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Version: 1.4

NTP configuration with Elemental​

Overview​

The default OS channel shipped with Elemental provides NTP support via systemd-timesyncd.

This page covers configuring systemd-timesyncd with the provided SLE Micro images, which is pre-configured with some default (fallback) NTP servers: ([0-3].suse.pool.ntp.org).

The easiest way to configure a specific NTP server, is to drop a configuration file in the /etc/systemd/timesyncd.conf.d directory. The directory and the configuration file should be accessible by the systemd-timesync user.

Configure a static NTP server​

The NTP configuration can be provided via a cloud-config snippet added to the MachineRegistration configuration.

We will need to:

  • ensure the timesyncd.conf.d directory can be read by the systemd-timesync user
  • write the custom config file in the timesyncd.conf.d directory
  • restart the systemd-timesyncd service to use the new configuration

As an example, let's see how to configure ntp.ripe.net as the primary NTP server (lines 6-14):

config:
cloud-config:
users:
- name: root
passwd: root
write_files:
- content: |
[Time]
NTP=ntp.ripe.net
path: /etc/systemd/timesyncd.conf.d/custom-ntp.conf
permissions: 644
runcmd:
- chmod 755 /etc/systemd/timesyncd.conf.d
- systemctl restart systemd-timesyncd
elemental:
install:
device: /dev/vda
reboot: true
machineInventoryLabels:
element: fire

Configure NTP from DHCP​

In order to get the NTP server from the network via the NTP DHCP option, we need a NetworkManager dispatcher script to reconfigure dynamically the systemd-timesync service when needed.

We will have both to:

  • provide the dispatcher script which creates and deletes the systemd-timesyncd config files
  • enable the NetworkManager-dispatcher service

See lines 6-34 in the following MachineRegistration configuration example:

config:
cloud-config:
users:
- name: root
passwd: root
write_files:
- content: |
#! /usr/bin/bash

[ -n "$CONNECTION_UUID" ] || exit

INTERFACE=$1
ACTION=$2

case $ACTION in
up | dhcp4-change | dhcp6-change)
[ -n "$DHCP4_NTP_SERVERS" ] || exit
mkdir -p /etc/systemd/timesyncd.conf.d/
cat<<EOF > /etc/systemd/timesyncd.conf.d/$CONNECTION_UUID.conf
[Time]
NTP=$DHCP4_NTP_SERVERS
RootDistanceMaxSec=15
EOF
systemctl restart systemd-timesyncd
;;
down)
rm -f /etc/systemd/timesyncd.conf.d/$CONNECTION_UUID.conf
systemctl restart systemd-timesyncd
;;
esac
path: /etc/NetworkManager/dispatcher.d/10-update-timesyncd
permissions: 700
runcmd:
- systemctl enable NetworkManager-dispatcher
elemental:
install:
device: /dev/vda
reboot: true
machineInventoryLabels:
element: fire