[config]: Add hostname command to config CLI

config/main.py

@@ -524,6 +524,25 @@ def load_minigraph():
     click.echo("Please note setting loaded from minigraph will be lost after system reboot. To preserve setting, run `config save`.")
 
 
+#
+# 'change-hostname' command
+#
+@config.command('change-hostname')
+@click.argument('hostname', metavar='<hostname>', required=True)
+def change_hostname(hostname):
+    """Change Hostname on a SONiC device without impacting the traffic."""
+
+    config_db = ConfigDBConnector()
+    config_db.connect()
+    config_db.mod_entry('DEVICE_METADATA' , 'localhost', {"hostname" : hostname})
+    try:
+        command = "service hostname-config restart"
+        run_command(command, display_cmd=True)
+    except SystemExit as e:
+        click.echo("Restarting hostname-config  service failed with error {}".format(e))
+        raise
+    click.echo("Please note loaded setting will be lost after system reboot. To preserve setting, run `config save`.")
+
 #
 # 'portchannel' group ('config portchannel ...')
 #

doc/Command-Reference.md

@@ -220,6 +220,7 @@ This command lists all the possible configuration commands at the top level.
     aaa                    AAA command line
     acl                    ACL-related configuration tasks
     bgp                    BGP-related configuration tasks
+    change-hostname        Change Hostname on a SONiC device without...
     ecn                    ECN-related configuration tasks
     interface              Interface-related configuration tasks
     interface_naming_mode  Modify interface naming mode for interacting...
@@ -1560,6 +1561,28 @@ This command is used to remove particular IPv4 or IPv6 BGP neighbor configuratio
 
 Go Back To [Beginning of the document](#SONiC-COMMAND-LINE-INTERFACE-GUIDE) or [Beginning of this section](#BGP-Configuration-And-Show-Commands)
 
+# Update Hostname Configuration Commands
+
+This sub-section of commands is used to change the hostname on a SONiC device without traffic being impacted.
+
+**config change-hostname <hostname>**
+This command is used to change the hostname on a SONiC device without traffic being impacted.
+- Usage: config change-hostname [OPTIONS] <hostname>
+
+        Change Hostname on a SONiC device without impacting the traffic.
+
+        Options:
+          --help  Show this message and exit.
+- Examples:
+  ```
+  admin@csw06:~$ sudo config change-hostname csw06-sonic
+  Running command: service hostname-config restart
+  Please note loaded setting will be lost after system reboot. To preserve setting, run config save.
+
+
+  admin@csw06:~$ sudo config save -y
+  Running command: /usr/local/bin/sonic-cfggen -d --print-data > /etc/sonic/config_db.json
+  ```
 
 # ECN Configuration And Show Commands