fix(backup): match the engine on the image name

has_image tested the pattern against the raw .Config.Image, so anything in the reference could decide which dump tool runs -- including the registry host and the tag. A swarm node that hosts the local registry prefixes every pull with its own name, and that node is named after the app under test, so a Postgres container reads as svc-db-mariadb-swarm-mgr-01:5000/postgres_custom:17-3.5. dumps.py tries mariadb before postgres, matched on the hostname, and dumped Postgres with mariadb-dump: exit 127, the image does not ship it. The BackupException took the backup unit down with it.

image_name strips digest, tag and registry host and matches on the repository path, so the decision rests on the image alone. Same intent as the exact --images-* matching from f9776ac, applied to the one place that commit did not reach. Tags stop deciding too: xwiki_custom:lts-postgres-tomcat no longer reads as Postgres.

The e2e reproduces the shape without a registry -- a docker tag is enough for .Config.Image to carry the reference verbatim -- and asserts a real pg_dump lands. Under the old code mariadb-dump aborts and no dump file exists.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/unit/backup/test_docker_image_name.py

@@ -0,0 +1,50 @@
+import unittest
+from unittest.mock import patch
+
+from baudolo.backup import docker as docker_mod
+
+
+def _with_image(reference: str):
+    return patch.object(docker_mod, "execute_shell_command", return_value=[reference])
+
+
+class TestImageName(unittest.TestCase):
+    def test_plain_reference(self) -> None:
+        with _with_image("postgres:16"):
+            self.assertEqual(docker_mod.image_name("c1"), "postgres")
+
+    def test_registry_host_is_dropped(self) -> None:
+        with _with_image("svc-db-mariadb-swarm-mgr-01:5000/postgres_custom:17-3.5"):
+            self.assertEqual(docker_mod.image_name("c1"), "postgres_custom")
+
+    def test_pull_through_path_is_kept(self) -> None:
+        with _with_image(
+            "svc-db-mariadb-swarm-mgr-01:5000/ghcr.io/x/mirror/docker.io/postgres:16"
+        ):
+            self.assertEqual(
+                docker_mod.image_name("c1"), "ghcr.io/x/mirror/docker.io/postgres"
+            )
+
+    def test_digest_is_dropped(self) -> None:
+        with _with_image("registry:5000/postgres@sha256:" + "0" * 64):
+            self.assertEqual(docker_mod.image_name("c1"), "postgres")
+
+
+class TestHasImage(unittest.TestCase):
+    def test_registry_hostname_does_not_decide_the_engine(self) -> None:
+        with _with_image("svc-db-mariadb-swarm-mgr-01:5000/postgres_custom:17-3.5"):
+            self.assertFalse(docker_mod.has_image("c1", "mariadb"))
+        with _with_image("svc-db-mariadb-swarm-mgr-01:5000/postgres_custom:17-3.5"):
+            self.assertTrue(docker_mod.has_image("c1", "postgres"))
+
+    def test_tag_does_not_decide_the_engine(self) -> None:
+        with _with_image("registry:5000/xwiki_custom:lts-postgres-tomcat"):
+            self.assertFalse(docker_mod.has_image("c1", "postgres"))
+
+    def test_mirrored_mariadb_still_matches(self) -> None:
+        with _with_image("registry:5000/ghcr.io/x/mirror/docker.io/mariadb:11"):
+            self.assertTrue(docker_mod.has_image("c1", "mariadb"))
+
+
+if __name__ == "__main__":
+    unittest.main()