Extract generate_hostid method into utils.py

This would be used in instance action API to show the hostId
to non-admin user.

This patch propose to extract the generate_hostid method
into utils.

trivial fix

Change-Id: I00d29e9fd80e6b8f7ba3bbd8e82dde9d4cb1522f

nova/api/openstack/compute/views/servers.py

@@ -14,8 +14,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import hashlib
-
 from oslo_log import log as logging
 
 from nova.api.openstack import api_version_request
@@ -134,7 +132,7 @@ class ViewBuilder(common.ViewBuilder):
                 "tenant_id": instance.get("project_id") or "",
                 "user_id": instance.get("user_id") or "",
                 "metadata": self._get_metadata(instance),
-                "hostId": self._get_host_id(instance) or "",
+                "hostId": self._get_host_id(instance),
                 "image": self._get_image(request, instance),
                 "flavor": self._get_flavor(request, instance,
                                            show_extra_specs),
@@ -236,10 +234,7 @@ class ViewBuilder(common.ViewBuilder):
     def _get_host_id(instance):
         host = instance.get("host")
         project = str(instance.get("project_id"))
-        if host:
-            data = (project + host).encode('utf-8')
-            sha_hash = hashlib.sha224(data)
-            return sha_hash.hexdigest()
+        return utils.generate_hostid(host, project)
 
     def _get_addresses(self, request, instance, extend_address=False):
         context = request.environ["nova.context"]

nova/tests/unit/test_utils.py

@@ -239,6 +239,16 @@ class GenericUtilsTestCase(test.NoDBTestCase):
             utils.ssh_execute('remotehost', 'ls', '-l')
         mock_method.assert_called_once_with(*expected_args)
 
+    def test_generate_hostid(self):
+        host = 'host'
+        project_id = '9b9e3c847e904b0686e8ffb20e4c6381'
+        hostId = 'fa123c6f74efd4aad95f84096f9e187caa0625925a9e7837b2b46792'
+        self.assertEqual(utils.generate_hostid(host, project_id), hostId)
+
+    def test_generate_hostid_with_none_host(self):
+        project_id = '9b9e3c847e904b0686e8ffb20e4c6381'
+        self.assertEqual(utils.generate_hostid(None, project_id), '')
+
 
 class TestCachedFile(test.NoDBTestCase):
     @mock.patch('os.path.getmtime', return_value=1)

nova/utils.py

@@ -1380,3 +1380,21 @@ def supports_direct_io(dirpath):
             pass
 
     return hasDirectIO
+
+
+def generate_hostid(host, project_id):
+    """Generate an obfuscated host id representing the host.
+
+    This is a hashed value so will not actually look like a hostname, and is
+    hashed with data from the project_id.
+
+    :param host: The name of the compute host.
+    :param project_id: The UUID of the project.
+    :return: An obfuscated hashed host id string, return "" if host is empty
+    """
+    if host:
+        data = (project_id + host).encode('utf-8')
+        sha_hash = hashlib.sha224(data)
+        return sha_hash.hexdigest()
+    else:
+        return ""