diff --git a/tempest/api/compute/servers/test_instance_actions.py b/tempest/api/compute/servers/test_instance_actions.py
index a229df8..e50881f 100644
--- a/tempest/api/compute/servers/test_instance_actions.py
+++ b/tempest/api/compute/servers/test_instance_actions.py
@@ -28,17 +28,17 @@
     @classmethod
     def resource_setup(cls):
         super(InstanceActionsTestJSON, cls).resource_setup()
-        server = cls.create_test_server(wait_until='ACTIVE')
-        cls.request_id = server.response['x-compute-request-id']
-        cls.server_id = server['id']
+        cls.server = cls.create_test_server(wait_until='ACTIVE')
+        cls.request_id = cls.server.response['x-compute-request-id']
 
     @test.idempotent_id('77ca5cc5-9990-45e0-ab98-1de8fead201a')
     def test_list_instance_actions(self):
         # List actions of the provided server
-        self.client.reboot_server(self.server_id, type='HARD')
-        waiters.wait_for_server_status(self.client, self.server_id, 'ACTIVE')
+        self.client.reboot_server(self.server['id'], type='HARD')
+        waiters.wait_for_server_status(self.client,
+                                       self.server['id'], 'ACTIVE')
 
-        body = (self.client.list_instance_actions(self.server_id)
+        body = (self.client.list_instance_actions(self.server['id'])
                 ['instanceActions'])
         self.assertEqual(len(body), 2, str(body))
         self.assertEqual(sorted([i['action'] for i in body]),
@@ -48,8 +48,8 @@
     def test_get_instance_action(self):
         # Get the action details of the provided server
         body = self.client.show_instance_action(
-            self.server_id, self.request_id)['instanceAction']
-        self.assertEqual(self.server_id, body['instance_uuid'])
+            self.server['id'], self.request_id)['instanceAction']
+        self.assertEqual(self.server['id'], body['instance_uuid'])
         self.assertEqual('create', body['action'])
 
 
diff --git a/tempest/api/compute/servers/test_instance_actions_negative.py b/tempest/api/compute/servers/test_instance_actions_negative.py
index 54ec6aa..33fed08 100644
--- a/tempest/api/compute/servers/test_instance_actions_negative.py
+++ b/tempest/api/compute/servers/test_instance_actions_negative.py
@@ -29,8 +29,7 @@
     @classmethod
     def resource_setup(cls):
         super(InstanceActionsNegativeTestJSON, cls).resource_setup()
-        server = cls.create_test_server(wait_until='ACTIVE')
-        cls.server_id = server['id']
+        cls.server = cls.create_test_server(wait_until='ACTIVE')
 
     @test.attr(type=['negative'])
     @test.idempotent_id('67e1fce6-7ec2-45c6-92d4-0a8f1a632910')
@@ -46,4 +45,4 @@
     def test_get_instance_action_invalid_request(self):
         # Get the action details of the provided server with invalid request
         self.assertRaises(lib_exc.NotFound, self.client.show_instance_action,
-                          self.server_id, '999')
+                          self.server['id'], '999')
diff --git a/tempest/api/compute/servers/test_server_metadata.py b/tempest/api/compute/servers/test_server_metadata.py
index 9c07677..cb66e81 100644
--- a/tempest/api/compute/servers/test_server_metadata.py
+++ b/tempest/api/compute/servers/test_server_metadata.py
@@ -28,18 +28,17 @@
     @classmethod
     def resource_setup(cls):
         super(ServerMetadataTestJSON, cls).resource_setup()
-        server = cls.create_test_server(metadata={}, wait_until='ACTIVE')
-        cls.server_id = server['id']
+        cls.server = cls.create_test_server(metadata={}, wait_until='ACTIVE')
 
     def setUp(self):
         super(ServerMetadataTestJSON, self).setUp()
         meta = {'key1': 'value1', 'key2': 'value2'}
-        self.client.set_server_metadata(self.server_id, meta)['metadata']
+        self.client.set_server_metadata(self.server['id'], meta)['metadata']
 
     @test.idempotent_id('479da087-92b3-4dcf-aeb3-fd293b2d14ce')
     def test_list_server_metadata(self):
         # All metadata key/value pairs for a server should be returned
-        resp_metadata = (self.client.list_server_metadata(self.server_id)
+        resp_metadata = (self.client.list_server_metadata(self.server['id'])
                          ['metadata'])
 
         # Verify the expected metadata items are in the list
@@ -51,12 +50,12 @@
         # The server's metadata should be replaced with the provided values
         # Create a new set of metadata for the server
         req_metadata = {'meta2': 'data2', 'meta3': 'data3'}
-        self.client.set_server_metadata(self.server_id,
+        self.client.set_server_metadata(self.server['id'],
                                         req_metadata)['metadata']
 
