mgr/volumes: add arg to fs volume create for mds daemons placement

doc/cephfs/fs-volumes.rst

@@ -43,7 +43,7 @@ FS Volumes
 
 Create a volume using::
 
-    $ ceph fs volume create <vol_name>
+    $ ceph fs volume create <vol_name> [<placement>]
 
 This creates a CephFS file system and its data and metadata pools. It also tries
 to create MDSes for the filesystem using the enabled ceph-mgr orchestrator

src/pybind/mgr/orchestrator/_interface.py

@@ -1164,6 +1164,47 @@ def validate(self):
         if self.count is not None and self.count <= 0:
             raise Exception("num/count must be > 1")
 
+    @classmethod
+    def from_strings(cls, strings):
+        # type: (Optional[List[str]]) -> PlacementSpec
+        """
+        A single integer is parsed as a count:
+        >>> PlacementSpec.from_strings('3'.split())
+        PlacementSpec(count=3)
+        A list of names is parsed as host specifications:
+        >>> PlacementSpec.from_strings('host1 host2'.split())
+        PlacementSpec(label=[HostSpec(hostname='host1', network='', name=''), HostSpec(hostname='host2', network='', name='')])
+        You can also prefix the hosts with a count as follows:
+        >>> PlacementSpec.from_strings('2 host1 host2'.split())
+        PlacementSpec(label=[HostSpec(hostname='host1', network='', name=''), HostSpec(hostname='host2', network='', name='')], count=2)
+        You can spefify labels using `label:<label>`
+        >>> PlacementSpec.from_strings('label:mon'.split())
+        PlacementSpec(label='label:mon')
+        Labels als support a count:
+        >>> PlacementSpec.from_strings('3 label:mon'.split())
+        PlacementSpec(label='label:mon', count=3)
+        >>> PlacementSpec.from_strings(None)
+        PlacementSpec()
+        """
+        strings = strings or []
+
+        count = None
+        if strings:
+            try:
+                count = int(strings[0])
+                strings = strings[1:]
+            except ValueError:
+                pass
+
+        hosts = [x for x in strings if 'label:' not in x]
+        labels = [x for x in strings if 'label:' in x]
+        if len(labels) > 1:
+            raise OrchestratorValidationError('more than one label provided: {}'.format(labels))
+
+        ps = PlacementSpec(count=count, hosts=hosts, label=labels[0] if labels else None)
+        ps.validate()
+        return ps
+
 
 def handle_type_error(method):
     @wraps(method)

src/pybind/mgr/volumes/fs/fs_util.py

@@ -33,8 +33,8 @@ def remove_filesystem(mgr, fs_name):
     command = {'prefix': 'fs rm', 'fs_name': fs_name, 'yes_i_really_mean_it': True}
     return mgr.mon_command(command)
 
-def create_mds(mgr, fs_name):
-    spec = orchestrator.ServiceSpec(fs_name)
+def create_mds(mgr, fs_name, placement):
+    spec = orchestrator.ServiceSpec(fs_name, orchestrator.PlacementSpec.from_strings(placement.split()))
     try:
         completion = mgr.apply_mds(spec)
         mgr._orchestrator_wait([completion])

src/pybind/mgr/volumes/fs/operations/volume.py

@@ -197,7 +197,7 @@ def gen_pool_names(volname):
     """
     return "cephfs.{}.meta".format(volname), "cephfs.{}.data".format(volname)
 
-def create_volume(mgr, volname):
+def create_volume(mgr, volname, placement):
     """
     create volume  (pool, filesystem and mds)
     """
@@ -220,7 +220,7 @@ def create_volume(mgr, volname):
         remove_pool(metadata_pool)
         return r, outb, outs
     # create mds
-    return create_mds(mgr, volname)
+    return create_mds(mgr, volname, placement)
 
 def delete_volume(mgr, volname):
     """

src/pybind/mgr/volumes/fs/volume.py

@@ -83,10 +83,10 @@ def volume_exception_to_retval(self, ve):
 
     ### volume operations -- create, rm, ls
 
-    def create_fs_volume(self, volname):
+    def create_fs_volume(self, volname, placement):
         if self.is_stopping():
             return -errno.ESHUTDOWN, "", "shutdown in progress"
-        return create_volume(self.mgr, volname)
+        return create_volume(self.mgr, volname, placement)
 
     def delete_fs_volume(self, volname, confirm):
         if self.is_stopping():

src/pybind/mgr/volumes/module.py

@@ -15,7 +15,8 @@ class Module(orchestrator.OrchestratorClientMixin, MgrModule):
         },
         {
             'cmd': 'fs volume create '
-                   'name=name,type=CephString ',
+                   'name=name,type=CephString '
+                   'name=placement,type=CephString,req=false ',
             'desc': "Create a CephFS volume",
             'perm': 'rw'
         },
@@ -242,7 +243,8 @@ def handle_command(self, inbuf, cmd):
 
     def _cmd_fs_volume_create(self, inbuf, cmd):
         vol_id = cmd['name']
-        return self.vc.create_fs_volume(vol_id)
+        placement = cmd.get('placement', None)
+        return self.vc.create_fs_volume(vol_id, placement)
 
     def _cmd_fs_volume_rm(self, inbuf, cmd):
         vol_name = cmd['vol_name']