v0.12.6: fix rsync destination nesting and exclude app-internal DB dumps

Two rsync bugs found during Immich cross-drive backup testing:

Fix 3: Simplified destination path structure in runRsyncBackup.
Old SplitN logic kept "storage/immich" as a subpath, creating redundant
nesting: backups/rsync/immich/storage/immich/<data>. New logic: single
mount → rsync directly into the stack folder; multiple mounts → use
each mount's leaf dir name as subfolder (disambiguated by _N suffix).

Fix 4: Exclude app-internal DB dump files from rsync. Apps like Immich
store periodic pg_dumps in <data>/backups/*.sql.gz. The controller
already handles DB backups via pg_dump — copying them again wastes space.
Added --exclude backups/*.sql.gz/sql/dump to the rsync command.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

controller/README.md

@@ -4,7 +4,7 @@
 
 A single, lightweight Go container that replaces Portainer + scattered systemd scripts with a unified, Hungarian-language web dashboard for managing Docker Compose stacks, backups, storage, monitoring, and notifications on customer hardware.
 
-**Current version: v0.12.5**
+**Current version: v0.12.6**
 
 ---
 
@@ -196,6 +196,10 @@ Implements the 3-2-1 backup rule by copying data to a different physical drive.
   - External mount: block if <100 MB free; warn/block at 90%/95% usage
   - System drive (same block device as `/`): require ≥10 GB free AND <90% usage to protect OS stability; allowed with a logged warning (no hard block for non-mount-point destinations)
   - Web UI `CheckBackupDestination` matches runner thresholds — no surprise divergence between UI and actual enforcement
+- **Rsync destination layout** (`runRsyncBackup`):
+  - Single mount: data goes directly into `backups/rsync/<app>/` (no extra nesting)
+  - Multiple mounts: each gets a `backups/rsync/<app>/<leaf>/` subfolder named after the mount's base directory; duplicate leaf names disambiguated with `_N` suffix
+  - DB dump files excluded: `--exclude backups/*.sql.gz`, `--exclude backups/*.sql`, `--exclude backups/*.dump` — avoids duplicating data already managed by the pg_dump layer
 - Safety guards: destination ≠ source, path-overlap check, writable check
 - **Chained execution**: cross-drive runs immediately after nightly restic backup (daily apps every night, weekly apps on Sundays) for DB/file consistency
 - Per-app concurrency lock prevents overlapping runs

controller/internal/backup/crossdrive.go

@@ -203,20 +203,22 @@ func (r *CrossDriveRunner) runRsyncBackup(ctx context.Context, stackName, destBa
 		return fmt.Errorf("creating rsync dest dir: %w", err)
 	}
 
-	for _, srcMount := range mounts {
-		// Preserve directory structure: strip the storage path prefix to get relative subpath
-		// e.g., /mnt/hdd_placeholder/storage/immich/ → storage/immich/
-		rel := srcMount
-		// Find the topmost non-root segment of the mount path (after the mount point itself)
-		// Use a simple approach: keep everything from the first significant segment after /mnt/...
-		parts := strings.SplitN(strings.TrimPrefix(srcMount, "/"), "/", 3)
-		if len(parts) >= 3 {
-			rel = parts[2] // e.g., "storage/immich"
+	for i, srcMount := range mounts {
+		var dstPath string
+		if len(mounts) == 1 {
+			// Single mount: rsync directly into the stack folder (no extra nesting)
+			dstPath = destDir
 		} else {
-			rel = filepath.Base(srcMount)
+			// Multiple mounts: use the leaf directory name as subfolder
+			leaf := filepath.Base(srcMount)
+			dstPath = filepath.Join(destDir, leaf)
+			// Disambiguate duplicate leaf names (e.g. two mounts both named "data")
+			if i > 0 {
+				if _, err := os.Stat(dstPath); err == nil {
+					dstPath = filepath.Join(destDir, fmt.Sprintf("%s_%d", leaf, i))
+				}
+			}
 		}
-
-		dstPath := filepath.Join(destDir, rel)
 		if err := os.MkdirAll(dstPath, 0755); err != nil {
 			return fmt.Errorf("creating rsync destination: %w", err)
 		}
@@ -225,7 +227,12 @@ func (r *CrossDriveRunner) runRsyncBackup(ctx context.Context, stackName, destBa
 		src := strings.TrimRight(srcMount, "/") + "/"
 		dst := strings.TrimRight(dstPath, "/") + "/"
 
-		cmd := exec.CommandContext(ctx, "rsync", "-a", "--delete", src, dst)
+		// Exclude app-internal DB dump files — the controller handles DB backups via pg_dump separately.
+		cmd := exec.CommandContext(ctx, "rsync", "-a", "--delete",
+			"--exclude", "backups/*.sql.gz",
+			"--exclude", "backups/*.sql",
+			"--exclude", "backups/*.dump",
+			src, dst)
 		r.logger.Printf("[DEBUG] rsync: %s → %s", src, dst)
 		if out, err := cmd.CombinedOutput(); err != nil {
 			return fmt.Errorf("rsync failed for %s: %v (%s)", srcMount, err, strings.TrimSpace(string(out)))