NodeUtils: allow null values in cluster.yaml (#533)

An empty group can already be defined by specifying an empty string as value in the yaml file. For convenience, now also interpret any YAML null value as an empty set. Fixes #533.

Author: thiell

doc/sphinx/config.rst

@@ -344,6 +344,10 @@ Here is an example of **/etc/clustershell/groups.d/cluster.yaml**::
  oss: 'oss[0-15]'
  rbh: 'rbh[1-2]'
 
+
+If you wish to define an empty group (with no nodes), you can either use an
+empty string ``''`` or any valid YAML null value (``null`` or ``~``).
+
 .. highlight:: console
 
 Testing the syntax of your group file can be quickly performed through the

lib/ClusterShell/NodeUtils.py

@@ -329,11 +329,14 @@ def _load(self):
  fmt = "%s: invalid content (group source '%s' is not a dict)"
  raise GroupResolverConfigError(fmt % (self.filename, srcname))
 
- for grp in groups:
+ for grp, grpnodes in groups.items():
  if not isinstance(grp, basestring):
  fmt = '%s: %s: group name %s not a string (add quotes?)'
  raise GroupResolverConfigError(fmt % (self.filename,
  srcname, grp))
+ # GH#533: interpret null value as empty set
+ if grpnodes is None:
+ groups[grp] = ''
 
  if first:
  self._groups[srcname] = groups

tests/NodeSetGroupTest.py

@@ -1814,7 +1814,6 @@ def test_yaml_unsafe_yaml(self):
  yamlfile.close()
  tdir.cleanup()
 
-
  def test_wrong_autodir(self):
  """test wrong autodir (doesn't exist)"""
  f = make_temp_file(dedent("""
@@ -1880,3 +1879,29 @@ def test_yaml_permission_denied(self):
  yamlfile1.close()
  yamlfile2.close()
  tdir.cleanup()
+
+ def test_yaml_null_value(self):
+ """test null value in groups yaml file"""
+ tdir = make_temp_dir()
+ f = make_temp_file(dedent("""
+ [Main]
+ default: yaml
+ autodir: %s
+ """ % tdir.name).encode('ascii'))
+ yamlfile = make_temp_file(dedent("""
+ yaml:
+ c0: nid[0001-0032]
+ c1:
+ c0r7: nid[0017-0032]
+ """).encode('ascii'), suffix=".yaml", dir=tdir.name)
+ try:
+ res = GroupResolverConfig(f.name)
+ nodeset = NodeSet.fromall(resolver=res)
+ self.assertEqual(str(nodeset), "nid[0001-0032]")
+ nodeset = NodeSet("@c1", resolver=res)
+ self.assertEqual(len(nodeset), 0)
+ self.assertEqual(str(nodeset), "")
+ finally:
+ yamlfile.close()
+ tdir.cleanup()
+