diff --git a/tempest/cmd/init.py b/tempest/cmd/init.py
index e3788ab..bf7289a 100644
--- a/tempest/cmd/init.py
+++ b/tempest/cmd/init.py
@@ -89,18 +89,28 @@
         with open(testr_conf_path, 'w+') as testr_conf_file:
             testr_conf_file.write(testr_conf)
 
-    def update_local_conf(self, conf_path, lock_dir, log_dir):
+    def get_configparser(self, conf_path):
         config_parse = moves.configparser.SafeConfigParser()
         config_parse.optionxform = str
-        with open(conf_path, 'a+') as conf_file:
-            # Set local lock_dir in tempest conf
-            if not config_parse.has_section('oslo_concurrency'):
-                config_parse.add_section('oslo_concurrency')
-            config_parse.set('oslo_concurrency', 'lock_path', lock_dir)
-            # Set local log_dir in tempest conf
-            config_parse.set('DEFAULT', 'log_dir', log_dir)
-            # Set default log filename to tempest.log
-            config_parse.set('DEFAULT', 'log_file', 'tempest.log')
+        # get any existing values if a config file already exists
+        if os.path.isfile(conf_path):
+            # use read() for Python 2 and 3 compatibility
+            config_parse.read(conf_path)
+        return config_parse
+
+    def update_local_conf(self, conf_path, lock_dir, log_dir):
+        config_parse = self.get_configparser(conf_path)
+        # Set local lock_dir in tempest conf
+        if not config_parse.has_section('oslo_concurrency'):
+            config_parse.add_section('oslo_concurrency')
+        config_parse.set('oslo_concurrency', 'lock_path', lock_dir)
+        # Set local log_dir in tempest conf
+        config_parse.set('DEFAULT', 'log_dir', log_dir)
+        # Set default log filename to tempest.log
+        config_parse.set('DEFAULT', 'log_file', 'tempest.log')
+
+        # write out a new file with the updated configurations
+        with open(conf_path, 'w+') as conf_file:
             config_parse.write(conf_file)
 
     def copy_config(self, etc_dir, config_dir):
diff --git a/tempest/tests/cmd/test_tempest_init.py b/tempest/tests/cmd/test_tempest_init.py
index 031bf4d..2844371 100644
--- a/tempest/tests/cmd/test_tempest_init.py
+++ b/tempest/tests/cmd/test_tempest_init.py
@@ -45,6 +45,7 @@
         init_cmd = init.TempestInit(None, None)
         local_sample_conf_file = os.path.join(etc_dir_path,
                                               'tempest.conf.sample')
+
         # Verify no sample config file exist
         self.assertFalse(os.path.isfile(local_sample_conf_file))
         init_cmd.generate_sample_config(local_dir.path)
@@ -53,6 +54,52 @@
         self.assertTrue(os.path.isfile(local_sample_conf_file))
         self.assertGreater(os.path.getsize(local_sample_conf_file), 0)
 
+    def test_update_local_conf(self):
+        local_dir = self.useFixture(fixtures.TempDir())
+        etc_dir_path = os.path.join(local_dir.path, 'etc/')
+        os.mkdir(etc_dir_path)
+        lock_dir = os.path.join(local_dir.path, 'tempest_lock')
+        config_path = os.path.join(etc_dir_path, 'tempest.conf')
+        log_dir = os.path.join(local_dir.path, 'logs')
+
+        init_cmd = init.TempestInit(None, None)
+
+        # Generate the config file
+        init_cmd.generate_sample_config(local_dir.path)
+
+        # Create a conf file with populated values
+        config_parser_pre = init_cmd.get_configparser(config_path)
+        with open(config_path, 'w+') as conf_file:
+            # create the same section init will check for and add values to
+            config_parser_pre.add_section('oslo_concurrency')
+            config_parser_pre.set('oslo_concurrency', 'TEST', local_dir.path)
+            # create a new section
+            config_parser_pre.add_section('TEST')
+            config_parser_pre.set('TEST', 'foo', "bar")
+            config_parser_pre.write(conf_file)
+
+        # Update the config file the same way tempest init does
+        init_cmd.update_local_conf(config_path, lock_dir, log_dir)
+
+        # parse the new config file to verify it
+        config_parser_post = init_cmd.get_configparser(config_path)
+
+        # check that our value in oslo_concurrency wasn't overwritten
+        self.assertTrue(config_parser_post.has_section('oslo_concurrency'))
+        self.assertEqual(config_parser_post.get('oslo_concurrency', 'TEST'),
+                         local_dir.path)
+        # check that the lock directory was set correctly
+        self.assertEqual(config_parser_post.get('oslo_concurrency',
+                                                'lock_path'), lock_dir)
+
+        # check that our new section still exists and wasn't modified
+        self.assertTrue(config_parser_post.has_section('TEST'))
+        self.assertEqual(config_parser_post.get('TEST', 'foo'), 'bar')
+
+        # check that the DEFAULT values are correct
+        # NOTE(auggy): has_section ignores DEFAULT
+        self.assertEqual(config_parser_post.get('DEFAULT', 'log_dir'), log_dir)
+
     def test_create_working_dir_with_existing_local_dir_non_empty(self):
         fake_local_dir = self.useFixture(fixtures.TempDir())
         fake_local_conf_dir = self.useFixture(fixtures.TempDir())