Configure NTP on a GDC VM

This document describes the steps to configure NTP servers on your Google Distributed Cloud (GDC) air-gapped virtual machine (VM).

Systems that rely on event sequencing require consistent clocks for accurate logging and debugging. To standardize time and keep connected systems synchronized, GDC VMs use the Network Time Protocol (NTP) to ensure time accuracy. Without NTP configuration, a VM's clock inevitably drifts, causing timestamp discrepancies that disrupt event sequencing and hinder troubleshooting.

When creating a VM, you can choose between two image sources, both of which include pre configured NTP details:

  • GDC-provided images
  • Bring-your-own (BYO) images

If you import an image with the value prepareImage: false or delete NTP URLs from your VM, you must manually configure NTP using chrony, a tool that actively synchronizes your system clock with external servers. For more information about chrony, see https://chrony-project.org/.

This document is for developers in platform administrator or application operator groups that create VMs using GDC-provided and bring-your-own (byo) images. For more information, see Audiences for GDC air-gapped documentation.

Before you begin

Before you configure NTP servers, verify or install the gdcloud CLI. All Distributed Cloud commands use the gdcloud or kubectl CLI and require an operating system (OS) environment.

  • Check for the CLI: Run gdcloud version

  • If the CLI isn't installed, download and install the gdcloud CLI

Required IAM roles

To get the permissions that you need to configure NTP and manage VM settings, ask your Project IAM Admin to grant you the following IAM roles in the namespace of the project where the VM resides:

  • Project VirtualMachine Admin (project-vm-admin): update VM configurations, modify instance metadata for NTP synchronization, and restart instances to apply system-level changes at the project level

  • Project Viewer (project-viewer): read-only access to inspect VM runtime states, list project resources, and audit configuration settings without the ability to modify project data.

Follow the steps to verify your access.

Configure NTP for your VM

Follow the steps to configure your NTP server details for your specific OS using chrony.

  1. Use ssh to connect to your VM:

    Console

    1. Go to the VM instances page in the GDC console.

    2. Click the SSH button for the instance you want to configure.

    gdcloud

    Use the gdcloud CLI to connect to your VM instance with SSH:

    gcloud compute instances ssh INSTANCE_NAME

    Replace INSTANCE_NAME with the name of your VM instance.

  2. Use the edit command to navigate to your chrony configuration file:

    Ubuntu 

    sudo edit /etc/chrony/chrony.conf

    RHEL 

    sudo edit /etc/chrony.conf

  3. Add the following NTP URLs to your chrony.conf file:

    server ntp1.org.internal iburst
server ntp2.org.internal iburst
server ntp3.org.internal iburst
server ntp4.org.internal iburst
server ntp5.org.internal iburst
server ntp6.org.internal iburst

  4. Restart the chrony service:

    Ubuntu 

    sudo systemctl restart chrony

    RHEL 

    sudo systemctl restart chronyd

  5. Verify your configuration using the chrony CLI:

    chronyc sources -v

    The output looks similar to the following:

    210 Number of sources = 1
MS Name/IP address         Stratum Poll Reach LastRx Last sample
===============================================================================
^* metadata.google.internal      2   7   377    98  -1343ns[-1588ns] +/-  396us

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