changing timezones only works partially on linux 24.04

[emaayan]

i don't know exactly if this is a bug report or not.. but we've noticed that in ubuntu 24 changing the time zone doesn't seem to take effect in all places
for example doing timedatectl set-timezone don't seem to touch /etc/timezone which is what java takes it's values from by default in ubuntu it seems that dpkg-reconfigure tzdata is considered the standard way of doing things but i understand you guys are using dbus and systemd api's which means this wont' get affected.

[martinpitt]

Indeed Debian carried a systemd patch to update /etc/timezone for many years (I was even part of that), but it was removed last year: https://salsa.debian.org/systemd-team/systemd/-/commit/5d4b34101117b9b9e64ecbc9b602113f91d4e837

"tzdata will no longer create it, we can just rely on /etc/localtime". Does it actually work to just remove it from your system? (Move it away so that you can restore it easily if it breaks Java)

[emaayan]

what do you mean remove it? try to completely remove /etc/timezone and where java will try and take timezone info? won't that brake other stuff in ubuntu?

[martinpitt]

I'm no expert here, but Debian plans to remove /etc/timezone, see https://bugs.debian.org/822733. It was restored later on in https://tracker.debian.org/news/1421751/accepted-tzdata-2022g-6-source-into-unstable/ and the migration postponed to Debian 13. Hence I suggested trying what happens if you move it away now, if Java falls back to /etc/localtime. Fedora and RHEL haven't had /etc/timezone for many many years, and Java is definitively a thing for RHEL. So there's a good chance that it actually works.

We will not change anything here in Cockpit -- either /etc/timezone is obsolete, and then the distributions will clean it up eventually (that seems to be the current plan); or it isn't, then that systemd patch should be restored.

[emaayan]

thanks, will try that , i have some back plan to try this as well, but i'm not sure if there are any "hooks" scripts that are triggered when someone changes a timezone, plus i have to figure why there are conflicts between cockpit-bridge and cockpit-pcp too (according to apt at least, but that's another story) timedatectl show --property=Timezone --value | sudo tee /etc/timezone

/dev/null

sudo dpkg-reconfigure --frontend noninteractive tzdata

…

On Thu, Nov 28, 2024 at 10:30 AM Martin Pitt ***@***.***> wrote: I'm no expert here, but Debian plans to remove /etc/timezone, see https://bugs.debian.org/822733. It was restored later on in https://tracker.debian.org/news/1421751/accepted-tzdata-2022g-6-source-into-unstable/ and the migration postponed to Debian 13. Hence I suggested trying what happens if you move it away now, if Java falls back to /etc/localtime. Fedora and RHEL haven't had /etc/timezone for many many years, and Java is definitively a thing for RHEL. So there's a good chance that it actually works. We will not change anything here in Cockpit -- either /etc/timezone is obsolete, and then the distributions will clean it up eventually (that seems to be the current plan); or it isn't, then that systemd patch should be restored. — Reply to this email directly, view it on GitHub <#21336 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADGP5MAWJQEIEOO5DT7RCML2C3ICXAVCNFSM6AAAAABSQY7DFCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKMBVGUZDQMJRGM> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[martinpitt]

cockpit-pcp is obsolete, an upgrade should remove it (it got absorbed into cockpit-bridge)

[emaayan]

I'm no expert here, but Debian plans to remove /etc/timezone, see bugs.debian.org/822733. It was restored later on in tracker.debian.org/news/1421751/accepted-tzdata-2022g-6-source-into-unstable and the migration postponed to Debian 13. Hence I suggested trying what happens if you move it away now, if Java falls back to /etc/localtime. Fedora and RHEL haven't had /etc/timezone for many many years, and Java is definitively a thing for RHEL. So there's a good chance that it actually works.

We will not change anything here in Cockpit -- either /etc/timezone is obsolete, and then the distributions will clean it up eventually (that seems to be the current plan); or it isn't, then that systemd patch should be restored.

that seems to work too, but won't updating tzdata will automatically create this file? or do i need to remove tzdata too?

[martinpitt]

won't updating tzdata will automatically create this file

Right, this was just a test, not a permanent solution for Ubuntu 22.04. I was mostly wondering if Java still needs /etc/timezone somehow (which would be a surprise, but you never know..)

do i need to remove tzdata too?

Ugh no, this is very important. It's just /etc/timezone which is obsolete; /etc/localtime symlink and the actual time zone data continue to be (very) relevant.

Thanks for checking!

[martinpitt]

not a permanent solution for Ubuntu 22.04

Sorry, you said 24.04, but same difference really -- Debian 13 will drop it, and some Ubuntu 25.XX or 26.XX will eventually inherit it.

[emaayan]

so basically i need to make sure /etc/timezone gets removed every time i start my java service