timezone issue for scheduler

[qli-aa]

sample code from apscheduler docs:

from pytz import utc
....
scheduler = BackgroundScheduler(jobstores=jobstores, executors=executors, job_defaults=job_defaults, timezone=utc)

it works for ubuntu, but after I change OS to amazonlinux, does not work
error message:

ERROR:apscheduler.jobstores.default:Unable to restore job "xxxx_job" -- removing it
Traceback (most recent call last):
  File "/usr/local/lib64/python2.7/site-packages/apscheduler/jobstores/sqlalchemy.py", line 141, in _get_jobs
    jobs.append(self._reconstitute_job(row.job_state))
  File "/usr/local/lib64/python2.7/site-packages/apscheduler/jobstores/sqlalchemy.py", line 125, in _reconstitute_job
    job_state = pickle.loads(job_state)
  File "/usr/local/lib/python2.7/site-packages/pytz/__init__.py", line 283, in _p
    return unpickler(*args)
  File "/usr/local/lib/python2.7/site-packages/pytz/tzinfo.py", line 539, in unpickler
    tz = pytz.timezone(zone)
  File "/usr/local/lib/python2.7/site-packages/pytz/__init__.py", line 177, in timezone
    raise UnknownTimeZoneError(zone)
UnknownTimeZoneError: 'local'

then I add a file /etc/timezone with content 'Etc/UTC', it works

when add a scheduled job, should it use timezone I passed in code otherwise read from /etc/timezone ?
looks like it always get it from system config

[qli-aa]

I found 2 issues here:

1. apscheduler does not use timezone keyword I passed ?
2. pytz/tzlocal try to get timezone function had a bug with amazonlinux distribution issue

[agronholm]

1. How did you pass the timezone argument?
2. Where should tzlocal find the local timezone on amazonlinux?

[qli-aa]

pass timezone=utc to BackgroundScheduler like this:

from pytz import utc
scheduler = BackgroundScheduler(jobstores=jobstores, executors=executors, job_defaults=job_defaults, timezone=utc)

2. amazonlinux should be /etc/localtime, like centos/redhat instead of /etc/timezone, but tzlocal think it was not centos-like OS (because /etc/localtime exists but not a symlink), then return local timezone

[agronholm]

amazonlinux should be /etc/localtime, like centos/redhat instead of /etc/timezone, but tzlocal think it was not centos-like OS (because /etc/localtime exists but not a symlink), then return local timezone

Didn't you just say that you had to create /etc/timezone yourself?

[qli-aa]

yes. I created /etc/timezone as a workaround solution
#2 is not because of apscheduler, I'm just wondering why the time param does not effect I passed

[agronholm]

For 1), lots of people use an explicit time zone and it works fine for them. Would you mind giving me a complete, minimal standalone script that demonstrates the problem?
For 2), if /etc/timezone is not there, does it at least have /etc/localtime or another source of timezone information?

[bngo92]

This is the issue I'm seeing with APScheduler-3.0.5 on CentOS Linux release 7.4.1708 (Core)

Traceback (most recent call last):
  File "apscheduler/schedulers/base.py", line 334, in add_job
    'trigger': self._create_trigger(trigger, trigger_args),
  File "apscheduler/schedulers/base.py", line 787, in _create_trigger
    return self._create_plugin_instance('trigger', trigger, trigger_args)
  File "apscheduler/schedulers/base.py", line 773, in _create_plugin_instance
    return plugin_cls(**constructor_kwargs)
  File "apscheduler/triggers/cron/__init__.py", line 52, in __init__
    self.timezone = astimezone(timezone)
  File "apscheduler/util.py", line 80, in astimezone
    raise ValueError('Unable to determine the name of the local timezone -- use an explicit timezone instead')
ValueError: Unable to determine the name of the local timezone -- use an explicit timezone instead

/etc/localtime does say UTC but since the zone is always local when using /etc/localtime, APScheduler doesn't work.

TZif2UTCTZif2UTC
UTC0

[agronholm]

@bngo92 Does this happen with the latest versions of tzlocal and apscheduler?

[likewhoa]

@bngo92 You need to use a timezone name (such as Europe/Helsinki). For me it was America/New_York. echo "America/New_York >/etc/timezone for instance.

[agronholm]

As for the first observed problem, it happened while restoring an existing job. The timezone you set for the scheduler does not affect jobs added before that. So, not a bug. As for the second, report that to the tzlocal issue tracker.