Fix Hypervisor Upgrade

- HypervisorUpgradePlan was wrongly running steps on parallel which
  caused to change openstack-origin or source at the same time of
  action-managed-upgrade. This could wrongly trigger the upgrade
  on all units.
- added the Psi (Ψ) to user vizualize which steps are going to run
  on parallel
- updated docs

cou/steps/__init__.py

@@ -131,11 +131,19 @@ def __str__(self) -> str:
         """
         result = ""
         tab = "\t"
-        steps_to_visit = [(self, 0)]
+        parallel_char = "Ψ "
+        steps_to_visit = [(self, 0, 0)]
         while steps_to_visit:
-            step, indent = steps_to_visit.pop()
-            result += f"{tab * indent}{step.description}{os.linesep}" if step else ""
-            steps_to_visit.extend([(s, indent + 1) for s in reversed(step.sub_steps)])
+            step, indent, parallel = steps_to_visit.pop()
+            result += (
+                f"{tab * indent}{parallel_char if parallel else ''}{step.description}{os.linesep}"
+                if step
+                else ""
+            )
+            steps_to_visit.extend(
+                [(s, indent + 1, step.parallel) for s in reversed(step.sub_steps)]
+            )
+            # breakpoint()
 
         return result
 
@@ -337,8 +345,8 @@ class ApplicationUpgradePlan(UpgradePlan):
 class HypervisorUpgradePlan(BaseStep):
     """Represents the plan for hypervisor upgrade.
 
-    This class is intended to be used as a group for unit-level upgrade steps, which are
-    grouped by a single hypervisor. It doesn't accept coroutine or parallel as inputs.
+    This class is intended to be used as a group by AZs. It doesn't accept coroutine or parallel
+    as inputs.
 
     All sub-steps will run in parallel.
     """
@@ -351,7 +359,7 @@ def __init__(self, description: str):
         :param description: Description of the step.
         :type description: str
         """
-        super().__init__(description=description, parallel=True, coro=None)
+        super().__init__(description=description, parallel=False, coro=None)
 
 
 class UpgradeStep(BaseStep):

docs/explanation/planning.rst

@@ -33,11 +33,15 @@ The plan has a tree structure with six main sections:
                 availability zone 1
                     pre-upgrade steps
                     upgrade steps
-                        unit 1
-                            unit upgrade steps
+                        Ψ unit 1
+                            unit upgrade step A
+                            ...
+                            unit upgrade step Z
                         ...
-                        unit K
-                            unit upgrade steps
+                        Ψ unit K
+                            unit upgrade step A
+                            ...
+                            unit upgrade step Z
                     post-upgrade steps
                 ...
                 availability zone N
@@ -55,7 +59,7 @@ The plan has a tree structure with six main sections:
 
 The above demonstrates a complete cloud upgrade plan. However, it's also possible to
 target a specific subset of the cloud. For more information, please refer to
-:doc:`Upgrade Groups <./upgrade-groups>`. 
+:doc:`Upgrade Groups <./upgrade-groups>`.
 
 The **pre-upgrade** steps prepare COU for the upgrade process, which includes
 verifying the states or configurations of the applications, units, or of the
@@ -69,5 +73,9 @@ successfully.
 The plan can also be obtained without the need to perform a cloud upgrade using
 the **plan** command. See :doc:`Plan an upgrade <../how-to/plan-upgrade>`.
 
+The Greek letter Psi `Ψ` means that the step will run in parallel compared with other steps in the
+same level. In the example above on the `data-plane hypervisors upgrade`, `unit 1` will run on
+parallel compared with `unit K`, but their `upgrade steps A to Z` will run sequentially.
+
 Different upgrade strategies are chosen for control-plane and data-plane applications
-when preparing the plan. For details, please refer to :doc:`Upgrade <./upgrade>`.
+when preparing the plan. For details, please refer to :doc:`Upgrade <./upgrade>`.

docs/reference/known-issues.rst

@@ -5,6 +5,6 @@ Known issues
 Potential known upgrade bugs and non-standard procedures are listed in the OpenStack Charm Guide:
 
