Build EventBridge Scheduler one-time and recurring schedule configurations.
Last verified: May 2026
Build EventBridge Scheduler one-time and recurring schedules with flexible time windows.
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NameScheduleExpressionFlexibleTimeWindow.ModeTarget.ArnTarget.RoleArnOutput will appear here...Amazon EventBridge Scheduler is a serverless scheduling service that lets you create one-time and recurring schedules to trigger over 270 AWS service API actions. Unlike EventBridge rules with cron expressions, Scheduler supports flexible time windows, automatic retries with dead-letter queues, and timezone-aware scheduling. It can invoke targets like Lambda functions, Step Functions, SQS queues, and any AWS SDK API action. The Scheduler Builder helps you configure schedule expressions (rate, cron, or one-time at()), target configurations, retry policies, and flexible time windows.
Scheduler offers several advantages: timezone support (rules only support UTC), one-time at() schedules, flexible time windows that randomly distribute invocations within a window, built-in retry policies with configurable attempts and DLQ, and the ability to invoke any AWS SDK API as a universal target. Scheduler also supports a much higher scale — millions of schedules per account vs. 300 rules per event bus. Use Scheduler for new scheduled tasks and EventBridge rules when you need event pattern matching.
A flexible time window is a duration (1-15 minutes) during which Scheduler randomly invokes the target. Instead of all schedules firing at exactly 9:00 AM, a 5-minute flexible window distributes invocations randomly between 9:00 and 9:05 AM. This prevents thundering herd effects where thousands of schedules trigger simultaneously, overwhelming downstream services. Flexible windows are optional — set the window to 'off' for precise timing requirements.
Your team has 200 customer-specific cleanup tasks running on a single hour-long Lambda. Each task's failure can corrupt the others. The builder helps generate 200 individual Scheduler schedules: each runs daily at 2 AM in the customer's timezone with a 10-minute flex window, targets a Step Functions state machine, retries 3x with DLQ. Tasks now run in parallel without affecting each other; failures are isolated per-customer; timezone-aware execution means each customer gets cleanup at their actual 2 AM local time, not 2 AM UTC.
The builder constructs EventBridge Scheduler schedule definitions with: schedule expression (rate, cron, or one-time at()), timezone (IANA name), flexible time window (off or 1-15 min), target (any AWS SDK API as Universal Target, or specific service shortcuts like Lambda/SQS/Step Functions/SNS), input payload, retry policy (max attempts, max age), DLQ ARN, and IAM role. Output is generated as aws scheduler create-schedule commands and Terraform aws_scheduler_schedule resources.
EventBridge Scheduler is the right choice in 2026 for ALL new scheduled work. EventBridge rules with cron should only exist for legacy reasons. Scheduler has timezone support, flexible time windows, and 270+ universal targets — rules are limited to 21 target types and UTC only.
Flexible time windows are the killer feature for batch processing. Schedule 1,000 nightly cleanup jobs all at 2:00 AM with a 15-minute flex window, and Scheduler distributes them randomly across 2:00-2:15 — preventing the thundering herd that crashes downstream services.
Always set a DLQ on Scheduler schedules. Without it, failed invocations silently disappear. The retry policy lets you configure max attempts and max age — combine with a DLQ so that genuinely-failed jobs can be inspected later instead of vanishing.
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