Provide user friendly messages for db sync

Currently 'karbor-manage db sync' prints stacktrace if you
pass invalid value for 'version'.

This patch validates 'version' for its type and maximum
limit and displays a meaningful message to the user.

Handles DbMigrationError exception when database schema
file is not present in migration repository.

Closes-Bug: #1699893
Change-Id: I2ebc068dfee9fdba20183fb996f703bc44d7ca09

karbor/cmd/manage.py

@@ -22,6 +22,7 @@ import os
 import sys
 
 from oslo_config import cfg
+from oslo_db import exception as db_exc
 from oslo_db.sqlalchemy import migration
 from oslo_log import log as logging
 
@@ -54,11 +55,19 @@ def args(*args, **kwargs):
 class DbCommands(object):
     """Class for managing the database."""
 
-    @args('version', nargs='?', default=None,
+    @args('version', nargs='?', default=None, type=int,
           help='Database version')
     def sync(self, version=None):
         """Sync the database up to the most recent version."""
+        if version is not None and version > db.MAX_INT:
+            print(_('Version should be less than or equal to '
+                    '%(max_version)d.') % {'max_version': db.MAX_INT})
+            sys.exit(1)
+        try:
             return db_migration.db_sync(version)
+        except db_exc.DbMigrationError as ex:
+            print("Error during database migration: %s" % ex)
+            sys.exit(1)
 
     def version(self):
         """Print the current database version."""

karbor/tests/unit/test_cmd.py

@@ -17,8 +17,10 @@ try:
 except ImportError:
     import mock
 from oslo_config import cfg
+from oslo_db import exception as db_exc
 
 from karbor.cmd import api as karbor_api
+from karbor.cmd import manage as karbor_manage
 from karbor.tests import base
 from karbor import version
 
@@ -57,3 +59,28 @@ class TestKarborApiCmd(base.TestCase):
         launcher.launch_service.assert_called_once_with(server,
                                                         workers=server.workers)
         launcher.wait.assert_called_once_with()
+
+
+class TestKarborManageCmd(base.TestCase):
+    """Unit test cases for python modules under karbor/cmd/manage.py."""
+
+    def setUp(self):
+        super(TestKarborManageCmd, self).setUp()
+        sys.argv = ['karbor-manage']
+        CONF(sys.argv[1:], project='karbor', version=version.version_string())
+
+    def tearDown(self):
+        super(TestKarborManageCmd, self).tearDown()
+
+    def test_db_commands_upgrade_out_of_range(self):
+        version = 1111111111
+        db_cmds = karbor_manage.DbCommands()
+        exit = self.assertRaises(SystemExit, db_cmds.sync, version + 1)
+        self.assertEqual(1, exit.code)
+
+    @mock.patch("oslo_db.sqlalchemy.migration.db_sync")
+    def test_db_commands_script_not_present(self, db_sync):
+        db_sync.side_effect = db_exc.DbMigrationError
+        db_cmds = karbor_manage.DbCommands()
+        exit = self.assertRaises(SystemExit, db_cmds.sync, 101)
+        self.assertEqual(1, exit.code)