Remove the option to revert to overlay2 driver (#6399)

OS Agent will no longer support migrating to the overlay2 driver due to reasons
explained in home-assistant/os-agent#245. Remove it from the Docker API as
well.

supervisor/api/docker.py

@@ -46,7 +46,7 @@ SCHEMA_OPTIONS = vol.Schema(
 
 SCHEMA_MIGRATE_DOCKER_STORAGE_DRIVER = vol.Schema(
     {
-        vol.Required(ATTR_STORAGE_DRIVER): vol.In(["overlayfs", "overlay2"]),
+        vol.Required(ATTR_STORAGE_DRIVER): vol.In(["overlayfs"]),
     }
 )
 

tests/api/test_docker.py

@@ -118,15 +118,6 @@ async def test_api_migrate_docker_storage_driver(
         in coresys.resolution.suggestions
     )
 
-    # Test migration back to overlay2 (graph driver)
-    system_service.MigrateDockerStorageDriver.calls.clear()
-    resp = await api_client.post(
-        "/docker/migrate-storage-driver",
-        json={"storage_driver": "overlay2"},
-    )
-    assert resp.status == 200
-    assert system_service.MigrateDockerStorageDriver.calls == [("overlay2",)]
-
 
 @pytest.mark.parametrize("os_available", ["17.0.rc1"], indirect=True)
 async def test_api_migrate_docker_storage_driver_invalid_backend(

tests/dbus_service_mocks/agent_system.py

@@ -35,8 +35,8 @@ class System(DBusServiceMock):
         """Migrate Docker storage driver."""
         if isinstance(self.response_migrate_docker_storage_driver, DBusError):
             raise self.response_migrate_docker_storage_driver  # pylint: disable=raising-bad-type
-        if backend not in ("overlayfs", "overlay2"):
+        if backend != "overlayfs":
             raise DBusError(
                 ErrorType.FAILED,
-                f"unsupported driver: {backend} (only 'overlayfs' and 'overlay2' are supported)",
+                f"unsupported driver: {backend} (only 'overlayfs' is currently supported)",
             )