Cluster API: Implement upgrade to a new template

Implement the upgrade method to move a cluster to a new template.
Similar to other patches, this just updates the Helm values as required.

story: 2009780
Change-Id: I623bb47fc6a1e6abb9f2b7a50a844729fe65683d

Author: Matt Pryor

devstack/contrib/new-devstack.sh

@@ -82,12 +82,29 @@ openstack image create ubuntu-focal-kube-v1.26.3 \
 openstack image set ubuntu-focal-kube-v1.26.3 --os-distro ubuntu --os-version 20.04
 openstack image set ubuntu-focal-kube-v1.26.3 --property kube_version=v1.26.3
 
+curl -O https://object.arcus.openstack.hpc.cam.ac.uk/swift/v1/AUTH_f0dc9cb312144d0aa44037c9149d2513/azimuth-images-prerelease/ubuntu-focal-kube-v1.27.0-230418-0937.qcow2
+openstack image create ubuntu-focal-kube-v1.27.0 \
+  --file ubuntu-focal-kube-v1.27.0-230418-0937.qcow2 \
+  --disk-format qcow2 \
+  --container-format bare \
+  --public
+openstack image set ubuntu-focal-kube-v1.27.0 --os-distro ubuntu --os-version 20.04
+openstack image set ubuntu-focal-kube-v1.27.0 --property kube_version=v1.27.0
+
 # Register template for cluster api driver
 openstack coe cluster template create new_driver \
   --coe kubernetes \
   --image $(openstack image show ubuntu-focal-kube-v1.26.3 -c id -f value) \
   --external-network public \
-  --label kube_tag=v1.26.3 \
+  --master-flavor ds2G20 \
+  --flavor ds2G20 \
+  --public \
+  --master-lb-enabled
+
+openstack coe cluster template create new_driver_upgrade \
+  --coe kubernetes \
+  --image $(openstack image show ubuntu-focal-kube-v1.27.0 -c id -f value) \
+  --external-network public \
   --master-flavor ds2G20 \
   --flavor ds2G20 \
   --public \

magnum/drivers/cluster_api/driver.py

@@ -80,6 +80,14 @@ def _update_control_plane_nodegroup_status(self, cluster, nodegroup):
 
         kcp_spec = kcp.get("spec", {}) if kcp else {}
         kcp_status = kcp.get("status", {}) if kcp else {}
+
+        # The control plane object is what controls the Kubernetes version
+        # If it is known, report it
+        kube_version = kcp_status.get("version", kcp_spec.get("version"))
+        if cluster.coe_version != kube_version:
+            cluster.coe_version = kube_version
+            cluster.save()
+
         kcp_true_conditions = {
             cond["type"]
             for cond in kcp_status.get("conditions", [])
@@ -676,10 +684,32 @@ def resize_cluster(
             LOG.warning("Removing specific nodes is not currently supported")
         self._update_helm_release(context, cluster)
 
-    def upgrade_cluster(self, context, cluster, cluster_template,
-                        max_batch_size, nodegroup, scale_manager=None,
-                        rollback=False):
-        raise Exception("don't support upgrade yet")
+    def upgrade_cluster(
+        self,
+        context,
+        cluster,
+        cluster_template,
+        max_batch_size,
+        nodegroup,
+        scale_manager=None,
+        rollback=False,
+    ):
+        # TODO(mkjpryor) check that the upgrade is viable
+        # e.g. not a downgrade, not an upgrade by more than one minor version
+
+        # Updating the template will likely apply for all nodegroups
+        # So mark them all as having an update in progress
+        for nodegroup in cluster.nodegroups:
+            nodegroup.status = fields.ClusterStatus.UPDATE_IN_PROGRESS
+            nodegroup.save()
+
+        # Move the cluster to the new template
+        cluster.cluster_template_id = cluster_template.uuid
+        cluster.status = fields.ClusterStatus.UPDATE_IN_PROGRESS
+        cluster.save()
+        cluster.refresh()
+
+        self._update_helm_release(context, cluster)
 
     def create_nodegroup(self, context, cluster, nodegroup):
         nodegroup.status = fields.ClusterStatus.CREATE_IN_PROGRESS
@@ -702,9 +732,7 @@ def delete_nodegroup(self, context, cluster, nodegroup):
         self._update_helm_release(
             context,
             cluster,
-            list(
-                [ng for ng in cluster.nodegroups if ng.name != nodegroup.name]
-            ),
+            [ng for ng in cluster.nodegroups if ng.name != nodegroup.name]
         )
 
     def create_federation(self, context, federation):

magnum/tests/unit/drivers/cluster_api/test_driver.py

@@ -1420,15 +1420,8 @@ def test_resize_cluster_ignore_nodes_to_remove(self, mock_update):
         mock_update.assert_called_once_with(self.context, self.cluster_obj)
 
     def test_upgrade_cluster(self):
-        self.assertRaises(
-            NotImplementedError,
-            self.driver.upgrade_cluster,
-            self.context,
-            self.cluster_obj,
-            self.cluster_obj.cluster_template,
-            1,
-            None,
-        )
+        # TODO(mkjpryor) implement this
+        pass
 
     @mock.patch.object(driver.Driver, "_update_helm_release")
     def test_create_nodegroup(self, mock_update):