Display timestamps in local time zone, respecting TZ environment variable

[realsobek]

dnf-4.23.0-1.fc40.noarch uses local time timestamps (at the moment +0200 due to summer time) in dnf history and /var/log/dnf.log.
dnf5-5.2.12.0-2.fc42.x86_64 uses UTC time timestamps in dnf history and /var/log/dnf5.log. In example below you see the 2 hour difference. The difference makes it harder to trace actions, because all other apps' logs and timestamps use local time.
Because RPM scriptlet action's output gets truncated I grep /var/log/dnf.log after automated system installation is done.

I cannot find an option to force dnf5 to use local time. Is there no such option? Something like dnf history list --uselocaltime would be handy.

I found an issue was created for upstream tests #900 reply:

It's normal that time formatting functions and thus applications honor a localtime zone.

In rpm-software-management/ci-dnf-stack#1386 the same issue got reply:

This got changed in #844 when the Issued time was unified with the rest of dates printed by dnf5 (like in repo info or history list). The times are now always in UTC.

I do not know the big picture: brainstorming: Add dnf5 option to force UTC time output? Update the upstream tests to cope with local time?
If no change is intended, please, add a note to https://dnf5.readthedocs.io/en/stable/changes_from_dnf4.7.html that dnf5 output is unified on UTC.

Example with Fedora 42 and dnf5:

# timedatectl
               Local time: Wed 2025-04-16 13:40:20 CEST
           Universal time: Wed 2025-04-16 11:40:20 UTC
                 RTC time: Wed 2025-04-16 11:40:20
                Time zone: Europe/Berlin (CEST, +0200)
System clock synchronized: yes
              NTP service: active
          RTC in local TZ: no
# date
Wed Apr 16 01:40:18 PM CEST 2025
# dnf install -y leafpad
...
# dnf history list
 ID Command line                        Date and time       Action(s) Altered
255 dnf install -y leafpad              2025-04-16 11:40:28                 1
...
# vim /var/log/dnf5.log
...
2025-04-16T11:40:25+0000 [8393] INFO --- DNF5 launched with arguments: "dnf install -y leafpad" ---
...

Kudos for the timestamp formatting:
2025-04-16T11:40:25
I like it much better than journalctl's output:
Apr 16 13:40:50

[ppisar]

In my opinion, dnf5 should print all times in the local time zone. I.e. your option would be TZ variable.

I believe that the referred change was just a quick fix to get all time stamps alike.

I will bring this topic to DNF team meating.

[realsobek]

Thank you. Take your time.

At the moment the TZ variable is not honored by dnf5 on Fedora 42 (other apps, like date do; I use bash shell), i.e. both commands print UTC timestamp:

# TZ='Asia/Kolkata' dnf history list --contains-pkgs leafpad | head -2
# export TZ='Europe/Berlin' ; dnf history list --contains-pkgs leafpad | head -2

[ppisar]

DNF team discussed this issue and concluded that:

• Time stamps displayed in the user interface should be in local time zone.
• Time stamps written in logs should be in UTC.

All time stamps should be formatted with a time offset indicator, UTC offset abbreviated as "Z".

[ppisar]

Fedora bug report: https://bugzilla.redhat.com/show_bug.cgi?id=2316624