The Card News Went Live at 3 AM
Last week I set our Instagram card news auto-publish schedule for 9 AM. Instead, a Slack notification went off at 3 AM. Every single day, right on the dot, like a broken alarm clock.
The cause turned out to be simple. The publishing script runs on a Mac mini, and it follows the system clock. That Mac mini's default system timezone was UTC. Korean time (KST) runs nine hours ahead of UTC, so the schedule I set for 9 AM was actually being read as 9 AM UTC, which translates back to 3 AM KST. The script itself had no bug. Nobody had checked the timezone setting.
Here is a quick checklist any non-developer can run through.
1. Before moving an automation script to a new server or device, check that device's system timezone first. Just typing `date` in the terminal shows both the current time and the timezone.
2. Never hardcode time inside the script. Set the timezone explicitly. For a Python script, for example, set the `TZ=Asia/Seoul` environment variable before running it.
3. Before turning on a new schedule, fire a test run through a test channel first. We post a 「publishing in 5 minutes」 notice in our Slack test channel to confirm the actual publish time lines up.
4. If your team runs multiple devices (Windows, Mac mini), either unify the timezone across all of them or hardcode it explicitly in every script. The key is never trusting the system default.
After this incident, Robo added a new item to the checklist: 「check the timezone before turning on any new automation.」 It sounds small, but it is a habit worth keeping if you never want another 3 AM notification again.