Avoid printing message in error level when DEVICE_METADATA|localhost …

…updates (#25)

There is error message logged on receiving `DEVICE_METADATA|localhost.hostname` update with the same value `DeviceMetaCfg.hostname`.
However, this can happen when other fields in `DEVICE_METADATA|localhost` are updated after `hostname` is recorded by `DeviceMetaCfg` because it always notifies of updates of all the fields together.
In this case, `INFO` is preferred.

scripts/hostcfgd

@@ -1355,7 +1355,13 @@ class DeviceMetaCfg(object):
 
         # Restart hostname-config service when hostname was changed.
         # Empty not allowed
-        if new_hostname and new_hostname != self.hostname:
+        if not new_hostname:
+            syslog.syslog(syslog.LOG_ERR,
+                          'Hostname was not updated: Empty not allowed')
+        elif new_hostname == self.hostname:
+            syslog.syslog(syslog.LOG_INFO,
+                          'Hostname was not updated: Already set up with the same name: {}'.format(self.hostname))
+        else:
             syslog.syslog(syslog.LOG_INFO, 'DeviceMetaCfg: Set new hostname: {}'
                                            .format(new_hostname))
             self.hostname = new_hostname
@@ -1367,11 +1373,6 @@ class DeviceMetaCfg(object):
                 return
 
             run_cmd('sudo monit reload')
-        else:
-            msg = 'Hostname was not updated: '
-            msg += 'Already set up' if new_hostname else 'Empty not allowed'
-            syslog.syslog(syslog.LOG_ERR, msg)
-
 
 class MgmtIfaceCfg(object):
     """

tests/hostcfgd/hostcfgd_test.py

@@ -420,6 +420,37 @@ def test_devicemeta_event(self):
             mocked_subprocess.check_call.assert_has_calls(expected,
                                                           any_order=True)
 
+        # Mock empty name
+        HOSTCFG_DAEMON_CFG_DB["DEVICE_METADATA"]["localhost"]["hostname"] = ""
+        original_syslog = hostcfgd.syslog
+        MockConfigDb.set_config_db(HOSTCFG_DAEMON_CFG_DB)
+        with mock.patch('hostcfgd.syslog') as mocked_syslog:
+            mocked_syslog.LOG_ERR = original_syslog.LOG_ERR
+            try:
+                daemon.start()
+            except TimeoutError:
+                pass
+
+            expected = [
+                call(original_syslog.LOG_ERR, 'Hostname was not updated: Empty not allowed')
+            ]
+            mocked_syslog.syslog.assert_has_calls(expected)
+
+        daemon.devmetacfg.hostname = "SameHostName"
+        HOSTCFG_DAEMON_CFG_DB["DEVICE_METADATA"]["localhost"]["hostname"] = daemon.devmetacfg.hostname
+        MockConfigDb.set_config_db(HOSTCFG_DAEMON_CFG_DB)
+        with mock.patch('hostcfgd.syslog') as mocked_syslog:
+            mocked_syslog.LOG_INFO = original_syslog.LOG_INFO
+            try:
+                daemon.start()
+            except TimeoutError:
+                pass
+
+            expected = [
+                call(original_syslog.LOG_INFO, 'Hostname was not updated: Already set up with the same name: SameHostName')
+            ]
+            mocked_syslog.syslog.assert_has_calls(expected)
+
     def test_mgmtiface_event(self):
         """
         Test handling mgmt events.