Backport #30797 to 2015.8

salt/states/dockerng.py

@@ -2091,7 +2091,13 @@ def volume_present(name, driver=None, driver_opts=None):
         Name of the volume
 
     driver
-        Type of driver for that volume.
+        Type of driver for that volume.  If ``None`` and the volume
+        does not yet exist, the volume will be created using Docker's
+        default driver.  If ``None`` and the volume does exist, this
+        function does nothing, even if the existing volume's driver is
+        not the Docker default driver.  (To ensure that an existing
+        volume's driver matches the Docker default, you must
+        explicitly name Docker's default driver here.)
 
     driver_opts
         Option for tha volume driver
@@ -2145,7 +2151,7 @@ def volume_present(name, driver=None, driver_opts=None):
             return ret
     # volume exits, check if driver is the same.
     volume = volumes[0]
-    if volume['Driver'] != driver:
+    if driver is not None and volume['Driver'] != driver:
         try:
             ret['changes']['removed'] = __salt__['dockerng.remove_volume'](name)
         except Exception as exc:

tests/unit/states/dockerng_test.py

@@ -506,22 +506,94 @@ def test_volume_present(self):
         '''
         Test dockerng.volume_present
         '''
-        dockerng_create_volume = Mock(return_value='created')
+        volumes = []
+        default_driver = 'dummy_default'
+
+        def create_volume(name, driver=None, driver_opts=None):
+            for v in volumes:
+                # volume_present should never try to add a conflicting
+                # volume
+                self.assertNotEqual(v['Name'], name)
+            if driver is None:
+                driver = default_driver
+            new = {'Name': name, 'Driver': driver}
+            volumes.append(new)
+            return new
+
+        def remove_volume(name):
+            old_len = len(volumes)
+            removed = [v for v in volumes if v['Name'] == name]
+            # volume_present should not have tried to remove a volume
+            # that didn't exist
+            self.assertEqual(1, len(removed))
+            volumes.remove(removed[0])
+            return removed[0]
+
+        dockerng_create_volume = Mock(side_effect=create_volume)
         __salt__ = {'dockerng.create_volume': dockerng_create_volume,
-                    'dockerng.volumes': Mock(return_value={'Volumes': []}),
+                    'dockerng.volumes': Mock(return_value={'Volumes': volumes}),
+                    'dockerng.remove_volume': Mock(side_effect=remove_volume),
                     }
         with patch.dict(dockerng_state.__dict__,
                         {'__salt__': __salt__}):
             ret = dockerng_state.volume_present(
                 'volume_foo',
                 )
-        dockerng_create_volume.assert_called_with('volume_foo',
-                                                  driver=None,
-                                                  driver_opts=None)
-        self.assertEqual(ret, {'name': 'volume_foo',
-                               'comment': '',
-                               'changes': {'created': 'created'},
-                               'result': True})
+            dockerng_create_volume.assert_called_with('volume_foo',
+                                                      driver=None,
+                                                      driver_opts=None)
+            self.assertEqual(
+                {
+                    'name': 'volume_foo',
+                    'comment': '',
+                    'changes': {
+                        'created': {
+                            'Driver': default_driver,
+                            'Name': 'volume_foo',
+                        },
+                    },
+                    'result': True,
+                },
+                ret)
+            self.assertEqual(len(volumes), 1)
+            self.assertEqual(volumes[0]['Name'], 'volume_foo')
+            self.assertIs(volumes[0]['Driver'], default_driver)
+
+            # run it again with the same arguments
+            orig_volumes = [volumes[0].copy()]
+            ret = dockerng_state.volume_present('volume_foo')
+            self.assertEqual(
+                {
+                    'name': 'volume_foo',
+                    'comment': "Volume 'volume_foo' already exists.",
+                    'changes': {},
+                    'result': True,
+                },
+                ret)
+            self.assertEqual(orig_volumes, volumes)
+
+            # run it again, except with a different driver
+            ret = dockerng_state.volume_present('volume_foo', driver='local')
+            self.assertEqual(
+                {
+                    'name': 'volume_foo',
+                    'comment': "",
+                    'changes': {
+                        'removed': {
+                            'Driver': default_driver,
+                            'Name': 'volume_foo',
+                        },
+                        'created': {
+                            'Driver': 'local',
+                            'Name': 'volume_foo',
+                        },
+                    },
+                    'result': True,
+                },
+                ret)
+            mod_orig_volumes = [orig_volumes[0].copy()]
+            mod_orig_volumes[0]['Driver'] = 'local'
+            self.assertEqual(mod_orig_volumes, volumes)
 
     def test_volume_present_with_another_driver(self):
         '''