How to make temporary changes to the NTP settings with VKS without triggering Guest Cluster Rolling Update

Products

• VMware vSphere Kubernetes Service

Issue/Introduction

With vSphere 8U3, when you update NTP settings of the Supervisor in the vCenter UI it triggers a rolling update on Guest Clusters.
In contrast, the change takes effect immediately on the Supervisor Cluster, without any rolling update.

• Change the Management Network Settings on a Supervisor
  • vCenter UI -> Supervisor -> Config -> Network ->  Management Network -> NTP

In large-scale environments, administrators may prefer to update the NTP server without initiating rolling updates across Guest Clusters. This KB outlines a method to temporarily change the NTP server without triggering rolling updates on the Guest Clusters.

Note: This is a temporary workaround. A full rolling update should be carried out at a later, appropriate time to ensure persistent change.

Environment

VMware vSphere Kubernetes Service - vCenter 8U3

Resolution

Change the NTP server temporarily for Supervisor

1. SSH login to the supervisor

• How to SSH to the Supervisor
• Do not use FIP, SSH to the Supervisor by using the individual IP address

2. Edit /etc/systemd/timesyncd.conf

vi /etc/systemd/timesyncd.conf

[Time]
NTP=<NTP_SERVER_IPADDRESS_1> <NTP_SERVER_IPADDRESS_2>

3. Restart systemd-timesyncd

systemctl restart systemd-timesyncd
systemctl status systemd-timesyncd

4. Check the result

timedatectl status
timedatectl timesync-status
timedatectl show-timesync --all

5. Repeat this operation for the remaining 2 Supervisors.

 

Change the NTP server temporarily for Guest Cluster - PhotonOS

1. SSH login to the Guest Cluster node

• SSH to TKG Service Cluster Nodes as the System User Using a Password

2. Check the current NTP setting

sudo -i
chronyc sources -v

3. Update NTP server configuration

vi /etc/chrony.conf
  
server <NTP_SERVER_IPADDRESS_1> iburst
server <NTP_SERVER_IPADDRESS_2> iburst

4. Restart chronyd

systemctl restart chronyd
systemctl status chronyd

5. Check the result

chronyc sources -v

6. Repeat this operation for all remaining Kubernetes nodes.

Additional Information

KB-389998 - How to change NTP Server settings for Guest Clusters(VKC) on Supervisor when NSX-T is backend network