Crash at startup

[jvoisin]

Describe the bug/problem

Calibre-web is crashing on startup.

To Reproduce
Steps to reproduce the behavior:

1. python3 /opt/calibre/cps.py
2. get a crash

Logfile

/opt/calibre $ python3 /opt/calibre/cps.py
Traceback (most recent call last):
  File "/opt/calibre/cps.py", line 31, in <module>
    main()
  File "/opt/calibre/cps/main.py", line 26, in main
    app = create_app()
          ^^^^^^^^^^^^
  File "/opt/calibre/cps/__init__.py", line 175, in create_app
    from .schedule import register_scheduled_tasks, register_startup_tasks
  File "/opt/calibre/cps/schedule.py", line 22, in <module>
    from .services.background_scheduler import BackgroundScheduler, CronTrigger, use_APScheduler
ImportError: cannot import name 'CronTrigger' from 'cps.services.background_scheduler' (/opt/calibre/cps/services/background_scheduler.py)

This is likely due to e178efb

Expected behavior
No crash.

Environment (please complete the following information):

• OS: Alpine Linux
• Python version: python 3.11.1
• Calibre-Web version: 4913f06
• Docker container: None
• Special Hardware: Nope

[OzzieIsaacs]

There is some problem with APScheduler, please try reinstalling it with pip

[jvoisin]

I'm using the one packaged in Alpine Linux, aka 3.9.1-r1.

e178efb added a check around trying to import CronTrigger, and is setting use_APScheduler = False otherwise. Maybe importing CronTrigger and DateTrigger from .services.background_scheduler should be gated behind use_APScheduler?

[faspina]

is there a workaround for this.?

[OzzieIsaacs]

#2653

This is some problem with APScheduler, please try reinstalling it with pip

[dqylyln]

after pip install apscheduler is work