CI: Multinode version selector logic & linting

Author: Alex-Welsh

.github/workflows/multinode-inputs.py

@@ -17,7 +17,6 @@ class OSRelease:
 @dataclass
 class OpenStackRelease:
     version: str
-    previous_version: str
     os_releases: t.List[OSRelease]
 
 
@@ -34,11 +33,12 @@ class Scenario:
 UBUNTU_NOBLE = OSRelease("ubuntu", "noble", "ubuntu")
 # NOTE(upgrade): Add supported releases here.
 OPENSTACK_RELEASES = [
-    OpenStackRelease("2023.1", "zed", [ROCKY_9, UBUNTU_JAMMY]),
-    OpenStackRelease("2024.1", "2023.1", [ROCKY_9, UBUNTU_JAMMY]),
-    OpenStackRelease("2025.1", "2024.1", [ROCKY_9, UBUNTU_NOBLE]),
+    OpenStackRelease("2023.1", [ROCKY_9, UBUNTU_JAMMY]),
+    OpenStackRelease("2024.1", [ROCKY_9, UBUNTU_JAMMY]),
+    OpenStackRelease("2025.1", [ROCKY_9, UBUNTU_NOBLE]),
 ]
 NEUTRON_PLUGINS = ["ovs", "ovn"]
+VERSION_HIERARCHY = ["zed", "2023.1", "2024.1", "2025.1"]
 
 
 def main() -> None:
@@ -52,13 +52,17 @@ def random_scenario() -> Scenario:
     openstack_release = random.choice(OPENSTACK_RELEASES)
     os_release = random.choice(openstack_release.os_releases)
     neutron_plugin = random.choice(NEUTRON_PLUGINS)
-    upgrade = 'major' if random.random() > 0.6 else 'none'
+    upgrade = "major" if random.random() > 0.6 else "none"
     return Scenario(openstack_release, os_release, neutron_plugin, upgrade)
 
 
 def generate_inputs(scenario: Scenario) -> t.Dict[str, str]:
     branch = get_branch(scenario.openstack_release.version)
-    previous_branch = get_branch(scenario.openstack_release.previous_version)
+    previous_branch = get_branch(
+        VERSION_HIERARCHY[
+            VERSION_HIERARCHY.index(scenario.openstack_release.version) - 1
+        ]
+    )
     inputs = {
         "os_distribution": scenario.os_release.distribution,
         "os_release": scenario.os_release.release,