feat(rwx): share manager pod respect the newly introduced storageClas…

…s.Parameters["shareManagerNodeSelector"]

The commit introduces an enhancement for specifying the locality of a Read-Write-Many (RWX)
volume and its associated Share Manager Pod within the Longhorn storage system. Previously,
an RWX volume and its Share Manager Pod were created randomly on any node within the Longhorn
cluster, without the ability for users to specify a preferred locality.

Longhorn 7872

Signed-off-by: Derek Su <derek.su@suse.com>

controller/share_manager_controller.go

@@ -743,16 +743,45 @@ func (c *ShareManagerController) syncShareManagerPod(sm *longhorn.ShareManager)
 	return nil
 }
 
+func (c *ShareManagerController) getShareManagerNodeSelectorFromStorageClass(pv *corev1.PersistentVolume) map[string]string {
+	if pv.Spec.StorageClassName == "" {
+		return map[string]string{}
+	}
+
+	sc, err := c.ds.GetStorageClass(pv.Spec.StorageClassName)
+	if err != nil {
+		c.logger.WithError(err).Warnf("Failed to get storage class %v", pv.Spec.StorageClassName)
+		return map[string]string{}
+	}
+
+	value, ok := sc.Parameters["shareManagerNodeSelector"]
+	if !ok {
+		return map[string]string{}
+	}
+
+	nodeSelector, err := types.UnmarshalNodeSelector(value)
+	if err != nil {
+		c.logger.WithError(err).Warnf("Failed to unmarshal node selector %v", value)
+		return map[string]string{}
+	}
+
+	return nodeSelector
+}
+
 // createShareManagerPod ensures existence of service, it's assumed that the pvc for this share manager already exists
 func (c *ShareManagerController) createShareManagerPod(sm *longhorn.ShareManager) (*corev1.Pod, error) {
 	tolerations, err := c.ds.GetSettingTaintToleration()
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to get taint toleration setting before creating share manager pod")
 	}
+
 	nodeSelector, err := c.ds.GetSettingSystemManagedComponentsNodeSelector()
 	if err != nil {
 		return nil, errors.Wrap(err, "failed to get node selector setting before creating share manager pod")
 	}
+	if nodeSelector == nil {
+		nodeSelector = map[string]string{}
+	}
 
 	tolerationsByte, err := json.Marshal(tolerations)
 	if err != nil {
@@ -798,6 +827,12 @@ func (c *ShareManagerController) createShareManagerPod(sm *longhorn.ShareManager
 		return nil, err
 	}
 
+	// Find the node selector from the storage class and merge it with the system managed components node selector
+	nodeSelectorFromStorageClass := c.getShareManagerNodeSelectorFromStorageClass(pv)
+	for k, v := range nodeSelectorFromStorageClass {
+		nodeSelector[k] = v
+	}
+
 	fsType := pv.Spec.CSI.FSType
 	mountOptions := pv.Spec.MountOptions