Monitor DNS_OPTIONS for changes (sonic-net#239)

Author: bhouse-nexthop

scripts/hostcfgd

@@ -2230,6 +2230,7 @@ class HostConfigDaemon:
         syslog_cfg = init_data.get(swsscommon.CFG_SYSLOG_CONFIG_TABLE_NAME, {})
         syslog_srv = init_data.get(swsscommon.CFG_SYSLOG_SERVER_TABLE_NAME, {})
         dns = init_data.get('DNS_NAMESERVER', {})
+        dns_options = init_data.get('DNS_OPTIONS', {})
         fips_cfg = init_data.get('FIPS', {})
         ntp_global = init_data.get(swsscommon.CFG_NTP_GLOBAL_TABLE_NAME)
         ntp_servers = init_data.get(swsscommon.CFG_NTP_SERVER_TABLE_NAME)
@@ -2246,7 +2247,7 @@ class HostConfigDaemon:
         self.devmetacfg.load(dev_meta)
         self.mgmtifacecfg.load(mgmt_ifc, mgmt_vrf)
         self.rsyslogcfg.load(syslog_cfg, syslog_srv)
-        self.dnscfg.load(dns)
+        self.dnscfg.load(dns, dns_options)
         self.fipscfg.load(fips_cfg)
         self.ntpcfg.load(ntp_global, ntp_servers, ntp_keys)
         self.serialconscfg.load(serial_console)
@@ -2405,6 +2406,10 @@ class HostConfigDaemon:
         syslog.syslog(syslog.LOG_INFO, 'DNS nameserver handler...')
         self.dnscfg.dns_update(key, data)
 
+    def dns_options_handler(self, key, op, data):
+        syslog.syslog(syslog.LOG_INFO, 'DNS options handler...')
+        self.dnscfg.dns_update(key, data)
+
     def fips_config_handler(self, key, op, data):
         syslog.syslog(syslog.LOG_INFO, 'FIPS table handler...')
         data = self.config_db.get_table("FIPS")
@@ -2478,6 +2483,7 @@ class HostConfigDaemon:
                                  make_callback(self.rsyslog_server_handler))
 
         self.config_db.subscribe('DNS_NAMESERVER', make_callback(self.dns_nameserver_handler))
+        self.config_db.subscribe('DNS_OPTIONS', make_callback(self.dns_options_handler))
 
         # Handle FIPS changes
         self.config_db.subscribe('FIPS', make_callback(self.fips_config_handler))

tests/hostcfgd/hostcfgd_test.py

@@ -429,6 +429,17 @@ def test_dns_events(self):
                 pass
             mocked_run_cmd.assert_has_calls([call(['systemctl', 'restart', 'resolv-config'], True, False)])
 
+    def test_dns_options_events(self):
+        MockConfigDb.set_config_db(HOSTCFG_DAEMON_CFG_DB)
+        MockConfigDb.event_queue = [('DNS_OPTIONS', 'ndots')]
+        daemon = hostcfgd.HostConfigDaemon()
+        daemon.register_callbacks()
+        with mock.patch('hostcfgd.run_cmd') as mocked_run_cmd:
+            try:
+                daemon.start()
+            except TimeoutError:
+                pass
+            mocked_run_cmd.assert_has_calls([call(['systemctl', 'restart', 'resolv-config'], True, False)])
 
 class TestDnsHandler:
 

tests/hostcfgd/test_vectors.py

@@ -29,7 +29,8 @@
     "MGMT_VRF_CONFIG": {},
     "SYSLOG_CONFIG": {},
     "SYSLOG_SERVER": {},
-    "DNS_NAMESERVER": {}
+    "DNS_NAMESERVER": {},
+    "DNS_OPTIONS": {}
 }
 
 
@@ -98,4 +99,7 @@
     "DNS_NAMESERVER": {
         "1.1.1.1": {}
     },
+    "DNS_OPTIONS": {
+        "ndots": "4"
+    }
 }