(rerr)
+			}
+
+			// Re-attempt this backup by calling it with the same information.
+			return b.LocalBackup(dir)
+		}
+
+		// If there was some error with the archive, just go ahead and ensure the backup
+		// is completely destroyed at this point. Ignore any errors from this function.
+		os.Remove(b.Path())
+
+		return nil, err
+	}
+
+	wg := sync.WaitGroup{}
+	wg.Add(2)
+
+	var checksum string
+	// Calculate the checksum for the file.
+	go func() {
+		defer wg.Done()
+
+		resp, err := b.Checksum()
+		if err != nil {
+			zap.S().Errorw("failed to calculate checksum for backup", zap.String("backup", b.Uuid), zap.Error(err))
+		}
+
+		checksum = hex.EncodeToString(resp)
+	}()
+
+	var sz int64
+	go func() {
+		defer wg.Done()
+
+		st, err := os.Stat(b.Path())
+		if err != nil {
+			return
+		}
+
+		sz = st.Size()
+	}()
+
+	wg.Wait()
+
+	return &ArchiveDetails{
+		Checksum: checksum,
+		Size:     sz,
+	}, nil
+}