[config] Reload Monit configuration after potential hostname changes (s…

…onic-net#1132)

**- What I did**

After hostname changes, we need to reload the Monit configuration in order for Monit to pick up the new system hostname. Otherwise, it will retain the previous hostname.

**- How I did it**

Call `sudo monit reload` after restarting hostname-config.service.

config/main.py

@@ -751,6 +751,10 @@ def _restart_services(config_db):
 
     execute_systemctl(services_to_restart, SYSTEMCTL_ACTION_RESTART)
 
+    # Reload Monit configuration to pick up new hostname in case it changed
+    click.echo("Reloading Monit configuration ...")
+    clicommon.run_command("sudo monit reload")
+
 
 def interface_is_in_vlan(vlan_member_table, interface_name):
     """ Check if an interface  is in a vlan """
@@ -1235,6 +1239,11 @@ def hostname(new_hostname):
     except SystemExit as e:
         click.echo("Restarting hostname-config  service failed with error {}".format(e))
         raise
+
+    # Reload Monit configuration to pick up new hostname in case it changed
+    click.echo("Reloading Monit configuration ...")
+    clicommon.run_command("sudo monit reload")
+
     click.echo("Please note loaded setting will be lost after system reboot. To preserve setting, run `config save`.")
 
 #

tests/config_test.py

@@ -43,6 +43,7 @@
 Executing restart of service hostcfgd...
 Executing restart of service nat...
 Executing restart of service telemetry...
+Reloading Monit configuration ...
 Please note setting loaded from minigraph will be lost after system reboot. To preserve setting, run `config save`.
 """