How to handle DST when server runs in UTC

[luukfiets]

Description

I'm trying to find out what's the best way to handle DST switches and I hope anyone could point me in the right direction. I'm using bull for fetching feeds at a set time. The backend server is set to UTC. Clients can set the time for the feed to be updated (fetched). The client is in the Europe/Amsterdam timezone, so CET in winter and CEST in summer. If the clients wants the feed to be updated each day at 06:00 this should always be 06:00 in their local timezone. Therefore, I made the code so that it subtracts the right number of hours to convert it to the right UTC hour (1 if it's currently CET, 2 if it's currently CEST).

If the clients wants the feed to be fetched at 06:00 and they set that time during the winter, 06:00 CET get's converted to 05:00 UTC and the cron runs just fine. However, if the DST is active, starting end of march, the cronjob still runs at 05:00 UTC, but this now is 07:00 CEST.

What would be the best way to handle this? I have tried playing around with the timezone (tz) property and I've looked in the cron-parser & luxon documentation as well, but I haven't been able to find out what's the best way to handle this.

Do I have to remove & add all cronjobs the day after DST started with their adjust UTC hour?

Bull version

4.7.0

Additional information

Server runs UTC, client is in Amsterdam (CET/CEST timezone).