feat(rwx): share manager pod respects the storageClass.allowedTopologies

In the Longhorn storage system, a share manager pod of a rwx volume is created on a random node.
The purpose of this update is to enhance the locality of an RWX volume and its share manager pod.
It accomplishes this by converting the storageClass.allowedTopologies setting into an affinity
configuration for the share manager pod. As a result, both the pod and the RWX volume respect
this affinity, ensuring their allocation to an optimal node.

Longhorn 7872

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

controller/share_manager_controller.go

@@ -744,6 +744,36 @@ func (c *ShareManagerController) syncShareManagerPod(sm *longhorn.ShareManager)
 	return nil
 }
 
+func (c *ShareManagerController) getAffinityFromStorageClass(sc *storagev1.StorageClass) *corev1.Affinity {
+	var matchLabelExpressions []corev1.NodeSelectorRequirement
+
+	for _, topology := range sc.AllowedTopologies {
+		for _, expression := range topology.MatchLabelExpressions {
+			matchLabelExpressions = append(matchLabelExpressions, corev1.NodeSelectorRequirement{
+				Key:      expression.Key,
+				Operator: corev1.NodeSelectorOpIn,
+				Values:   expression.Values,
+			})
+		}
+	}
+
+	if len(matchLabelExpressions) == 0 {
+		return nil
+	}
+
+	return &corev1.Affinity{
+		NodeAffinity: &corev1.NodeAffinity{
+			RequiredDuringSchedulingIgnoredDuringExecution: &corev1.NodeSelector{
+				NodeSelectorTerms: []corev1.NodeSelectorTerm{
+					{
+						MatchExpressions: matchLabelExpressions,
+					},
+				},
+			},
+		},
+	}
+}
+
 func (c *ShareManagerController) getShareManagerNodeSelectorFromStorageClass(sc *storagev1.StorageClass) map[string]string {
 	value, ok := sc.Parameters["shareManagerNodeSelector"]
 	if !ok {
@@ -815,15 +845,18 @@ func (c *ShareManagerController) createShareManagerPod(sm *longhorn.ShareManager
 		return nil, err
 	}
 
+	var affinity *corev1.Affinity
 	if pv.Spec.StorageClassName != "" {
 		sc, err := c.ds.GetStorageClass(pv.Spec.StorageClassName)
 		if err != nil {
 			c.logger.WithError(err).Warnf("Failed to get storage class %v, will continue the share manager pod creation", pv.Spec.StorageClassName)
 		} else {
+			affinity = c.getAffinityFromStorageClass(sc)
+
+			// Find the node selector from the storage class and merge it with the system managed components node selector
 			if nodeSelector == nil {
 				nodeSelector = map[string]string{}
 			}
-			// Find the node selector from the storage class and merge it with the system managed components node selector
 			nodeSelectorFromStorageClass := c.getShareManagerNodeSelectorFromStorageClass(sc)
 			for k, v := range nodeSelectorFromStorageClass {
 				nodeSelector[k] = v
@@ -855,7 +888,7 @@ func (c *ShareManagerController) createShareManagerPod(sm *longhorn.ShareManager
 			string(secret.Data[csi.CryptoPBKDF]))
 	}
 
-	manifest := c.createPodManifest(sm, annotations, tolerations, imagePullPolicy, nil, registrySecret,
+	manifest := c.createPodManifest(sm, annotations, tolerations, affinity, imagePullPolicy, nil, registrySecret,
 		priorityClass, nodeSelector, fsType, mountOptions, cryptoKey, cryptoParams)
 	pod, err := c.ds.CreatePod(manifest)
 	if err != nil {
@@ -891,7 +924,7 @@ func (c *ShareManagerController) createServiceManifest(sm *longhorn.ShareManager
 }
 
 func (c *ShareManagerController) createPodManifest(sm *longhorn.ShareManager, annotations map[string]string, tolerations []corev1.Toleration,
-	pullPolicy corev1.PullPolicy, resourceReq *corev1.ResourceRequirements, registrySecret, priorityClass string,
+	affinity *corev1.Affinity, pullPolicy corev1.PullPolicy, resourceReq *corev1.ResourceRequirements, registrySecret, priorityClass string,
 	nodeSelector map[string]string, fsType string, mountOptions []string, cryptoKey string, cryptoParams *crypto.EncryptParams) *corev1.Pod {
 
 	// command args for the share-manager
@@ -915,6 +948,7 @@ func (c *ShareManagerController) createPodManifest(sm *longhorn.ShareManager, an
 			OwnerReferences: datastore.GetOwnerReferencesForShareManager(sm, true),
 		},
 		Spec: corev1.PodSpec{
+			Affinity:           affinity,
 			ServiceAccountName: c.serviceAccount,
 			Tolerations:        util.GetDistinctTolerations(tolerations),
 			NodeSelector:       nodeSelector,