mgr/dashboard: adapt nfs export code to the new changes in nfs module

when you create/edit an nfs export from dashboard it leaves this traceback and error

```
Feb 09 14:15:54 ceph-node-00 ceph-mgr[3235]: [dashboard ERROR taskexec] Error while calling Task(ns=nfs/create, md={'path': 'e2e.nfs.bucket', 'fsal': 'RGW', 'cluster_id': 'testnfs'})
                                             Traceback (most recent call last):
                                               File "/usr/share/ceph/mgr/dashboard/tools.py", line 550, in _run
                                                 val = self.task.fn(*self.task.fn_args, **self.task.fn_kwargs)  # type: ignore
                                               File "/usr/share/ceph/mgr/dashboard/controllers/nfs.py", line 148, in create
                                                 ret, _, err = export_mgr.apply_export(cluster_id, json.dumps(raw_ex))
                                             TypeError: 'AppliedExportResults' object is not iterable
Feb 09 14:15:54 ceph-node-00 ceph-mgr[3235]: [dashboard INFO taskmgr] finished Task(ns=nfs/create, md={'path': 'e2e.nfs.bucket', 'fsal': 'RGW', 'cluster_id': 'testnfs'})
Feb 09 14:15:54 ceph-node-00 ceph-mgr[3235]: [dashboard INFO request] [::ffff:192.168.100.1:43896] [POST] [500] [0.767s] [admin] [172.0B] /api/nfs-ganesha/export
```
This started after ceph#46209, so dashboard code needs to be adapted

Fixes: https://tracker.ceph.com/issues/58681
Signed-off-by: Nizamudeen A <[email protected]>

src/pybind/mgr/dashboard/controllers/nfs.py

@@ -145,11 +145,11 @@ def create(self, path, cluster_id, pseudo, access_type,
             'fsal': fsal,
             'clients': clients
         }
-        ret, _, err = export_mgr.apply_export(cluster_id, json.dumps(raw_ex))
-        if ret == 0:
+        applied_exports = export_mgr.apply_export(cluster_id, json.dumps(raw_ex))
+        if not applied_exports.has_error:
             return self._get_schema_export(
                 export_mgr.get_export_by_pseudo(cluster_id, pseudo))
-        raise NFSException(f"Export creation failed {err}")
+        raise NFSException(f"Export creation failed {applied_exports.changes[0].msg}")
 
     @EndpointDoc("Get an NFS-Ganesha export",
                  parameters={
@@ -192,11 +192,11 @@ def set(self, cluster_id, export_id, path, pseudo, access_type,
         }
 
         export_mgr = mgr.remote('nfs', 'fetch_nfs_export_obj')
-        ret, _, err = export_mgr.apply_export(cluster_id, json.dumps(raw_ex))
-        if ret == 0:
+        applied_exports = export_mgr.apply_export(cluster_id, json.dumps(raw_ex))
+        if not applied_exports.has_error:
             return self._get_schema_export(
                 export_mgr.get_export_by_pseudo(cluster_id, pseudo))
-        raise NFSException(f"Failed to update export: {err}")
+        raise NFSException(f"Export creation failed {applied_exports.changes[0].msg}")
 
     @NfsTask('delete', {'cluster_id': '{cluster_id}',
                         'export_id': '{export_id}'}, 2.0)

src/pybind/mgr/dashboard/tests/test_nfs.py

@@ -4,6 +4,8 @@
 from unittest.mock import Mock, patch
 from urllib.parse import urlencode
 
+from nfs.export import AppliedExportResults
+
 from .. import mgr
 from ..controllers._version import APIVersion
 from ..controllers.nfs import NFSGaneshaExports, NFSGaneshaUi
@@ -36,6 +38,8 @@ class NFSGaneshaExportsTest(ControllerTestCase):
         "clients": []
     }
 
+    _applied_export = AppliedExportResults()
+
     @classmethod
     def setUpClass(cls):
         super().setUpClass()
@@ -71,23 +75,24 @@ def test_get_export(self):
     def test_create_export(self):
         export_mgr = Mock()
         created_nfs_export = deepcopy(self._nfs_module_export)
+        applied_nfs_export = deepcopy(self._applied_export)
         created_nfs_export['pseudo'] = 'new-pseudo'
         created_nfs_export['export_id'] = 2
         export_mgr.get_export_by_pseudo.side_effect = [None, created_nfs_export]
-        export_mgr.apply_export.return_value = (0, '', '')
+        export_mgr.apply_export.return_value = applied_nfs_export
         mgr.remote.return_value = export_mgr
 
         export_create_body = deepcopy(self._expected_export)
         del export_create_body['export_id']
         export_create_body['pseudo'] = created_nfs_export['pseudo']
+        applied_nfs_export.append(export_create_body)
 
         self._post('/api/nfs-ganesha/export',
                    export_create_body,
                    version=APIVersion(2, 0))
         self.assertStatus(201)
-        expected_body = export_create_body
-        expected_body['export_id'] = created_nfs_export['export_id']
-        self.assertJsonBody(export_create_body)
+        applied_nfs_export.changes[0]['export_id'] = created_nfs_export['export_id']
+        self.assertJsonBody(applied_nfs_export.changes[0])
 
     def test_create_export_with_existing_pseudo_fails(self):
         export_mgr = Mock()
@@ -108,19 +113,21 @@ def test_create_export_with_existing_pseudo_fails(self):
     def test_set_export(self):
         export_mgr = Mock()
         updated_nfs_export = deepcopy(self._nfs_module_export)
+        applied_nfs_export = deepcopy(self._applied_export)
         updated_nfs_export['pseudo'] = 'updated-pseudo'
         export_mgr.get_export_by_pseudo.return_value = updated_nfs_export
-        export_mgr.apply_export.return_value = (0, '', '')
+        export_mgr.apply_export.return_value = applied_nfs_export
         mgr.remote.return_value = export_mgr
 
         updated_export_body = deepcopy(self._expected_export)
         updated_export_body['pseudo'] = updated_nfs_export['pseudo']
+        applied_nfs_export.append(updated_export_body)
 
         self._put('/api/nfs-ganesha/export/myc/2',
                   updated_export_body,
                   version=APIVersion(2, 0))
         self.assertStatus(200)
-        self.assertJsonBody(updated_export_body)
+        self.assertJsonBody(applied_nfs_export.changes[0])
 
     def test_delete_export(self):
         mgr.remote = Mock(side_effect=[self._nfs_module_export, None])

src/pybind/mgr/nfs/export.py

@@ -489,6 +489,8 @@ def get_export_by_pseudo(
         export = self._fetch_export(cluster_id, pseudo_path)
         return export.to_dict() if export else None
 
+    # This method is used by the dashboard module (../dashboard/controllers/nfs.py)
+    # Do not change interface without updating the Dashboard code
     def apply_export(self, cluster_id: str, export_config: str) -> AppliedExportResults:
         try:
             exports = self._read_export_config(cluster_id, export_config)