Merge pull request ceph#44870 from phlogistonjohn/jjm-nfs-cleanups2

mgr/nfs: support managing exports without orchestration enabled 

Reviewed-by: Ramana Raja <rraja@redhat.com>

doc/mgr/nfs.rst

@@ -533,20 +533,26 @@ The NFS log level can be adjusted using `nfs cluster config set` command (see :r
 Manual Ganesha deployment
 =========================
 
-It may be possible to deploy and manage the NFS ganesha daemons manually
-instead of allowing cephadm or rook to do so.
+It may be possible to deploy and manage the NFS ganesha daemons without
+orchestration frameworks such as cephadm or rook.
 
 .. note:: Manual configuration is not tested or fully documented; your
           mileage may vary. If you make this work, please help us by
           updating this documentation.
 
-Known issues
+Limitations
 ------------
 
-* The ``mgr/nfs`` module enumerates NFS clusters via the orchestrator API; if NFS is
-  not managed by the orchestrator (e.g., cephadm or rook) then this will not work.  It
-  may be possible to create the cluster, mark the cephadm service as 'unmanaged', but this
-  is awkward and not ideal.
+If no orchestrator module is enabled for the Ceph Manager the NFS cluster
+management commands, such as those starting with ``ceph nfs cluster``, will not
+function. However, commands that manage NFS exports, like those prefixed with
+``ceph nfs export`` are expected to work as long as the necessary RADOS objects
+have already been created. The exact RADOS objects required are not documented
+at this time as support for this feature is incomplete. A curious reader can
+find some details about the object by reading the source code for the
+``mgr/nfs`` module (found in the ceph source tree under
+``src/pybind/mgr/nfs``).
+
 
 Requirements
 ------------

src/pybind/mgr/nfs/export.py

@@ -1,17 +1,29 @@
 import errno
 import json
 import logging
-from typing import List, Any, Dict, Tuple, Optional, TYPE_CHECKING, TypeVar, Callable, cast
+from typing import (
+    List,
+    Any,
+    Dict,
+    Tuple,
+    Optional,
+    TYPE_CHECKING,
+    TypeVar,
+    Callable,
+    Set,
+    cast)
 from os.path import normpath
 
-from rados import TimedOut, ObjectNotFound, Rados
+from rados import TimedOut, ObjectNotFound, Rados, LIBRADOS_ALL_NSPACES
 
+from orchestrator import NoOrchestrator
 from mgr_module import NFS_POOL_NAME as POOL_NAME, NFS_GANESHA_SUPPORTED_FSALS
 
 from .export_utils import GaneshaConfParser, Export, RawBlock, CephFSFSAL, RGWFSAL
 from .exception import NFSException, NFSInvalidOperation, FSNotFound, \
     ClusterNotFound
 from .utils import (
+    CONF_PREFIX,
     EXPORT_PREFIX,
     USER_CONF_PREFIX,
     export_obj_name,
@@ -37,7 +49,14 @@ def cluster_check(
         """
         This method checks if cluster exists
         """
-        if kwargs['cluster_id'] not in available_clusters(export.mgr):
+        try:
+            clusters = set(available_clusters(export.mgr))
+        except NoOrchestrator:
+            clusters = nfs_rados_configs(export.mgr.rados)
+        cluster_id: str = kwargs['cluster_id']
+        log.debug("checking for %r in known nfs clusters: %r",
+                  cluster_id, clusters)
+        if cluster_id not in clusters:
             return -errno.ENOENT, "", "Cluster does not exist"
         return func(export, *args, **kwargs)
     return cast(FuncT, cluster_check)
@@ -138,6 +157,21 @@ def check_user_config(self) -> bool:
         return False
 
 
+def nfs_rados_configs(rados: 'Rados', nfs_pool: str = POOL_NAME) -> Set[str]:
+    """Return a set of all the namespaces in the nfs_pool where nfs
+    configuration objects are found. The namespaces also correspond
+    to the cluster ids.
+    """
+    ns: Set[str] = set()
+    prefixes = (EXPORT_PREFIX, CONF_PREFIX, USER_CONF_PREFIX)
+    with rados.open_ioctx(nfs_pool) as ioctx:
+        ioctx.set_namespace(LIBRADOS_ALL_NSPACES)
+        for obj in ioctx.list_objects():
+            if obj.key.startswith(prefixes):
+                ns.add(obj.nspace)
+    return ns
+
+
 class ExportMgr:
     def __init__(
             self,