         # Verify the expected values are correct, and that the
         # previous values have been removed
-        resp_metadata = (self.client.list_server_metadata(self.server_id)
+        resp_metadata = (self.client.list_server_metadata(self.server['id'])
                          ['metadata'])
         self.assertEqual(resp_metadata, req_metadata)
 
@@ -65,10 +64,10 @@
         # The server's metadata values should be updated to the
         # provided values
         meta = {'key1': 'alt1', 'key3': 'value3'}
-        self.client.update_server_metadata(self.server_id, meta)
+        self.client.update_server_metadata(self.server['id'], meta)
 
         # Verify the values have been updated to the proper values
-        resp_metadata = (self.client.list_server_metadata(self.server_id)
+        resp_metadata = (self.client.list_server_metadata(self.server['id'])
                          ['metadata'])
         expected = {'key1': 'alt1', 'key2': 'value2', 'key3': 'value3'}
         self.assertEqual(expected, resp_metadata)
@@ -78,8 +77,8 @@
         # The original metadata should not be lost if empty metadata body is
         # passed
         meta = {}
-        self.client.update_server_metadata(self.server_id, meta)
-        resp_metadata = (self.client.list_server_metadata(self.server_id)
+        self.client.update_server_metadata(self.server['id'], meta)
+        resp_metadata = (self.client.list_server_metadata(self.server['id'])
                          ['metadata'])
         expected = {'key1': 'value1', 'key2': 'value2'}
         self.assertEqual(expected, resp_metadata)
@@ -87,7 +86,7 @@
     @test.idempotent_id('3043c57d-7e0e-49a6-9a96-ad569c265e6a')
     def test_get_server_metadata_item(self):
         # The value for a specific metadata key should be returned
-        meta = self.client.show_server_metadata_item(self.server_id,
+        meta = self.client.show_server_metadata_item(self.server['id'],
                                                      'key2')['meta']
         self.assertEqual('value2', meta['key2'])
 
@@ -96,10 +95,10 @@
         # The item's value should be updated to the provided value
         # Update the metadata value
         meta = {'nova': 'alt'}
-        self.client.set_server_metadata_item(self.server_id, 'nova', meta)
+        self.client.set_server_metadata_item(self.server['id'], 'nova', meta)
 
         # Verify the meta item's value has been updated
-        resp_metadata = (self.client.list_server_metadata(self.server_id)
+        resp_metadata = (self.client.list_server_metadata(self.server['id'])
                          ['metadata'])
         expected = {'key1': 'value1', 'key2': 'value2', 'nova': 'alt'}
         self.assertEqual(expected, resp_metadata)
@@ -107,10 +106,10 @@
     @test.idempotent_id('127642d6-4c7b-4486-b7cd-07265a378658')
     def test_delete_server_metadata_item(self):
         # The metadata value/key pair should be deleted from the server
-        self.client.delete_server_metadata_item(self.server_id, 'key1')
+        self.client.delete_server_metadata_item(self.server['id'], 'key1')
 
         # Verify the metadata item has been removed
-        resp_metadata = (self.client.list_server_metadata(self.server_id)
+        resp_metadata = (self.client.list_server_metadata(self.server['id'])
                          ['metadata'])
         expected = {'key2': 'value2'}
         self.assertEqual(expected, resp_metadata)
diff --git a/tempest/api/compute/servers/test_server_metadata_negative.py b/tempest/api/compute/servers/test_server_metadata_negative.py
index cbe70e2..aae9101 100644
--- a/tempest/api/compute/servers/test_server_metadata_negative.py
+++ b/tempest/api/compute/servers/test_server_metadata_negative.py
@@ -31,9 +31,7 @@
     def resource_setup(cls):
         super(ServerMetadataNegativeTestJSON, cls).resource_setup()
         cls.tenant_id = cls.client.tenant_id
-        server = cls.create_test_server(metadata={}, wait_until='ACTIVE')
-
-        cls.server_id = server['id']
+        cls.server = cls.create_test_server(metadata={}, wait_until='ACTIVE')
 
     @test.attr(type=['negative'])
     @test.idempotent_id('fe114a8f-3a57-4eff-9ee2-4e14628df049')
@@ -87,7 +85,7 @@
         meta = {'testkey': 'testvalue'}
         self.assertRaises(lib_exc.BadRequest,
                           self.client.set_server_metadata_item,
-                          self.server_id, 'key', meta)
+                          self.server['id'], 'key', meta)
 
     @test.attr(type=['negative'])
     @test.idempotent_id('0df38c2a-3d4e-4db5-98d8-d4d9fa843a12')
@@ -118,7 +116,7 @@
         meta = {'': 'data1'}
         self.assertRaises(lib_exc.BadRequest,
                           self.client.update_server_metadata,
-                          self.server_id, meta=meta)
+                          self.server['id'], meta=meta)
 
