Bug#947936: chrony: Does (still) not start properly on boot on buster

[Vincent Blut]

Hi Santiago,

On 2020-01-02T13:38+0100, Santiago Vila wrote:

Package: chrony
Version: 3.4-4
Severity: important

Dear maintainer:

Apparently, installing chrony does not ensure at all that it will work.

Google has moved from ntp in Debian 9 to chrony in Debian 10 for their
default Debian GCE images, and I discovered this on a lot of GCE
instances having a clock several minutes off.

The problem I found is very similar to the one described here:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=933370

Indeed, it sounds pretty similar.

I believe the best summary of the problem was made by Michael Biebl
here:

https://github.com/systemd/systemd/issues/7104#issuecomment-471329392

Quoting Michael:

As it stands, the current practice of having systemd-timesyncd.service
enabled by default (in Debian) and alternative implementations like
chrony or ntpd declare Conflicts=systemd-timesyncd.service in their
service file does not work reliably.

AFAIK, this has been fixed on the systemd side in version 241-3 by
dropping the "Conflicts" systemd had on chrony or ntpd.

$ cat 
/lib/systemd/system/systemd-timesyncd.service.d/disable-with-time-daemon.conf
[Unit]
ConditionFileIsExecutable=!/usr/sbin/ntpd
ConditionFileIsExecutable=!/usr/sbin/openntpd
ConditionFileIsExecutable=!/usr/sbin/chronyd
ConditionFileIsExecutable=!/usr/sbin/VBoxService

It prevents systemd-timesyncd from starting if one of the above
executables is present on the system.

Exact, the Debian systemd maintainers reintroduced the following drop-in file in version 241-3:

Unfortunately, AFAIK, conflicts are bi-directional, so apparently the
problem will persist in buster as far as chrony still has conflicts
in the systemd unit file.

What do you mean by “conflicts are bi-directional”?

Also, conflicting with systemd-timesyncd doesn’t seem to cause any issue on most systems (well, I hope ;-), so we should be cautious about incriminating “Conflicts= systemd-timesyncd.service” use as the root cause. Would you please tell me how things go when removing “ConditionFileIsExecutable=!/usr/sbin/chronyd” from the systemd-timesyncd service unit? Does that make chrony happy?

Thanks.

Cheers,
Vincent

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