config-custom-ntp.md

copyright	lastupdated	keywords	subcollection
years 2022, 2024	2024-01-03	satellite, hybrid, multicloud, ntp, custom ntp, network time protocol	satellite

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Specifying a custom Network Time Protocol (NTP) server

{: #config-custom-ntp}

Keeping time is an integral part of any system. You can choose to allow access to the Red Hat network time protocol (NTP) servers or you can configure access to a custom Network Time Protocol (NTP) server. {: shortdesc}

You can specify a custom NTP server for Red Hat CoreOS hosts only. {: note}

Specifying a custom NTP server for an unattached host

{: #custom-ntp-config}

To configure your hosts to use a custom NTP server before you attach them to a location, edit the host script to include your custom NTP server information. This example uses a chrony NTP server.

1. Create a chrony.conf file similar to the following example.

   pool time.adn.networklayer.com iburst
   
   server time.adn.networklayer.com iburst minpoll 3 maxpoll 4
   
   # Record the rate at which the system clock gains/losses time.
   driftfile /var/lib/chrony/drift
   
   # Allow the system clock to be stepped in the first three updates
   # if its offset is larger than 1 second.
   makestep 1.0 3
   
   # Enable kernel synchronization of the real-time clock (RTC).
   rtcsync
   
   # Specify file containing keys for NTP authentication.
   keyfile /etc/chrony.keys
   
   # Get TAI-UTC offset and leap seconds from the system tz database.
   leapsectz right/UTC
   
   # Specify directory for log files.
   logdir /var/log/chrony

   {: codeblock}

2. Convert the content to base64.

   cat chrony.conf | base64

   {: pre}

3. Download the attach script for your location. For RHCOS hosts, the attach script is an ignition (.ign) script.

   ibmcloud sat host attach --location LOCATION --operating-system RHCOS

   {: pre}

4. Edit the script and add an entry to the storage.files array, where BASE64_ENCODED_CHRONY_FILE_DATA is the base 64 string from step 2.

   {
     "overwrite": true,
     "path": "/etc/chrony.conf",
     "contents": {
       "source":"data:text/plain;base64,BASE64_ENCODED_CHRONY_FILE_DATA"
       },
       "mode": 420
    }

   {: codeblock}

5. Save the script.

6. Validate the script.

   cat IGNITION_FILE_PATH | jq -r

   {: pre}

After your script is validated, you can attach the hosts to your location.

Specifying a custom NTP for an attached host

{: #custom-ntp-attached-host}

You can configure a custom NTP server for your hosts after they are attached to the location. {: shortdesc}

1. Create a chrony.conf file similar to the following example.

   pool time.adn.networklayer.com iburst
   
   server time.adn.networklayer.com iburst minpoll 3 maxpoll 4
   
   # Record the rate at which the system clock gains/losses time.
   driftfile /var/lib/chrony/drift
   
   # Allow the system clock to be stepped in the first three updates
   # if its offset is larger than 1 second.
   makestep 1.0 3
   
   # Enable kernel synchronization of the real-time clock (RTC).
   rtcsync
   
   # Specify file containing keys for NTP authentication.
   keyfile /etc/chrony.keys
   
   # Get TAI-UTC offset and leap seconds from the system tz database.
   leapsectz right/UTC
   
   # Specify directory for log files.
   logdir /var/log/chrony

   {: codeblock}

2. Log in to the host system.

3. Update the chrony.conf file for that host, where CHRONY_FILE_DATA is the name of the file you created in step 1. Do not convert this file into base64.

   cat >"/etc/chrony.conf" <<EOF
   CHRONY_FILE_DATA
   EOF
   systemctl restart chronyd

   {: pre}

After you update the chrony.conf file, your host uses your custom NTP server.