     @test.attr(type=['negative'])
     @test.idempotent_id('6bbd88e1-f8b3-424d-ba10-ae21c45ada8d')
@@ -146,14 +144,14 @@
             req_metadata['key' + str(num)] = 'val' + str(num)
         self.assertRaises((lib_exc.OverLimit, lib_exc.Forbidden),
                           self.client.set_server_metadata,
-                          self.server_id, req_metadata)
+                          self.server['id'], req_metadata)
 
         # A 403 Forbidden or 413 Overlimit (old behaviour) exception
         # will be raised while exceeding metadata items limit for
         # tenant.
         self.assertRaises((lib_exc.Forbidden, lib_exc.OverLimit),
                           self.client.update_server_metadata,
-                          self.server_id, req_metadata)
+                          self.server['id'], req_metadata)
 
     @test.attr(type=['negative'])
     @test.idempotent_id('96100343-7fa9-40d8-80fa-d29ef588ce1c')
@@ -163,7 +161,7 @@
         meta = {'': 'data1'}
         self.assertRaises(lib_exc.BadRequest,
                           self.client.set_server_metadata,
-                          self.server_id, meta=meta)
+                          self.server['id'], meta=meta)
 
     @test.attr(type=['negative'])
     @test.idempotent_id('64a91aee-9723-4863-be44-4c9d9f1e7d0e')
@@ -173,4 +171,4 @@
         meta = {'meta1': 'data1'}
         self.assertRaises(lib_exc.BadRequest,
                           self.client.set_server_metadata,
-                          self.server_id, meta=meta, no_metadata_field=True)
+                          self.server['id'], meta=meta, no_metadata_field=True)
diff --git a/tempest/api/compute/servers/test_virtual_interfaces.py b/tempest/api/compute/servers/test_virtual_interfaces.py
index e620e03..08c34d3 100644
--- a/tempest/api/compute/servers/test_virtual_interfaces.py
+++ b/tempest/api/compute/servers/test_virtual_interfaces.py
@@ -40,8 +40,7 @@
     @classmethod
     def resource_setup(cls):
         super(VirtualInterfacesTestJSON, cls).resource_setup()
-        server = cls.create_test_server(wait_until='ACTIVE')
-        cls.server_id = server['id']
+        cls.server = cls.create_test_server(wait_until='ACTIVE')
 
     @test.idempotent_id('96c4e2ef-5e4d-4d7f-87f5-fed6dca18016')
     @test.services('network')
@@ -53,9 +52,9 @@
             # TODO(mriedem): After a microversion implements the API for
             # neutron, a 400 should be a failure for nova-network and neutron.
             with testtools.ExpectedException(exceptions.BadRequest):
-                self.client.list_virtual_interfaces(self.server_id)
+                self.client.list_virtual_interfaces(self.server['id'])
         else:
-            output = self.client.list_virtual_interfaces(self.server_id)
+            output = self.client.list_virtual_interfaces(self.server['id'])
             self.assertIsNotNone(output)
             virt_ifaces = output
             self.assertNotEqual(0, len(virt_ifaces['virtual_interfaces']),
diff --git a/tempest/api/compute/test_live_block_migration_negative.py b/tempest/api/compute/test_live_block_migration_negative.py
index ffd274f..bd2b185 100644
--- a/tempest/api/compute/test_live_block_migration_negative.py
+++ b/tempest/api/compute/test_live_block_migration_negative.py
@@ -49,9 +49,8 @@
         # Migrating to an invalid host should not change the status
         target_host = data_utils.rand_name('host')
         server = self.create_test_server(wait_until="ACTIVE")
-        server_id = server['id']
 
         self.assertRaises(lib_exc.BadRequest, self._migrate_server_to,
-                          server_id, target_host)
-        waiters.wait_for_server_status(self.servers_client, server_id,
+                          server['id'], target_host)
+        waiters.wait_for_server_status(self.servers_client, server['id'],
                                        'ACTIVE')
diff --git a/tempest/clients.py b/tempest/clients.py
index be6bc02..f358d91 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -19,7 +19,6 @@
 
 from tempest.common import negative_rest_client
 from tempest import config
-from tempest import exceptions
 from tempest.lib import auth
 from tempest.lib import exceptions as lib_exc
 from tempest.lib.services import clients
@@ -350,7 +349,7 @@
     # kwargs for auth provider match the common ones used by service clients
     default_params = config.service_client_config()
     if credentials is None:
-        raise exceptions.InvalidCredentials(
+        raise lib_exc.InvalidCredentials(
             'Credentials must be specified')
     auth_provider_class, auth_url = get_auth_provider_class(
         credentials)