fix(restore): allow restoring files from different source volume

The file restore command previously assumed that the target volume name
was identical to the volume name used in the backup path. This caused
restores to fail (exit code 2) when restoring data from one volume backup
into a different target volume.

Introduce an optional --source-volume argument for `baudolo-restore files`
to explicitly specify the backup source volume while keeping the target
volume unchanged.

- Default behavior remains fully backward-compatible
- Enables restoring backups from volume A into volume B
- Fixes E2E test scenario restoring into a new volume

Tests:
- Update E2E file restore test to use --source-volume

https://chatgpt.com/share/694ec70f-1d7c-800f-b221-9d22e4b0775e

src/baudolo/restore/__main__.py

@@ -10,7 +10,7 @@ from .db.mariadb import restore_mariadb_sql
 
 
 def _add_common_backup_args(p: argparse.ArgumentParser) -> None:
-    p.add_argument("volume_name", help="Docker volume name")
+    p.add_argument("volume_name", help="Docker volume name (target volume)")
     p.add_argument("backup_hash", help="Hashed machine id")
     p.add_argument("version", help="Backup version directory name")
 
@@ -33,10 +33,28 @@ def main(argv: list[str] | None = None) -> int:
     )
     sub = parser.add_subparsers(dest="cmd", required=True)
 
+    # ------------------------------------------------------------------
+    # files
+    # ------------------------------------------------------------------
     p_files = sub.add_parser("files", help="Restore files into a docker volume")
     _add_common_backup_args(p_files)
-    p_files.add_argument("--rsync-image", default="ghcr.io/kevinveenbirkenbach/alpine-rsync")
+    p_files.add_argument(
+        "--rsync-image",
+        default="ghcr.io/kevinveenbirkenbach/alpine-rsync",
+    )
+    p_files.add_argument(
+        "--source-volume",
+        default=None,
+        help=(
+            "Volume name used as backup source path key. "
+            "Defaults to <volume_name> (target volume). "
+            "Use this when restoring from one volume backup into a different target volume."
+        ),
+    )
 
+    # ------------------------------------------------------------------
+    # postgres
+    # ------------------------------------------------------------------
     p_pg = sub.add_parser("postgres", help="Restore a single PostgreSQL database dump")
     _add_common_backup_args(p_pg)
     p_pg.add_argument("--container", required=True)
@@ -45,6 +63,9 @@ def main(argv: list[str] | None = None) -> int:
     p_pg.add_argument("--db-password", required=True)
     p_pg.add_argument("--empty", action="store_true")
 
+    # ------------------------------------------------------------------
+    # mariadb
+    # ------------------------------------------------------------------
     p_mdb = sub.add_parser("mariadb", help="Restore a single MariaDB/MySQL-compatible dump")
     _add_common_backup_args(p_mdb)
     p_mdb.add_argument("--container", required=True)
@@ -55,17 +76,25 @@ def main(argv: list[str] | None = None) -> int:
 
     args = parser.parse_args(argv)
 
-    bp = BackupPaths(
-        args.volume_name,
-        args.backup_hash,
-        args.version,
-        repo_name=args.repo_name,
-        backups_dir=args.backups_dir,
-    )
-
     try:
         if args.cmd == "files":
-            return restore_volume_files(args.volume_name, bp.files_dir(), rsync_image=args.rsync_image)
+            # target volume = args.volume_name
+            # source volume (backup key) defaults to target volume
+            source_volume = args.source_volume or args.volume_name
+
+            bp_files = BackupPaths(
+                source_volume,
+                args.backup_hash,
+                args.version,
+                repo_name=args.repo_name,
+                backups_dir=args.backups_dir,
+            )
+
+            return restore_volume_files(
+                args.volume_name,
+                bp_files.files_dir(),
+                rsync_image=args.rsync_image,
+            )
 
         if args.cmd == "postgres":
             user = args.db_user or args.db_name
@@ -74,7 +103,13 @@ def main(argv: list[str] | None = None) -> int:
                 db_name=args.db_name,
                 user=user,
                 password=args.db_password,
-                sql_path=bp.sql_file(args.db_name),
+                sql_path=BackupPaths(
+                    args.volume_name,
+                    args.backup_hash,
+                    args.version,
+                    repo_name=args.repo_name,
+                    backups_dir=args.backups_dir,
+                ).sql_file(args.db_name),
                 empty=args.empty,
             )
             return 0
@@ -86,7 +121,13 @@ def main(argv: list[str] | None = None) -> int:
                 db_name=args.db_name,
                 user=user,
                 password=args.db_password,
-                sql_path=bp.sql_file(args.db_name),
+                sql_path=BackupPaths(
+                    args.volume_name,
+                    args.backup_hash,
+                    args.version,
+                    repo_name=args.repo_name,
+                    backups_dir=args.backups_dir,
+                ).sql_file(args.db_name),
                 empty=args.empty,
             )
             return 0