Use all account-level groups with matching names to workspace-level g…

…roups in case no explicit configuration (#277)

Fixes #272
Fixes #236

src/databricks/labs/ucx/install.py

@@ -187,7 +187,9 @@ def _configure(self):
             warehouse_id = new_warehouse.id
 
         selected_groups = self._question(
-            "Comma-separated list of workspace group names to migrate (empty means all)", default="<ALL>"
+            "Comma-separated list of workspace group names to migrate. If not specified, we'll wse all "
+            "account-level groups with matching names to workspace-level groups.",
+            default="<ALL>",
         )
         backup_group_prefix = self._question("Backup prefix", default="db-temp-")
         log_level = self._question("Log level", default="INFO").upper()

src/databricks/labs/ucx/workspace_access/groups.py

@@ -70,7 +70,7 @@ def _list_workspace_groups(self) -> list[iam.Group]:
 
     def _list_account_groups(self) -> list[iam.Group]:
         # TODO: we should avoid using this method, as it's not documented
-        # unfortunately, there's no other way to consistently get the list of account groups
+        # get account-level groups even if they're not (yet) assigned to a workspace
         logger.debug("Listing account groups...")
         account_groups = [
             iam.Group.from_dict(r)
@@ -160,19 +160,25 @@ def prepare_groups_in_environment(self):
             "Preparing groups in the current environment. At this step we'll verify that all groups "
             "exist and are of the correct type. If some temporary groups are missing, they'll be created"
         )
-        if self.config.selected:
+        group_names = self.config.selected
+        if group_names:
             logger.info("Using the provided group listing")
 
-            for g in self.config.selected:
+            for g in group_names:
                 assert g not in self.SYSTEM_GROUPS, f"Cannot migrate system group {g}"
                 assert self._get_group(g, "workspace"), f"Group {g} not found on the workspace level"
                 assert self._get_group(g, "account"), f"Group {g} not found on the account level"
 
-            self._set_migration_groups(self.config.selected)
-        else:
-            logger.info("No group listing provided, all available workspace-level groups will be used")
-            available_group_names = [g.display_name for g in self._workspace_groups]
-            self._set_migration_groups(groups_names=available_group_names)
+        if not group_names:
+            logger.info(
+                "No group listing provided, all available workspace-level groups that have an account-level "
+                "group with the same name will be used"
+            )
+            ws_group_names = {_.display_name for _ in self._workspace_groups}
+            ac_group_names = {_.display_name for _ in self._account_groups}
+            group_names = list(ws_group_names.intersection(ac_group_names))
+
+        self._set_migration_groups(group_names)
         logger.info("Environment prepared successfully")
 
     @property

tests/integration/workspace_access/test_groups.py

@@ -19,6 +19,27 @@ def test_prepare_environment(ws, make_ucx_group):
         assert _ws_members == _backup_members
 
 
+def test_prepare_environment_no_groups_selected(ws, make_ucx_group, make_group, make_acc_group):
+    make_group()
+    make_acc_group()
+    for_test = [make_ucx_group(), make_ucx_group()]
+
+    group_manager = GroupManager(ws, GroupsConfig(auto=True))
+    group_manager.prepare_groups_in_environment()
+
+    group_migration_state = group_manager.migration_groups_provider
+    for _info in group_migration_state.groups:
+        _ws = ws.groups.get(id=_info.workspace.id)
+        _backup = ws.groups.get(id=_info.backup.id)
+        # https://github.com/databricks/databricks-sdk-py/pull/361 may fix the NPE gotcha with empty members
+        _ws_members = sorted([m.value for m in _ws.members])
+        _backup_members = sorted([m.value for m in _backup.members])
+        assert _ws_members == _backup_members
+
+    for g, _ in for_test:
+        assert group_migration_state.get_by_workspace_group_name(g.display_name) is not None
+
+
 def test_group_listing(ws: WorkspaceClient, make_ucx_group):
     ws_group, acc_group = make_ucx_group()
     manager = GroupManager(ws, GroupsConfig(selected=[ws_group.display_name]))