Add log to inform skipped(non-empty) hypervisors (canonical#351)

Add log to inform user about skipped hypervisors(those having VMs
running) at plan stage.

fixes:
canonical#326

---------

Co-authored-by: Robert Gildein <[email protected]>
Co-authored-by: TQ X <[email protected]>

cou/steps/plan.py

@@ -50,7 +50,7 @@
 from cou.steps.analyze import Analysis
 from cou.steps.backup import backup
 from cou.steps.hypervisor import HypervisorUpgradePlanner
-from cou.utils.app_utils import set_require_osd_release_option
+from cou.utils.app_utils import set_require_osd_release_option, stringify_units
 from cou.utils.juju_utils import DEFAULT_TIMEOUT, Machine, Unit
 from cou.utils.nova_compute import get_empty_hypervisors
 from cou.utils.openstack import LTS_TO_OS_RELEASE, OpenStackRelease
@@ -594,6 +594,7 @@ async def _get_upgradable_hypervisors_machines(
     )
 
     if cli_force:
+        logger.info("Selected all hypervisors: %s", stringify_units(nova_compute_units))
         return nova_compute_machines
 
     return await get_empty_hypervisors(nova_compute_units, analysis_result.model)

cou/utils/app_utils.py

@@ -15,10 +15,10 @@
 """Application utilities."""
 import json
 import logging
-from typing import Optional
+from typing import Iterable, Optional
 
 from cou.exceptions import RunUpgradeError
-from cou.utils.juju_utils import Model
+from cou.utils.juju_utils import Model, Unit
 from cou.utils.openstack import CEPH_RELEASES
 
 logger = logging.getLogger(__name__)
@@ -133,3 +133,15 @@ async def _get_current_osd_release(unit: str, model: Model) -> str:
     logger.debug("Currently OSDs are on the '%s' release", current_osd_release)
 
     return current_osd_release
+
+
+def stringify_units(units: Iterable[Unit]) -> str:
+    """Convert Units into a comma-separated string of unit names, sorted alphabetically.
+
+    :param units: An iterable of Unit objects to be converted.
+    :type units: Iterable[Unit]
+    :return: A comma-separated string of sorted unit names.
+    :rtype: str
+    """
+    sorted_unit_names = sorted([unit.name for unit in units])
+    return ", ".join(sorted_unit_names)

cou/utils/nova_compute.py

@@ -18,6 +18,7 @@
 import logging
 
 from cou.exceptions import HaltUpgradeExecution
+from cou.utils.app_utils import stringify_units
 from cou.utils.juju_utils import Machine, Model, Unit
 
 logger = logging.getLogger(__name__)
@@ -36,7 +37,14 @@ async def get_empty_hypervisors(units: list[Unit], model: Model) -> list[Machine
     tasks = [get_instance_count(unit.name, model) for unit in units]
     instances = await asyncio.gather(*tasks)
     units_instances = zip(units, instances)
-    return [unit.machine for unit, instances in units_instances if instances == 0]
+    empty_units = {unit for unit, instances in units_instances if instances == 0}
+    skipped_units = set(units) - empty_units
+
+    if skipped_units:
+        logger.warning("Found non-empty hypervisors: %s", stringify_units(skipped_units))
+    logger.info("Selected hypervisors: %s", stringify_units(empty_units))
+
+    return [unit.machine for unit in empty_units]
 
 
 async def get_instance_count(unit: str, model: Model) -> int:

tests/unit/utils/test_nova_compute.py

@@ -11,7 +11,6 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
-
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
@@ -64,16 +63,31 @@ async def test_get_instance_count_invalid_result(model, result_key, value):
     ],
 )
 @pytest.mark.asyncio
+@patch("cou.utils.nova_compute.logger")
 @patch("cou.utils.nova_compute.get_instance_count")
 async def test_get_empty_hypervisors(
-    mock_instance_count, hypervisors_count, expected_result, model
+    mock_instance_count, mock_logger, hypervisors_count, expected_result, model
 ):
     mock_instance_count.side_effect = [count for _, count in hypervisors_count]
     result = await nova_compute.get_empty_hypervisors(
         [_mock_nova_unit(nova_unit) for nova_unit, _ in hypervisors_count], model
     )
+
     assert {machine.machine_id for machine in result} == expected_result
 
+    selected_hypervisors = ", ".join(
+        [f"nova-compute/{i}" for i, count in hypervisors_count if count == 0]
+    )
+    non_empty_hypervisors = ", ".join(
+        [f"nova-compute/{i}" for i, count in hypervisors_count if count != 0]
+    )
+
+    mock_logger.info.assert_called_once_with("Selected hypervisors: %s", selected_hypervisors)
+    if non_empty_hypervisors:
+        mock_logger.warning.assert_called_once_with(
+            "Found non-empty hypervisors: %s", non_empty_hypervisors
+        )
+
 
 @pytest.mark.parametrize("instance_count", [1, 10, 50])
 @pytest.mark.asyncio