Allow update host API to add new extra capabilities

The update host API can only update existing extra capabilities.
However, we can support adding new extra capabilities to hosts without
API change.

With this patch, Blazar can both create and update extra capabilities
via the update host API.

Partial-Bug: #1674524
Change-Id: Ic9bd743a1c31858db9390a3379dc19e1e54327a8

blazar/plugins/oshosts/host_plugin.py

@@ -296,8 +296,6 @@ class PhysicalHostPlugin(base.BasePlugin, nova.NovaClientWrapper):
                 return None
 
     def update_computehost(self, host_id, values):
-        # NOTE (sbauza): Only update existing extra capabilites, don't create
-        #  other ones
         if values:
             cant_update_extra_capability = []
             for value in values:
@@ -305,17 +303,29 @@ class PhysicalHostPlugin(base.BasePlugin, nova.NovaClientWrapper):
                     host_id,
                     value,
                 )
-                for raw_capability in capabilities:
-                    capability = {
+                if capabilities:
+                    for raw_capability in capabilities:
+                        capability = {
+                            'capability_name': value,
+                            'capability_value': values[value],
+                        }
+                        try:
+                            db_api.host_extra_capability_update(
+                                raw_capability['id'], capability)
+                        except (db_ex.BlazarDBException, RuntimeError):
+                            cant_update_extra_capability.append(
+                                raw_capability['capability_name'])
+                else:
+                    new_capability = {
+                        'computehost_id': host_id,
                         'capability_name': value,
                         'capability_value': values[value],
                     }
                     try:
-                        db_api.host_extra_capability_update(
-                            raw_capability['id'], capability)
-                    except RuntimeError:
+                        db_api.host_extra_capability_create(new_capability)
+                    except (db_ex.BlazarDBException, RuntimeError):
                         cant_update_extra_capability.append(
-                            raw_capability['capability_name'])
+                            new_capability['capability_name'])
             if cant_update_extra_capability:
                 raise manager_ex.CantAddExtraCapability(
                     host=host_id,

blazar/tests/plugins/test_physical_host_plugin.py

@@ -267,6 +267,18 @@ class PhysicalHostPluginTestCase(tests.TestCase):
                           self.fake_phys_plugin.update_computehost,
                           self.fake_host_id, host_values)
 
+    def test_update_host_with_new_extra_capability(self):
+        host_values = {'buzz': 'word'}
+
+        self.db_host_extra_capability_get_all_per_name.return_value = []
+        self.fake_phys_plugin.update_computehost(self.fake_host_id,
+                                                 host_values)
+        self.db_host_extra_capability_create.assert_called_once_with({
+            'computehost_id': '1',
+            'capability_name': 'buzz',
+            'capability_value': 'word'
+        })
+
     def test_delete_host(self):
         self.fake_phys_plugin.delete_computehost(self.fake_host_id)
 

releasenotes/notes/create-extra-capabilities-in-update-host-c74ce75c88e88c67.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    The update host API now allows new extra capabilities to be created on
+    existing hosts, in addition to allowing values of existing keys to be
+    modified. However, extra capabilities cannot yet be removed due to lack of
+    API support. As a workaround, operators can delete hosts and recreate them.