AWS EventBridge

* Scheduling Guide

AWS EventBridge Scheduler supports two expression formats: rate(value unit) for simple recurring intervals and cron(fields) for calendar-based schedules. The cron format uses six fields — minute, hour, day-of-month, month, day-of-week, and year — and differs from standard Unix cron in two important ways: the year field is mandatory, and day-of-month and day-of-week are mutually exclusive (one must always be ?). EventBridge evaluates expressions in UTC, so you need to account for timezone offsets when scheduling business-hours jobs. Rate expressions are simpler but cannot target a specific time of day; use the cron format whenever you need the job to run at a predictable wall-clock time.