netFIELD App Edge Monitor does not work on Fedora 35 due to missing /etc/timezone

Q

A

Description and identification

netFIELD App Edge Monitor container crashes some seconds after start, stuck in a restart loop
- does not publish any messages to the MQTT broker
- related log records written by the container
  - Traceback (most recent call last):
    File "index.py", line 370, in <module>
    scheduler.add_job(
    File "/root/.local/lib/python3.8/site-packages/apscheduler/schedulers/base.py", line 420, in add_job
    'trigger': self._create_trigger(trigger, trigger_args),
    File "/root/.local/lib/python3.8/site-packages/apscheduler/schedulers/base.py", line 921, in _create_trigger
    return self._create_plugin_instance('trigger', trigger, trigger_args)
    File "/root/.local/lib/python3.8/site-packages/apscheduler/schedulers/base.py", line 906, in _create_plugin_instance
    return plugin_cls(**constructor_kwargs)
    File "/root/.local/lib/python3.8/site-packages/apscheduler/triggers/interval.py", line 38, in __init__
    self.timezone = astimezone(timezone)
    File "/root/.local/lib/python3.8/site-packages/apscheduler/util.py", line 86, in astimezone
    raise ValueError(
    ValueError: Unable to determine the name of the local timezone -- you must explicitly specify the name of the local timezone. Please refrain from using timezones like EST to prevent problems with daylight saving time. Instead, use a locale based timezone name
    (such as Europe/Helsinki).

Analysis

The netFIELD App Edge Monitor application retrieves the timezone from the /etc/timezone file. The create options include a bind mount "/etc/timezone:/etc/timezone" to share the configured host timezone with the container.

Fedora 35 does not use /etc/timezone to store the configured timezone, the file does not even exist. The timezone info is available following the symlink /etc/localtime is pointing to.

[iot-test@tst-nfexts-6953-fedora35 ~]$ ls -lh /etc/timezone

ls: cannot access '/etc/timezone': No such file or directory

[iot-test@tst-nfexts-6953-fedora35 ~]$ ls -lh /etc/localtime

lrwxrwxrwx. 1 root root 35 Apr 5 08:27 /etc/localtime -> ../usr/share/zoneinfo/Europe/Berlin

Workaround

Generate a /etc/timezone file reflecting the currently set timezone:

this will not be automatically updated when changing the timezone, "snapshots" the currently set timezone and writes it to /etc/timezone

sudo rm -rf /etc/timezone; timedatectl show | grep Timezone | awk -F '=' '{print $2}' | sudo tee /etc/timezone

note: due to the bind-mount used by netFIELD App Edge Monitor, there will be an auto-created directory /etc/timezone/ after deploying the container

example result:

[iot-test@tst-nfexts-6953-fedora35 ~]$ cat /etc/timezone
Europe/Berlin
[iot-test@tst-nfexts-6953-fedora35 ~]$ ls -lh /etc/localtime
lrwxrwxrwx. 1 root root 35 Apr  5 08:27 /etc/localtime -> ../usr/share/zoneinfo/Europe/Berlin

See also...