fix default pvc mounting with kubespawner 7

- remove unneeded default for pvcNameTemplate
- use new `{pvc_name}` template field to mount the spawner's resolved pvc,
      rather than overriding the claim name, which may not match the created pvc

jupyterhub/files/hub/jupyterhub_config.py

@@ -256,7 +256,8 @@ def camelCaseify(s):
 storage_type = get_config("singleuser.storage.type")
 if storage_type == "dynamic":
     pvc_name_template = get_config("singleuser.storage.dynamic.pvcNameTemplate")
-    c.KubeSpawner.pvc_name_template = pvc_name_template
+    if pvc_name_template:
+        c.KubeSpawner.pvc_name_template = pvc_name_template
     volume_name_template = get_config("singleuser.storage.dynamic.volumeNameTemplate")
     c.KubeSpawner.storage_pvc_ensure = True
     set_config_if_not_none(
@@ -275,7 +276,7 @@ def camelCaseify(s):
     c.KubeSpawner.volumes = [
         {
             "name": volume_name_template,
-            "persistentVolumeClaim": {"claimName": pvc_name_template},
+            "persistentVolumeClaim": {"claimName": "{pvc_name}"},
         }
     ]
     c.KubeSpawner.volume_mounts = [

jupyterhub/values.yaml

@@ -413,8 +413,8 @@ singleuser:
     homeMountPath: /home/jovyan
     dynamic:
       storageClass:
-      pvcNameTemplate: claim-{username}{servername}
-      volumeNameTemplate: volume-{username}{servername}
+      pvcNameTemplate:
+      volumeNameTemplate: volume-{user_server}
       storageAccessModes: [ReadWriteOnce]
       subPath:
   image: