Support NSX tag limitations

The NSX has various tag limitations. For example the maximum
length of the tags and the maximum amount of tags per resource.
This may increase with NSX versions.

This patch enables the library to learn from the NSX the tag limits.

Change-Id: Ie2eac9c51a36496908140018d7ca1d15ed0e9d58

vmware_nsxlib/tests/unit/v3/test_utils.py

@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import mock
+
 from vmware_nsxlib.tests.unit.v3 import nsxlib_testcase
 from vmware_nsxlib.v3 import exceptions
 from vmware_nsxlib.v3 import nsx_constants
@@ -250,6 +252,17 @@ class TestNsxV3Utils(nsxlib_testcase.NsxClientTestCase):
         self.assertRaises(exceptions.NsxLibInvalidInput, func_to_fail, 99)
         self.assertEqual(max_retries, total_count['val'])
 
+    @mock.patch.object(utils, '_update_max_tags')
+    @mock.patch.object(utils, '_update_tag_length')
+    @mock.patch.object(utils, '_update_resource_length')
+    def test_update_limits(self, _update_resource_length,
+                           _update_tag_length, _update_max_tags):
+        limits = utils.TagLimits(1, 2, 3)
+        utils.update_tag_limits(limits)
+        _update_resource_length.assert_called_with(1)
+        _update_tag_length.assert_called_with(2)
+        _update_max_tags.assert_called_with(3)
+
 
 class NsxFeaturesTestCase(nsxlib_testcase.NsxLibTestCase):
 

vmware_nsxlib/v3/__init__.py

@@ -194,6 +194,23 @@ class NsxLibBase(object):
             reason = _('Missing key:%s in tags') % str(e)
             raise exceptions.NsxSearchInvalidQuery(reason=reason)
 
+    def get_tag_limits(self):
+        try:
+            result = self.client.url_get('spec/vmware/types/Tag')
+            scope_length = result['properties']['scope']['maxLength']
+            tag_length = result['properties']['tag']['maxLength']
+        except Exception as e:
+            LOG.error("Unable to read tag limits. Reason: %s", e)
+            scope_length = utils.MAX_RESOURCE_TYPE_LEN
+            tag_length = utils.MAX_TAG_LEN
+        try:
+            result = self.client.url_get('spec/vmware/types/ManagedResource')
+            max_tags = result['properties']['tags']['maxItems']
+        except Exception as e:
+            LOG.error("Unable to read maximum tags. Reason: %s", e)
+            max_tags = utils.MAX_TAGS
+        return utils.TagLimits(scope_length, tag_length, max_tags)
+
 
 class NsxLib(NsxLibBase):
 
@@ -255,6 +272,9 @@ class NsxLib(NsxLibBase):
             self.client, self.nsxlib_config, nsxlib=self)
         self.vif = core_resources.NsxLibFabricVirtualInterface(
             self.client, self.nsxlib_config, nsxlib=self)
+        # Update tag limits
+        self.tag_limits = self.get_tag_limits()
+        utils.update_tag_limits(self.tag_limits)
 
     @property
     def keepalive_section(self):

vmware_nsxlib/v3/utils.py

@@ -14,6 +14,7 @@
 #    under the License.
 
 import abc
+import collections
 import inspect
 import re
 import time
@@ -27,8 +28,15 @@ from vmware_nsxlib.v3 import exceptions as nsxlib_exceptions
 
 LOG = log.getLogger(__name__)
 
+TagLimits = collections.namedtuple('TagLimits',
+                                   ['scope_length', 'tag_length', 'max_tags'])
+
+# The tag limits may change in the NSX. We set the default values to be those
+# in NSX 2.0. If the NSX returns different values we update these globals.
 MAX_RESOURCE_TYPE_LEN = 20
 MAX_TAG_LEN = 40
+MAX_TAGS = 15
+
 DEFAULT_MAX_ATTEMPTS = 10
 DEFAULT_CACHE_AGE_SEC = 600
 INJECT_HEADERS_CALLBACK = None
@@ -51,6 +59,27 @@ def set_inject_headers_callback(callback):
     INJECT_HEADERS_CALLBACK = callback
 
 
+def _update_resource_length(length):
+    global MAX_RESOURCE_TYPE_LEN
+    MAX_RESOURCE_TYPE_LEN = length
+
+
+def _update_tag_length(length):
+    global MAX_TAG_LEN
+    MAX_TAG_LEN = length
+
+
+def _update_max_tags(max_tags):
+    global MAX_TAGS
+    MAX_TAGS = max_tags
+
+
+def update_tag_limits(limits):
+    _update_resource_length(limits.scope_length)
+    _update_tag_length(limits.tag_length)
+    _update_max_tags(limits.max_tags)
+
+
 def _validate_resource_type_length(resource_type):
     # Add in a validation to ensure that we catch this at build time
     if len(resource_type) > MAX_RESOURCE_TYPE_LEN: