- removed unecessary SubordinateBase class

- added based_on_channel class argument

cou/apps/auxiliary_subordinate.py

@@ -14,26 +14,14 @@
 """Auxiliary subordinate application class."""
 from cou.apps.auxiliary import OVN, AuxiliaryApplication
 from cou.apps.factory import AppFactory
-from cou.apps.subordinate import SubordinateBase
-from cou.utils.openstack import AUXILIARY_SUBORDINATES, OpenStackRelease
+from cou.apps.subordinate import SubordinateApplication
+from cou.utils.openstack import AUXILIARY_SUBORDINATES
 
 
 @AppFactory.register_application(AUXILIARY_SUBORDINATES)
-class AuxiliarySubordinateApplication(SubordinateBase, AuxiliaryApplication):
+class AuxiliarySubordinateApplication(SubordinateApplication, AuxiliaryApplication):
     """Auxiliary subordinate application class."""
 
-    @property
-    def current_os_release(self) -> OpenStackRelease:
-        """Infer the OpenStack release from subordinate charm's channel.
-
-        We cannot determine the OpenStack release base on workload packages because the principal
-        charm has already upgraded the packages.
-
-        :return: OpenStackRelease object.
-        :rtype: OpenStackRelease
-        """
-        return self.channel_codename
-
 
 @AppFactory.register_application(["ovn-chassis"])
 class OVNSubordinate(OVN, AuxiliarySubordinateApplication):

cou/apps/base.py

@@ -67,6 +67,9 @@ class OpenStackApplication(Application):
     packages_to_hold: Optional[list] = field(default=None, init=False)
     wait_timeout: int = field(default=STANDARD_IDLE_TIMEOUT, init=False)
     wait_for_model: bool = field(default=False, init=False)  # waiting only for application itself
+    # OpenStack apps rely on the workload version of the packages to evaluate current OpenStack
+    # release
+    based_on_channel = False
 
     def __hash__(self) -> int:
         """Hash magic method for Application.

cou/apps/channel_based.py

@@ -28,6 +28,9 @@
 class ChannelBasedApplication(OpenStackApplication):
     """Application for charms that are channel based."""
 
+    # rely on the channel to evaluate current OpenStack release
+    based_on_channel = True
+
     def get_latest_os_version(self, unit: Unit) -> OpenStackRelease:
         """Get the latest compatible OpenStack release based on the channel.
 

cou/apps/subordinate.py

@@ -25,9 +25,25 @@
 logger = logging.getLogger(__name__)
 
 
-class SubordinateBase(OpenStackApplication):
+@AppFactory.register_application(SUBORDINATES)
+class SubordinateApplication(OpenStackApplication):
     """Subordinate base class."""
 
+    # subordinate apps rely on the channel to evaluate current OpenStack release
+    based_on_channel = True
+
+    @property
+    def current_os_release(self) -> OpenStackRelease:
+        """Infer the OpenStack release from subordinate charm's channel.
+
+        We cannot determine the OpenStack release base on workload packages because the principal
+        charm has already upgraded the packages.
+
+        :return: OpenStackRelease object.
+        :rtype: OpenStackRelease
+        """
+        return self.channel_codename
+
     def _check_application_target(self, target: OpenStackRelease) -> None:
         """Check if the application is already upgraded.
 
@@ -87,20 +103,3 @@ def post_upgrade_steps(
         :rtype: list[PostUpgradeStep]
         """
         return []
-
-
-@AppFactory.register_application(SUBORDINATES)
-class SubordinateApplication(SubordinateBase):
-    """Subordinate application class."""
-
-    @property
-    def current_os_release(self) -> OpenStackRelease:
-        """Infer the OpenStack release from subordinate charm's channel.
-
-        We cannot determine the OpenStack release base on workload packages because the principal
-        charm has already upgraded the packages.
-
-        :return: OpenStackRelease object.
-        :rtype: OpenStackRelease
-        """
-        return self.channel_codename

cou/steps/analyze.py

@@ -20,9 +20,7 @@
 from typing import Optional
 
 from cou.apps.base import OpenStackApplication
-from cou.apps.channel_based import ChannelBasedApplication
 from cou.apps.factory import AppFactory
-from cou.apps.subordinate import SubordinateBase
 from cou.utils import juju_utils
 from cou.utils.app_utils import stringify_objects
 from cou.utils.openstack import DATA_PLANE_CHARMS, UPGRADE_ORDER, OpenStackRelease
@@ -171,10 +169,7 @@ def min_os_release_apps(apps: list[OpenStackApplication]) -> Optional[OpenStackR
         # be considered when on 'latest/stable' or from Charmstore because it's not reliable and
         # will be considered as Ussuri.
         apps_skipped = {
-            app
-            for app in apps
-            if isinstance(app, (ChannelBasedApplication, SubordinateBase))
-            and app.using_non_release_channel
+            app for app in apps if app.based_on_channel and app.using_non_release_channel
         }
         if apps_skipped:
             logger.debug(

cou/steps/plan.py

@@ -35,7 +35,7 @@
 from cou.apps.base import OpenStackApplication
 from cou.apps.channel_based import ChannelBasedApplication  # noqa: F401
 from cou.apps.core import Keystone, Octavia, Swift  # noqa: F401
-from cou.apps.subordinate import SubordinateApplication, SubordinateBase  # noqa: F401
+from cou.apps.subordinate import SubordinateApplication  # noqa: F401
 from cou.commands import CONTROL_PLANE, DATA_PLANE, HYPERVISORS, CLIargs
 from cou.exceptions import (
     COUException,