NTP time sources ignored by chrony in Ubuntu 26.04 LTS

Ubuntu 26.04 runs chrony as it’s default time sync. service. This is nice, but the way they have configured it has a gotcha.

The default sources are defined in /etc/chrony/sources.d/ubuntu-ntp-pools.sources. The default contents of this file are:

# Use NTS by default
# NTS uses an additional port to negotiate security: 4460/tcp
# The normal NTP port remains in use: 123/udp
pool 1.ntp.ubuntu.com iburst maxsources 1 nts prefer
pool 2.ntp.ubuntu.com iburst maxsources 1 nts prefer
pool 3.ntp.ubuntu.com iburst maxsources 1 nts prefer
pool 4.ntp.ubuntu.com iburst maxsources 1 nts prefer
# The bootstrap server is needed by systems without a hardware clock, or a very
# large initial clock offset. The specified certificate set is defined in
# /etc/chrony/conf.d/ubuntu-nts.conf.
pool ntp-bootstrap.ubuntu.com iburst maxsources 1 nts certset 1

# If you can't or won't use NTS, then here are the old NTP-only definitions

# This will use (up to):
# - 4 sources from ntp.ubuntu.com which some are ipv6 enabled
# - 2 sources from 2.ubuntu.pool.ntp.org which is ipv6 enabled as well
# - 1 source from [01].ubuntu.pool.ntp.org each (ipv4 only atm)
# This means by default, up to 6 dual-stack and up to 2 additional IPv4-only
# sources will be used.
# At the same time it retains some protection against one of the entries being
# down (compare to just using one of the lines). See (LP: #1754358) for the
# discussion.
#
# About using servers from the NTP Pool Project in general see (LP: #104525).
# Approved by Ubuntu Technical Board on 2011-02-08.
# See http://www.pool.ntp.org/join.html for more information.
#pool ntp.ubuntu.com        iburst maxsources 4
#pool 0.ubuntu.pool.ntp.org iburst maxsources 1
#pool 1.ubuntu.pool.ntp.org iburst maxsources 1
#pool 2.ubuntu.pool.ntp.org iburst maxsources 2

We use local campus time sources, and added them in a separate .sources file. After reloading the sources and checking with

Stop X windows using GPU

We have some servers that have a GPU (or several) for computational purposes. The servers have an integrated display device (usually ASPEED or similar). We often have graphical desktops installed, as we want remote desktop access to run CAD programs etc.

This can lead to issues. For example, if we have a server with a NVIDIA RTX A5000 and it’s own motherboard display, you can install Rocky 8 or 9 (but not 10, as it’s Wayland only and you want to use xrdp). If it doesn’t install the nvidia drivers by default then on reboot the standard gdm launcher pops up on the onboard display and you can log into it. When the Nvidia repository is set up and the standard Nvidia drivers are installed a reboot shows the boot sequence at the start, then disappears. The issue is that the graphical launcher is displaying on the GPU instead, which we don’t want.

Upgrade gitlab 18 to 19 - mattermost deprecation causing failure.

In version 19 of GitLab mattermost has been removed from the omnibus package. The upgrade process checks for mattermost configuration directives and aborts if any are found. Unfortunately these can take some weeding out - particularly when using the https://packages.gitlab.com/gitlab/gitlab-ee apt repository.

Our specific case:

• Debian 12/13
• GitLab omnibus ee installed using apt package
• Mattermost not running and never configured

To upgrade:

Do usual checks and backups beforehand.

Check all mattermost configuration options in /etc/gitlab/gitlab.rb are commented out or removed. If they are removed then it is easy to check with grep that nothing has been missed.