added multiple_channels flag to support corner case when rabbitmq

or hacluster that supports more than one channel for an Openstack
release.

cou/apps/auxiliary.py

@@ -179,6 +179,9 @@ class RabbitMQServer(AuxiliaryApplication):
 
     wait_timeout = LONG_IDLE_TIMEOUT
     wait_for_model = True
+    # rabbitmq-server can use channels 3.8 or 3.9 on focal.
+    # COU changes to 3.9 if the channel is set to 3.8
+    multiple_channels = True
 
 
 @AppFactory.register_application(["ceph-mon"])

cou/apps/auxiliary_subordinate.py

@@ -15,10 +15,9 @@
 from cou.apps.auxiliary import OVN, AuxiliaryApplication
 from cou.apps.factory import AppFactory
 from cou.apps.subordinate import SubordinateApplication
-from cou.utils.openstack import AUXILIARY_SUBORDINATES
 
 
-@AppFactory.register_application(AUXILIARY_SUBORDINATES)
+@AppFactory.register_application(["mysql-router", "ceph-dashboard"])
 class AuxiliarySubordinateApplication(SubordinateApplication, AuxiliaryApplication):
     """Auxiliary subordinate application class."""
 
@@ -33,3 +32,12 @@ def _check_ovn_support(self) -> None:
         :raises ApplicationError: When workload version is lower than 22.03.0.
         """
         OVNSubordinate._validate_ovn_support(self.workload_version)
+
+
+@AppFactory.register_application(["hacluster"])
+class HACluster(AuxiliarySubordinateApplication):
+    """HACluster application class."""
+
+    # hacluster can use channels 2.0.3 or 2.4 on focal.
+    # COU changes to 2.4 if the channel is set to 2.0.3
+    multiple_channels = True

cou/apps/base.py

@@ -71,6 +71,9 @@ class OpenStackApplication(Application):
     # OpenStack apps rely on the workload version of the packages to evaluate current OpenStack
     # release
     based_on_channel = False
+    # multiple_channels set to False means that the charm supports only one channel for
+    # an OpenStack release
+    multiple_channels = False
 
     def __hash__(self) -> int:
         """Hash magic method for Application.
@@ -663,7 +666,7 @@ def _get_upgrade_charm_step(self, target: OpenStackRelease) -> UpgradeStep:
         # Normally, prior the upgrade the channel is equal to the application release.
         # However, when colocated with other app, the channel can be in a release lesser than the
         # workload version of the application.
-        if self.channel_o7k_release <= self.o7k_release:
+        if self.channel_o7k_release <= self.o7k_release or self.multiple_channels:
             return UpgradeStep(
                 description=f"Upgrade '{self.name}' from '{channel}' to the new channel: "
                 f"'{self.target_channel(target)}'",

cou/steps/plan.py

@@ -30,6 +30,7 @@
 )
 from cou.apps.auxiliary_subordinate import (  # noqa: F401
     AuxiliarySubordinateApplication,
+    HACluster,
     OVNSubordinate,
 )
 from cou.apps.base import OpenStackApplication

tests/unit/apps/test_auxiliary_subordinate.py

@@ -17,6 +17,7 @@
 
 from cou.apps.auxiliary_subordinate import (
     AuxiliarySubordinateApplication,
+    HACluster,
     OVNSubordinate,
 )
 from cou.exceptions import ApplicationError, HaltUpgradePlanGeneration
@@ -373,3 +374,33 @@ def test_auxiliary_subordinate_channel_o7k_release_raise(model):
 
     with pytest.raises(ApplicationError, match=exp_msg):
         app.o7k_release
+
+
+def test_hacluster_change_channel(model):
+    """Test that HACluster changes the channel to 2.4 when 2.0.3 is set."""
+    target = OpenStackRelease("victoria")
+    app = HACluster(
+        name="keystone-hacluster",
+        can_upgrade_to="ch:hacluster",
+        charm="hacluster",
+        channel="2.0.3/stable",
+        config={},
+        machines={"0": generate_cou_machine("0", "az-0")},
+        model=model,
+        origin="ch",
+        series="focal",
+        subordinate_to=["keystone"],
+        units={},
+        workload_version="2.0.3",
+    )
+
+    exp_plan = dedent_plan(
+        """\
+    Upgrade plan for 'keystone-hacluster' to 'victoria'
+        Refresh 'keystone-hacluster' to the latest revision of '2.0.3/stable'
+        Upgrade 'keystone-hacluster' from '2.0.3/stable' to the new channel: '2.4/stable'
+        """
+    )
+
+    plan = app.generate_upgrade_plan(target, force=False)
+    assert str(plan) == exp_plan