[Clock] Update system timezone via ConfigDB (#57)

This PR brings functionality that allows us to update the system timezone by writing to the timezone field of the DEVICE_METADATA table of ConfigDB.
The clock CLI implemented in #2793 uses that functionality as the backend.

Signed-off-by: Yevhen Fastiuk <yfastiuk@nvidia.com>

scripts/hostcfgd

@@ -1449,12 +1449,16 @@ class DeviceMetaCfg(object):
 
     def __init__(self):
         self.hostname = ''
+        self.timezone = None
 
     def load(self, dev_meta={}):
         # Get hostname initial
         self.hostname = dev_meta.get('localhost', {}).get('hostname', '')
         syslog.syslog(syslog.LOG_DEBUG, f'Initial hostname: {self.hostname}')
 
+        # Load appropriate config
+        self.timezone = dev_meta.get('localhost', {}).get('timezone')
+
     def hostname_update(self, data):
         """
         Apply hostname handler.
@@ -1485,6 +1489,35 @@ class DeviceMetaCfg(object):
                 return
             run_cmd(['sudo', 'monit', 'reload'])
 
+    def timezone_update(self, data):
+        """
+        Apply timezone handler.
+        Run the following command in Linux: timedatectl set-timezone <timezone>
+        Args:
+            data: Read table's key's data.
+        """
+        new_timezone = data.get('timezone')
+        syslog.syslog(syslog.LOG_DEBUG,
+                      f'DeviceMetaCfg: timezone update to {new_timezone}')
+
+        if new_timezone is None:
+            syslog.syslog(syslog.LOG_DEBUG,
+                          f'DeviceMetaCfg: Recieved empty timezone')
+            return
+
+        if new_timezone == self.timezone:
+            syslog.syslog(syslog.LOG_DEBUG,
+                          f'DeviceMetaCfg: No change in timezone')
+            return
+
+        # run command will print out log error in case of error
+        run_cmd(['timedatectl', 'set-timezone', new_timezone])
+        self.timezone = new_timezone
+
+        run_cmd(['systemctl', 'restart', 'rsyslog'], True, False)
+        syslog.syslog(syslog.LOG_INFO, 'DeviceMetaCfg: Restart rsyslog after '
+                      'changing timezone')
+
 class MgmtIfaceCfg(object):
     """
     MgmtIfaceCfg Config Daemon
@@ -1824,6 +1857,7 @@ class HostConfigDaemon:
     def device_metadata_handler(self, key, op, data):
         syslog.syslog(syslog.LOG_INFO, 'DeviceMeta handler...')
         self.devmetacfg.hostname_update(data)
+        self.devmetacfg.timezone_update(data)
 
     def syslog_handler(self, key, op, data):
         self.syslogcfg.syslog_update(data)

tests/hostcfgd/hostcfgd_test.py

@@ -366,10 +366,15 @@ def test_loopback_update(self):
 class TestHostcfgdDaemon(TestCase):
 
     def setUp(self):
+        self.get_dev_meta = mock.patch(
+            'sonic_py_common.device_info.get_device_runtime_metadata',
+            return_value={'DEVICE_RUNTIME_METADATA': {}})
+        self.get_dev_meta.start()
         MockConfigDb.set_config_db(HOSTCFG_DAEMON_CFG_DB)
 
     def tearDown(self):
         MockConfigDb.CONFIG_DB = {}
+        self.get_dev_meta.stop()
 
     @patchfs
     def test_feature_events(self, fs):
@@ -564,6 +569,7 @@ def test_devicemeta_event(self):
         """
         Test handling DEVICE_METADATA events.
         1) Hostname reload
+        1) Timezone reload
         """
         MockConfigDb.set_config_db(HOSTCFG_DAEMON_CFG_DB)
         MockConfigDb.event_queue = [(swsscommon.CFG_DEVICE_METADATA_TABLE_NAME,
@@ -575,19 +581,16 @@ def test_devicemeta_event(self):
         daemon.load(HOSTCFG_DAEMON_INIT_CFG_DB)
         daemon.register_callbacks()
         with mock.patch('hostcfgd.subprocess') as mocked_subprocess:
-            popen_mock = mock.Mock()
-            attrs = {'communicate.return_value': ('output', 'error')}
-            popen_mock.configure_mock(**attrs)
-            mocked_subprocess.Popen.return_value = popen_mock
-
             try:
                 daemon.start()
             except TimeoutError:
                 pass
 
             expected = [
                 call(['sudo', 'service', 'hostname-config', 'restart']),
-                call(['sudo', 'monit', 'reload'])
+                call(['sudo', 'monit', 'reload']),
+                call(['timedatectl', 'set-timezone', 'Europe/Kyiv']),
+                call(['systemctl', 'restart', 'rsyslog']),
             ]
             mocked_subprocess.check_call.assert_has_calls(expected,
                                                           any_order=True)
@@ -597,31 +600,33 @@ def test_devicemeta_event(self):
         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
+            with mock.patch('hostcfgd.subprocess') as mocked_subprocess:
+                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)
+                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
+            with mock.patch('hostcfgd.subprocess') as mocked_subprocess:
+                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)
+                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):
         """

tests/hostcfgd/test_vectors.py

@@ -1178,7 +1178,8 @@
     "LOOPBACK_INTERFACE": {},
     "DEVICE_METADATA": {
         "localhost": {
-            "hostname": "old-hostname"
+            "hostname": "old-hostname",
+            "timezone": "Etc/UTC"
         }
     },
     "MGMT_INTERFACE": {},
@@ -1247,7 +1248,8 @@
         "localhost": {
             "subtype": "DualToR",
             "type": "ToRRouter",
-            "hostname": "SomeNewHostname"
+            "hostname": "SomeNewHostname",
+            "timezone": "Europe/Kyiv"
         }
     },
     "MGMT_INTERFACE": {