 - `Issues, charm procedures, and OpenStack upgrade notes`_
- 
+
 .. LINKS:
-.. _Issues, charm procedures, and OpenStack upgrade notes: https://docs.openstack.org/charm-guide/latest/project/issues-and-procedures.html
+.. _Issues, charm procedures, and OpenStack upgrade notes: https://docs.openstack.org/charm-guide/latest/project/issues-and-procedures.html

tests/mocked_plans/sample_plans/base.yaml

@@ -5,7 +5,7 @@ plan: |
         Control Plane principal(s) upgrade plan
             Upgrade plan for 'keystone' to 'victoria'
                 Upgrade software packages of 'keystone' from the current APT repositories
-                    Upgrade software packages on unit 'keystone/0'
+                    Ψ Upgrade software packages on unit 'keystone/0'
                 Refresh 'keystone' to the latest revision of 'ussuri/stable'
                 Change charm config of 'keystone' 'action-managed-upgrade' to 'False'
                 Upgrade 'keystone' to the new channel: 'victoria/stable'
@@ -20,13 +20,13 @@ plan: |
             Upgrade plan for 'az-0' to 'victoria'
                 Disable nova-compute scheduler from unit: 'nova-compute/0'
                 Upgrade software packages of 'nova-compute' from the current APT repositories
-                    Upgrade software packages on unit 'nova-compute/0'
+                    Ψ Upgrade software packages on unit 'nova-compute/0'
                 Refresh 'nova-compute' to the latest revision of 'ussuri/stable'
                 Change charm config of 'nova-compute' 'action-managed-upgrade' to 'True'
                 Upgrade 'nova-compute' to the new channel: 'victoria/stable'
                 Change charm config of 'nova-compute' 'source' to 'cloud:focal-victoria'
                 Upgrade plan for units: nova-compute/0
-                    Upgrade plan for unit 'nova-compute/0'
+                    Ψ Upgrade plan for unit 'nova-compute/0'
                         Verify that unit 'nova-compute/0' has no VMs running
                         ├── Pause the unit: 'nova-compute/0'
                         ├── Upgrade the unit: 'nova-compute/0'
@@ -38,7 +38,7 @@ plan: |
             Upgrade plan for 'ceph-osd' to 'victoria'
                 Verify that all 'nova-compute' units has been upgraded
                 Upgrade software packages of 'ceph-osd' from the current APT repositories
-                    Upgrade software packages on unit 'ceph-osd/0'
+                    Ψ Upgrade software packages on unit 'ceph-osd/0'
                 Refresh 'ceph-osd' to the latest revision of 'octopus/stable'
                 Change charm config of 'ceph-osd' 'source' to 'cloud:focal-victoria'
                 Wait for up to 300s for app 'ceph-osd' to reach the idle state

tests/unit/apps/test_auxiliary.py

@@ -1340,9 +1340,9 @@ def test_ceph_osd_upgrade_plan(model):
     Upgrade plan for 'ceph-osd' to 'victoria'
         Verify that all 'nova-compute' units has been upgraded
         Upgrade software packages of 'ceph-osd' from the current APT repositories
-            Upgrade software packages on unit 'ceph-osd/0'
-            Upgrade software packages on unit 'ceph-osd/1'
-            Upgrade software packages on unit 'ceph-osd/2'
+            Ψ Upgrade software packages on unit 'ceph-osd/0'
+            Ψ Upgrade software packages on unit 'ceph-osd/1'
+            Ψ Upgrade software packages on unit 'ceph-osd/2'
         Refresh 'ceph-osd' to the latest revision of 'octopus/stable'
         Change charm config of 'ceph-osd' 'source' to 'cloud:focal-victoria'
         Wait for up to 300s for app 'ceph-osd' to reach the idle state

