feat: optional MySQL/MariaDB database driver for deployments that cannot use local SQLite

internal/infrastructure/persistence/database/backupRetention.go

@@ -0,0 +1,55 @@
+package database
+
+import (
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+	"time"
+)
+
+type backupFile struct {
+	path     string
+	modified time.Time
+}
+
+func newBackupTarget(directory string, now time.Time, extension string) (string, error) {
+	if err := os.MkdirAll(directory, os.ModePerm); err != nil {
+		return "", err
+	}
+	target := filepath.Join(directory, backupFilePrefix+now.UTC().Format(backupTimeLayout)+extension)
+	if _, err := os.Stat(target); err == nil {
+		return "", errBackupExists
+	}
+	return target, nil
+}
+
+func pruneBackups(directory string, extension string) error {
+	entries, err := os.ReadDir(directory)
+	if err != nil {
+		return err
+	}
+	files := make([]backupFile, 0, len(entries))
+	for _, entry := range entries {
+		if entry.IsDir() || !strings.HasSuffix(entry.Name(), extension) {
+			continue
+		}
+		info, err := entry.Info()
+		if err != nil {
+			return err
+		}
+		files = append(files, backupFile{path: filepath.Join(directory, entry.Name()), modified: info.ModTime()})
+	}
+	slices.SortFunc(files, func(a, b backupFile) int {
+		if byTime := b.modified.Compare(a.modified); byTime != 0 {
+			return byTime
+		}
+		return strings.Compare(b.path, a.path)
+	})
+	for _, stale := range files[min(backupsToKeep, len(files)):] {
+		if err := os.Remove(stale.path); err != nil {
+			return err
+		}
+	}
+	return nil
+}