tests/unit/apps/test_core.py

@@ -783,25 +783,25 @@ def test_nova_compute_upgrade_plan(model):
         Disable nova-compute scheduler from unit: 'nova-compute/1'
         Disable nova-compute scheduler from unit: 'nova-compute/2'
         Upgrade software packages of 'nova-compute' from the current APT repositories
-            Upgrade software packages on unit 'nova-compute/0'
-            Upgrade software packages on unit 'nova-compute/1'
-            Upgrade software packages on unit 'nova-compute/2'
+            Ψ Upgrade software packages on unit 'nova-compute/0'
+            Ψ Upgrade software packages on unit 'nova-compute/1'
+            Ψ Upgrade software packages on unit 'nova-compute/2'
         Refresh 'nova-compute' to the latest revision of 'ussuri/stable'
         Change charm config of 'nova-compute' 'action-managed-upgrade' to 'True'
         Upgrade 'nova-compute' to the new channel: 'victoria/stable'
         Change charm config of 'nova-compute' 'source' to 'cloud:focal-victoria'
         Upgrade plan for units: nova-compute/0, nova-compute/1, nova-compute/2
-            Upgrade plan for unit 'nova-compute/0'
+            Ψ Upgrade plan for unit 'nova-compute/0'
                 Verify that unit 'nova-compute/0' has no VMs running
                 ├── Pause the unit: 'nova-compute/0'
                 ├── Upgrade the unit: 'nova-compute/0'
                 ├── Resume the unit: 'nova-compute/0'
-            Upgrade plan for unit 'nova-compute/1'
+            Ψ Upgrade plan for unit 'nova-compute/1'
                 Verify that unit 'nova-compute/1' has no VMs running
                 ├── Pause the unit: 'nova-compute/1'
                 ├── Upgrade the unit: 'nova-compute/1'
                 ├── Resume the unit: 'nova-compute/1'
-            Upgrade plan for unit 'nova-compute/2'
+            Ψ Upgrade plan for unit 'nova-compute/2'
                 Verify that unit 'nova-compute/2' has no VMs running
                 ├── Pause the unit: 'nova-compute/2'
                 ├── Upgrade the unit: 'nova-compute/2'
@@ -850,13 +850,13 @@ def test_nova_compute_upgrade_plan_single_unit(model):
     Upgrade plan for 'nova-compute' to 'victoria'
         Disable nova-compute scheduler from unit: 'nova-compute/0'
         Upgrade software packages of 'nova-compute' from the current APT repositories
-            Upgrade software packages on unit 'nova-compute/0'
+            Ψ Upgrade software packages on unit 'nova-compute/0'
         Refresh 'nova-compute' to the latest revision of 'ussuri/stable'
         Change charm config of 'nova-compute' 'action-managed-upgrade' to 'True'
         Upgrade 'nova-compute' to the new channel: 'victoria/stable'
         Change charm config of 'nova-compute' 'source' to 'cloud:focal-victoria'
         Upgrade plan for units: nova-compute/0
-            Upgrade plan for unit 'nova-compute/0'
+            Ψ Upgrade plan for unit 'nova-compute/0'
                 Verify that unit 'nova-compute/0' has no VMs running
                 ├── Pause the unit: 'nova-compute/0'
                 ├── Upgrade the unit: 'nova-compute/0'
@@ -902,9 +902,9 @@ def test_cinder_upgrade_plan(model):
         """\
     Upgrade plan for 'cinder' to 'victoria'
         Upgrade software packages of 'cinder' from the current APT repositories
-            Upgrade software packages on unit 'cinder/0'
-            Upgrade software packages on unit 'cinder/1'
-            Upgrade software packages on unit 'cinder/2'
+            Ψ Upgrade software packages on unit 'cinder/0'
+            Ψ Upgrade software packages on unit 'cinder/1'
+            Ψ Upgrade software packages on unit 'cinder/2'
         Refresh 'cinder' to the latest revision of 'ussuri/stable'
         Upgrade 'cinder' to the new channel: 'victoria/stable'
         Change charm config of 'cinder' 'openstack-origin' to 'cloud:focal-victoria'
@@ -952,13 +952,13 @@ def test_cinder_upgrade_plan_single_unit(model):
         """\
     Upgrade plan for 'cinder' to 'victoria'
         Upgrade software packages of 'cinder' from the current APT repositories
-            Upgrade software packages on unit 'cinder/0'
+            Ψ Upgrade software packages on unit 'cinder/0'
         Refresh 'cinder' to the latest revision of 'ussuri/stable'
         Change charm config of 'cinder' 'action-managed-upgrade' to 'True'
         Upgrade 'cinder' to the new channel: 'victoria/stable'
         Change charm config of 'cinder' 'openstack-origin' to 'cloud:focal-victoria'
         Upgrade plan for units: cinder/0
-            Upgrade plan for unit 'cinder/0'
+            Ψ Upgrade plan for unit 'cinder/0'
                 Pause the unit: 'cinder/0'
                 Upgrade the unit: 'cinder/0'
                 Resume the unit: 'cinder/0'

tests/unit/steps/test_execute.py

@@ -449,23 +449,23 @@ async def test_plan_structure(self):
             """
         test plan
             parallel
-                parallel.0
+                Ψ parallel.0
                     parallel.0.0
                     parallel.0.1
                     parallel.0.2
-                parallel.1
+                Ψ parallel.1
                     parallel.1.0
                     parallel.1.1
                     parallel.1.2
-                parallel.2
+                Ψ parallel.2
                     parallel.2.0
                     parallel.2.1
                     parallel.2.2
-                parallel.3
+                Ψ parallel.3
                     parallel.3.0
                     parallel.3.1
                     parallel.3.2
-                parallel.4
+                Ψ parallel.4
                     parallel.4.0
                     parallel.4.1
                     parallel.4.2